Cleveland Clinic Journal of Medicine

A 68-year-old man presented with concern about a bluish toe. Several months earlier he had undergone total aortic arch replacement and coronary artery bypass grafting. Since then his renal function had declined and he had been losing weight. 

He had hypercholesterolemia, hypertension, and a 20-pack-year smoking history. Physical examination confirmed that his right great toe was indeed bluish (Figure 1). Peripheral, neck, and abdominal vascular examinations were normal. Laboratory testing revealed:

• Serum creatinine concentration 5.15 mg/dL (reference range 0.61–1.04)
• C-reactive protein level 1.5 mg/dL (0–0.3)
• Eosinophil count 0.58 × 10⁹/L (0–0.50)
• Serum complement level normal
• Urine sediment unremarkable.

Transthoracic echocardiography revealed no evidence of vegetation, and a series of blood cultures were negative. The right toe was biopsied, and study revealed cholesterol clefts (Figure 2), confirming the diagnosis of cholesterol crystal embolism.

He was treated with prednisolone 20 mg/day, and his weight loss and renal function improved.

CHOLESTEROL CRYSTAL EMBOLISM

Cholesterol embolization typically occurs after arteriography, cardiac catheterization, vascular surgery, or anticoagulant use in men over age 55 with atherosclerosis.¹ It presents with renal failure, abdominal pain, systemic symptoms, or, most commonly (in 88% of cases), skin findings.²

“Blue-toe syndrome,” characterized by tissue ischemia, is seen in 65% of patients.² Lesions can appear anywhere on the body, but most commonly on the lower extremities. Most are painful due to ischemia. The condition can progress to necrosis.

Patients may have elevated C-reactive protein, hypocomplementemia (39%), and eosinophilia (80%).^3,4 The diagnosis is confirmed only with histopathologic findings of intravascular cholesterol crystals, seen as cholesterol clefts.

The differential diagnosis includes contrast nephropathy and infectious endocarditis. However, contrast nephropathy begins to recover within several days and is not accompanied by skin lesions. Repeated blood cultures and echocardiography are useful to rule out infectious endocarditis.

Treatment includes managing cardiovascular risk factors and end-organ ischemia and preventing recurrent embolization. Surgical or endovascular treatment has been shown to be effective in decreasing the rate of further embolism.² Corticosteroid therapy is assumed to control the secondary inflammation associated with cholesterol crystal embolism.^1,5

A 68-year-old man presented with concern about a bluish toe. Several months earlier he had undergone total aortic arch replacement and coronary artery bypass grafting. Since then his renal function had declined and he had been losing weight. 

He had hypercholesterolemia, hypertension, and a 20-pack-year smoking history. Physical examination confirmed that his right great toe was indeed bluish (Figure 1). Peripheral, neck, and abdominal vascular examinations were normal. Laboratory testing revealed:

• Serum creatinine concentration 5.15 mg/dL (reference range 0.61–1.04)
• C-reactive protein level 1.5 mg/dL (0–0.3)
• Eosinophil count 0.58 × 10⁹/L (0–0.50)
• Serum complement level normal
• Urine sediment unremarkable.

Transthoracic echocardiography revealed no evidence of vegetation, and a series of blood cultures were negative. The right toe was biopsied, and study revealed cholesterol clefts (Figure 2), confirming the diagnosis of cholesterol crystal embolism.

He was treated with prednisolone 20 mg/day, and his weight loss and renal function improved.

CHOLESTEROL CRYSTAL EMBOLISM

Cholesterol embolization typically occurs after arteriography, cardiac catheterization, vascular surgery, or anticoagulant use in men over age 55 with atherosclerosis.¹ It presents with renal failure, abdominal pain, systemic symptoms, or, most commonly (in 88% of cases), skin findings.²

“Blue-toe syndrome,” characterized by tissue ischemia, is seen in 65% of patients.² Lesions can appear anywhere on the body, but most commonly on the lower extremities. Most are painful due to ischemia. The condition can progress to necrosis.

Patients may have elevated C-reactive protein, hypocomplementemia (39%), and eosinophilia (80%).^3,4 The diagnosis is confirmed only with histopathologic findings of intravascular cholesterol crystals, seen as cholesterol clefts.

The differential diagnosis includes contrast nephropathy and infectious endocarditis. However, contrast nephropathy begins to recover within several days and is not accompanied by skin lesions. Repeated blood cultures and echocardiography are useful to rule out infectious endocarditis.

Treatment includes managing cardiovascular risk factors and end-organ ischemia and preventing recurrent embolization. Surgical or endovascular treatment has been shown to be effective in decreasing the rate of further embolism.² Corticosteroid therapy is assumed to control the secondary inflammation associated with cholesterol crystal embolism.^1,5

A 68-year-old man presented with concern about a bluish toe. Several months earlier he had undergone total aortic arch replacement and coronary artery bypass grafting. Since then his renal function had declined and he had been losing weight. 

He had hypercholesterolemia, hypertension, and a 20-pack-year smoking history. Physical examination confirmed that his right great toe was indeed bluish (Figure 1). Peripheral, neck, and abdominal vascular examinations were normal. Laboratory testing revealed:

• Serum creatinine concentration 5.15 mg/dL (reference range 0.61–1.04)
• C-reactive protein level 1.5 mg/dL (0–0.3)
• Eosinophil count 0.58 × 10⁹/L (0–0.50)
• Serum complement level normal
• Urine sediment unremarkable.

Transthoracic echocardiography revealed no evidence of vegetation, and a series of blood cultures were negative. The right toe was biopsied, and study revealed cholesterol clefts (Figure 2), confirming the diagnosis of cholesterol crystal embolism.

He was treated with prednisolone 20 mg/day, and his weight loss and renal function improved.

CHOLESTEROL CRYSTAL EMBOLISM

Cholesterol embolization typically occurs after arteriography, cardiac catheterization, vascular surgery, or anticoagulant use in men over age 55 with atherosclerosis.¹ It presents with renal failure, abdominal pain, systemic symptoms, or, most commonly (in 88% of cases), skin findings.²

“Blue-toe syndrome,” characterized by tissue ischemia, is seen in 65% of patients.² Lesions can appear anywhere on the body, but most commonly on the lower extremities. Most are painful due to ischemia. The condition can progress to necrosis.

Patients may have elevated C-reactive protein, hypocomplementemia (39%), and eosinophilia (80%).^3,4 The diagnosis is confirmed only with histopathologic findings of intravascular cholesterol crystals, seen as cholesterol clefts.

The differential diagnosis includes contrast nephropathy and infectious endocarditis. However, contrast nephropathy begins to recover within several days and is not accompanied by skin lesions. Repeated blood cultures and echocardiography are useful to rule out infectious endocarditis.

Treatment includes managing cardiovascular risk factors and end-organ ischemia and preventing recurrent embolization. Surgical or endovascular treatment has been shown to be effective in decreasing the rate of further embolism.² Corticosteroid therapy is assumed to control the secondary inflammation associated with cholesterol crystal embolism.^1,5

On the eighth day after giving birth to monochorionic twins, a 33-year-old woman presented with pruritic erythematous papules and plaques that started on the striae of the lower abdomen and spread rapidly to the thighs and upper limbs, sparing the umbilical region (Figure 1). Histologic examination of a specimen of the abdominal plaques showed moderate superficial perivascular lymphohistiocytic infiltrate with eosinophils (Figure 2), leading to the diagnosis of polymorphic eruption of pregnancy. Oral cetirizine 10 mg/day and topical methylprednisolone cream brought complete regression of the lesions within 1 month.

DERMATOSES OF PREGNANCY

Polymorphic eruption of pregnancy—also known as pruritic urticarial papules and plaques of pregnancy¹—is a specific dermatosis of pregnancy characterized by pruritic urticarial papules on abdominal striae that usually first appear during the latter portion of the third trimester or immediately postpartum. It is more frequent in primiparous women and does not represent a risk to the mother or fetus.^2–4

The lesions tend to coalesce into plaques, spreading to the buttocks and proximal thighs. They then become more polymorphic and vesicular, with widespread nonurticated erythema and targetoid and eczematous lesions. Characteristically, the lesions spare the umbilical region. Their location within striae suggests that stretching of abdominal skin may damage the connective tissue, initiating an immune response with subsequent appearance of the eruption.^2,4

The diagnosis is mainly clinical. In some cases, skin biopsy can help to confirm the diagnosis. Histologic features are nonspecific and vary with the stage of disease, showing a superficial to mid-dermal perivascular lymphohistiocytic infiltrate with eosinophils. At earlier stages, biopsy results can show a prominent dermal edema. In later stages, epidermal changes such as spongiosis, hyperkeratosis, and parakeratosis can occur.²

As an aid to diagnosis, Table 1 lists clinical differences between various dermatoses of pregnancy.

On the eighth day after giving birth to monochorionic twins, a 33-year-old woman presented with pruritic erythematous papules and plaques that started on the striae of the lower abdomen and spread rapidly to the thighs and upper limbs, sparing the umbilical region (Figure 1). Histologic examination of a specimen of the abdominal plaques showed moderate superficial perivascular lymphohistiocytic infiltrate with eosinophils (Figure 2), leading to the diagnosis of polymorphic eruption of pregnancy. Oral cetirizine 10 mg/day and topical methylprednisolone cream brought complete regression of the lesions within 1 month.

DERMATOSES OF PREGNANCY

Polymorphic eruption of pregnancy—also known as pruritic urticarial papules and plaques of pregnancy¹—is a specific dermatosis of pregnancy characterized by pruritic urticarial papules on abdominal striae that usually first appear during the latter portion of the third trimester or immediately postpartum. It is more frequent in primiparous women and does not represent a risk to the mother or fetus.^2–4

The lesions tend to coalesce into plaques, spreading to the buttocks and proximal thighs. They then become more polymorphic and vesicular, with widespread nonurticated erythema and targetoid and eczematous lesions. Characteristically, the lesions spare the umbilical region. Their location within striae suggests that stretching of abdominal skin may damage the connective tissue, initiating an immune response with subsequent appearance of the eruption.^2,4

The diagnosis is mainly clinical. In some cases, skin biopsy can help to confirm the diagnosis. Histologic features are nonspecific and vary with the stage of disease, showing a superficial to mid-dermal perivascular lymphohistiocytic infiltrate with eosinophils. At earlier stages, biopsy results can show a prominent dermal edema. In later stages, epidermal changes such as spongiosis, hyperkeratosis, and parakeratosis can occur.²

As an aid to diagnosis, Table 1 lists clinical differences between various dermatoses of pregnancy.

On the eighth day after giving birth to monochorionic twins, a 33-year-old woman presented with pruritic erythematous papules and plaques that started on the striae of the lower abdomen and spread rapidly to the thighs and upper limbs, sparing the umbilical region (Figure 1). Histologic examination of a specimen of the abdominal plaques showed moderate superficial perivascular lymphohistiocytic infiltrate with eosinophils (Figure 2), leading to the diagnosis of polymorphic eruption of pregnancy. Oral cetirizine 10 mg/day and topical methylprednisolone cream brought complete regression of the lesions within 1 month.

DERMATOSES OF PREGNANCY

Polymorphic eruption of pregnancy—also known as pruritic urticarial papules and plaques of pregnancy¹—is a specific dermatosis of pregnancy characterized by pruritic urticarial papules on abdominal striae that usually first appear during the latter portion of the third trimester or immediately postpartum. It is more frequent in primiparous women and does not represent a risk to the mother or fetus.^2–4

The lesions tend to coalesce into plaques, spreading to the buttocks and proximal thighs. They then become more polymorphic and vesicular, with widespread nonurticated erythema and targetoid and eczematous lesions. Characteristically, the lesions spare the umbilical region. Their location within striae suggests that stretching of abdominal skin may damage the connective tissue, initiating an immune response with subsequent appearance of the eruption.^2,4

The diagnosis is mainly clinical. In some cases, skin biopsy can help to confirm the diagnosis. Histologic features are nonspecific and vary with the stage of disease, showing a superficial to mid-dermal perivascular lymphohistiocytic infiltrate with eosinophils. At earlier stages, biopsy results can show a prominent dermal edema. In later stages, epidermal changes such as spongiosis, hyperkeratosis, and parakeratosis can occur.²

As an aid to diagnosis, Table 1 lists clinical differences between various dermatoses of pregnancy.

Autosomal dominant polycystic kidney disease (ADPKD) has significant extrarenal manifestations. Hypertension is a common complication, arises early in the course of the disease, and is implicated in the development of left ventricular hypertrophy. Patients with ADPKD are also at risk of other cardiovascular complications (Table 1).

This article reviews the timely diagnosis of these common ADPKD complications and how to manage them.

ADPKD ACCOUNTS FOR 10% OF END-STAGE RENAL DISEASE

ADPKD is a genetic condition characterized by multiple renal cysts.¹ Progressive enlargement of these cysts leads to a gradual decline in kidney function and eventually end-stage renal disease by the fifth or sixth decade of life.² Worldwide, about 12.5 million people have ADPKD, and it accounts for about 10% of cases of end-stage renal disease.^1,3,4

ADPKD has a variety of clinical presentations, including (in decreasing order of frequency) hypertension, flank pain, abdominal masses, urinary tract infection, renal failure, renal stones, and cerebrovascular accidents.²

Extrarenal complications are common and include hepatic cysts, hypertension, left ventricular hypertrophy, valvular heart disease, intracranial and extracranial aneurysms, pancreatic cysts, and diverticulosis.^1–5

Less-common complications are dissection of the aorta and the internal carotid, vertebral, and iliac arteries^6–10; aneurysm of the coronary, popliteal, and splenic arteries^11–14; atrial myxoma¹⁵; cardiomyopathy¹⁶; pericardial effusion¹⁷; intracranial arterial dolichoectasia¹⁸; arachnoid cysts²; and intraoperative inferior vena cava syndrome (normally in ADPKD patients,  pressure on the inferior vena cava results in compensatory sympathetic overactivity to maintain blood pressure), which occurs due to reduced sympathetic output under the influence of epidural or general anesthesia.¹⁹

Cardiovascular complications, especially cardiac hypertrophy and coronary artery disease, are now the leading cause of death in patients with ADPKD, as renal replacement therapy has improved and made death from end-stage renal disease less common.^20,21

HYPERTENSION IN ADPKD

Hypertension is the most frequent initial presentation of ADPKD, occurring in 50% to 75% of cases and usually preceding the onset of renal failure.^2,22 Hypertension is more common in male ADPKD patients, begins early in the course of the disease, and is diagnosed around the fourth decade of life.²¹

In a study in 2007, de Almeida et al²³ used 24-hour ambulatory blood pressure monitoring early in the course of ADPKD and found significantly higher systolic, diastolic, and mean 24-hour blood pressures in ADPKD patients who had normal in-office blood pressure than in normotensive controls. In addition, nighttime systolic, nighttime diastolic, and nighttime mean blood pressures were significantly higher in the ADPKD group. 

Hypertension is strongly associated with an accelerated decline in renal function to end-stage renal disease, development of left ventricular hypertrophy, and cardiovascular death.^20,24

Although a prospective study²⁵ showed a strong association between renal stones and hypertension in ADPKD, the relation between them is not clear. The incidence of renal stones is higher in hypertensive than in normotensive ADPKD patients, although evidence has to be established whether nephro­lithiasis is a risk factor for hypertension or the other way around.²⁵

Hypertension in ADPKD is multifactorial (Figure 1). The major factors associated with its development are increased activation of the renin-angiotensin-aldosterone system (RAAS); overexpression of endothelin receptor subtype A (ET-A) in cystic kidneys; increased production of endothelin 1 (ET-1); and sodium retention.^26–31

The renin-angiotensin-aldosterone system

Activation of the RAAS plays a major role in the development and maintenance of hypertension in ADPKD. This is thought to be mainly due to progressive enlargement of renal cysts, which causes renal arteriolar attenuation and ischemia secondary to pressure effects, which in turn activates the RAAS.^{26,30,32–34} Two studies in patients with normal renal function found that cyst growth and increasing kidney volume have a strong relationship with the development of hypertension and declining kidney function.^35,36

Ectopic secretion of RAAS components in polycystic kidneys has also been implicated in the development of hypertension, whereby renin, angiotensinogen, angiotensin-converting enzyme (ACE), angiotensin II, and angiotensin II receptors are produced in the epithelium of cysts and dilated tubules in polycystic kidneys.^37–39 Proximal renal cysts and tubules produce ectopic angiotensinogen, which is converted to angiotensin I by renin in distal renal cysts. Angiotensin I is converted to angiotensin II by ACE in distal tubules, which in turn stimulates angiotensin II receptors, causing sodium and water retention in distal tubules.³⁷ This may be responsible for hypertension in the initial stages; however, RAAS hyperactivity due to renal injury may predominate during later stages.³⁷

Increased RAAS activity also increases sympathetic output, which in turn raises catecholamine levels and blood pressure.³⁴ A study showed higher levels of plasma catecholamines in ADPKD hypertensive patients irrespective of renal function than in patients with essential hypertension.⁴⁰

ET-A receptor and ET-1

A few studies have shown that in ADPKD patients, increased density of ET-A receptors and overproduction of ET-1, a potent vasoconstrictor, play a significant role in the development of hypertension and gradual loss of kidney function due to cyst enlargement and interstitial scarring.^28,29 Ong et al²⁹ found that expression of ET-A receptors is increased in smooth muscle cells of renal arteries, glomerular mesangial cells, and cyst epithelia in ADPKD.

Studies in ADPKD patients with preserved renal function have linked high blood pressure to sodium retention and volume expansion.^30,31,41 However, this phenomenon reverses when there is significant renal impairment in ADPKD.

As evidence of this, a study demonstrated significantly more natriuresis in patients with renal failure due to ADPKD than in patients with a similar degree of renal failure due to chronic glomerulonephritis.³¹ Moreover, another study found that the prevalence of hypertension is higher in ADPKD patients than in those with other nephropathies with preserved renal function, but this association reverses with significant decline in kidney function.²²

MANAGING HYPERTENSION IN ADPKD

Early diagnosis of hypertension and effective control of it, even before ADPKD is diagnosed, is crucial to reduce cardiovascular mortality. Aggressive blood pressure control in the prehypertensive phase of ADPKD will also help reduce the incidence of left ventricular hypertrophy and mitral regurgitation and slow the progression of renal failure (Figure 2).

A meta-analysis⁴² revealed hypertension to be present in 20% of ADPKD patients younger than 21, and many of them were undiagnosed. This study also suggests that patients at risk of hypertension (ie, all patients with ADPKD)  should be routinely screened for it.

Ambulatory blood pressure monitoring may play an important role in diagnosing hypertension early in the prehypertensive stage of ADPKD.²³

Target blood pressures: No consensus

Two well-powered double-blind, placebo-controlled trials, known as HALT-PKD Study A and HALT-PKD Study B, tested the effects of 2 different blood pressure targets and of monotherapy with an ACE inhibitor vs combination therapy with an ACE inhibitor plus an angiotensin II receptor blocker (ARB) on renal function, total kidney volume, left ventricular mass index, and urinary albumin excretion in the early (estimated glomerular filtration rate [eGFR] > 60 mL/min) and late (eGFR 25–60 mL/min) stages of ADPKD, respectively.^43,44

HALT-PKD Study A⁴³ found that, in the early stages of ADPKD with preserved renal function, meticulous control of blood pressure (95–110/60–75 mm Hg) was strongly correlated with significant reductions in left ventricular mass index, albuminuria, and rate of total kidney volume growth without remarkable alteration in renal function compared with standard blood pressure control (120–130/70–80 mm Hg). However, no notable differences were observed between the ACE inhibitor and ACE inhibitor-plus-ARB groups.⁴³

Despite the evidence, universal consensus guidelines are lacking, and the available guidelines on hypertension management have different blood pressure goals in patients with chronic kidney disease.

The eighth Joint National Committee guideline of 2014 recommends a blood pressure goal of less than 140/90 mm Hg in patients with diabetic and nondiabetic chronic kidney disease.⁴⁵

The National Institute for Health and Care Excellence 2011 guideline recommends a blood pressure goal of less than 130/80 mm Hg in chronic kidney disease patients.⁴⁶

The European Society of Hypertension and European Society of Cardiology joint 2013 guideline recommends a systolic blood pressure goal of less than 140 mm Hg in diabetic and nondiabetic patients with chronic kidney disease.⁴⁷

The 2016 Kidney Health Australia-Caring for Australians With Renal Impairment guideline for diagnosis and management of ADPKD⁴⁸ recommends a lower blood pressure goal of 96–110/60–75 mm Hg in patients with an eGFR greater than 60 mL/min/1.73 m² who can tolerate it without side effects, which is based on the findings of HALT-PKD Study A.⁴³

Helal et al recommend that blood pressure be controlled to less than 130/80 mm Hg, until there is more evidence for a safe and effective target blood pressure goal in ADPKD patients.⁴⁹

We recommend a target blood pressure less than 110/75 mm Hg in hypertensive ADPKD patients with preserved renal function who can tolerate this level, and less than 130/80 mm Hg in ADPKD patients with stage 3 chronic kidney disease. These targets  can be achieved with ACE inhibitor or ARB monotherapy.^43,44 However, no studies have established the safest lower limit of target blood pressure in ADPKD.

ACE inhibitors, ARBs are mainstays

Mainstays of antihypertensive drug therapy in ADPKD are ACE inhibitors and ARBs.

HALT-PKD Study B⁴⁴ demonstrated that, in the late stages of ADPKD, target blood pressure control (110–130/70–80 mm Hg) can be attained with ACE inhibitor monotherapy or with an ACE inhibitor plus an ARB, but the latter produced no additive benefit.

Patch et al,⁵⁰ in a retrospective cohort study, showed that broadening the spectrum of antihypertensive therapy decreases mortality in ADPKD patients. Evaluating ADPKD patients from the UK General Practice Research Database between 1991 and 2008, they found a trend toward lower mortality rates as the number of antihypertensive drugs prescribed within 1 year increased. They also observed that the prescription of RAAS-blocking agents increased from 7% in 1991 to 46% in 2008.⁵⁰ 

However, a 3-year prospective randomized double-blind study compared the effects of the ACE inhibitor ramipril and the beta-blocker metoprolol in hypertensive ADPKD patients.⁵¹ The results showed that effective blood pressure control could be achieved in both groups with no significant differences in left ventricular mass index, albuminuria, or kidney function.⁵¹

Treatment strategies

Lifestyle modification is the initial approach to the management of hypertension before starting drug therapy. Lifestyle changes include dietary salt restriction to less than 6 g/day, weight reduction, regular exercise, increased fluid intake (up to 3 L/day or to satisfy thirst), smoking cessation, and avoidance of caffeine.^47–49

ACE inhibitors are first-line drugs in hypertensive ADPKD patients.

ARBs can also be considered, but there is no role for dual ACE inhibitor and ARB therapy.^43,48 A study found ACE inhibitors to be more cost-effective and to decrease mortality rates to a greater extent than ARBs.⁵²

Beta-blockers or calcium channel blockers should be considered instead if ACE inhibitors and ARBs are contraindicated,  or as add-on drugs if ACE inhibitors and ARBs fail to reduce blood pressure adequately.^48,49

Diuretics are third-line agents. Thiazides are preferred in ADPKD patients with normal renal function and loop diuretics in those with impaired renal function.⁴⁹

LEFT VENTRICULAR HYPERTROPHY IN ADPKD

Increased left ventricular mass is an indirect indicator of untreated hypertension, and it often goes unnoticed in patients with undiagnosed ADPKD. Left ventricular hypertrophy is associated with arrhythmias and heart failure, which contribute significantly to cardiovascular mortality and adverse renal outcomes.^20,24

A 5-year randomized clinical trial by Cadnapaphornchai et al³⁶ in ADPKD patients between 4 and 21 years of age showed strong correlations between hypertension, left ventricular mass index, and kidney volume and a negative correlation between left ventricular mass index and renal function.

Several factors are thought to contribute to left ventricular hypertrophy in ADPKD (Figure 1).

Hypertension. Two studies of 24-hour ambulatory blood pressure monitoring showed that nocturnal blood pressures decreased less in normotensive and hypertensive ADPKD patients than in normotensive and hypertensive controls.^23,53 This persistent elevation of nocturnal blood pressure may contribute to  the development and progression of left ventricular hypertrophy.

On the other hand, Valero et al⁵⁴ reported that the left ventricular mass index was strongly associated with ambulatory systolic blood pressure rather than elevated nocturnal blood pressure in ADPKD patients compared with healthy controls.

FGF23. High levels of fibroblast growth factor 23 (FGF23) have been shown to be strongly associated with left ventricular hypertrophy in ADPKD. Experimental studies have shown that FGF23 is directly involved in the pathogenesis of left ventricular hypertrophy through stimulation of the calcineurin-nuclear factor of activated T cells pathway.

Faul et al⁵⁵ induced cardiac hypertrophy in mice that were deficient in klotho (a transmembrane protein that increases FGF23 affinity for FGF receptors) by injecting FGF23 intravenously.

Yildiz et al⁵⁶ observed higher levels of FGF23 in hypertensive and normotensive ADPKD patients with normal renal function than in healthy controls. They also found a lower elasticity index in the large and small arteries in normotensive and hypertensive ADPKD patients, which accounts for vascular dysfunction. High FGF23 levels may be responsible for the left ventricular hypertrophy seen in normotensive ADPKD patients with preserved renal function.

Polymorphisms in the ACE gene have been implicated in the development of cardiac hypertrophy in ADPKD.

Wanic-Kossowska et al⁵⁷ studied the association between ACE gene polymorphisms and cardiovascular complications in ADPKD patients. They found a higher prevalence of the homozygous DD genotype among ADPKD patients with end-stage renal disease than in those in the early stages of chronic kidney disease in ADPKD. Also, the DD genotype has been shown to be more strongly associated with left ventricular hypertrophy and left ventricular dysfunction than other (II or ID) genotypes. These findings suggest that the DD genotype carries higher risk for the development of end-stage renal disease, left ventricular hypertrophy, and other cardiovascular complications.

Preventing and halting progression of left ventricular hypertrophy primarily involves effective blood pressure control, especially in the early stages of ADPKD (Figure 2).

A 7-year prospective randomized trial in ADPKD patients with established hypertension and left ventricular hypertrophy proved that aggressive (< 120/80 mm Hg) compared with standard blood pressure control (135–140/85–90 mm Hg) significantly reduces left ventricular mass index. ACE inhibitors were preferred over calcium channel blockers.⁵⁸

HALT-PKD Study A showed that a significant decrease in left ventricular mass index can be achieved by aggressive blood pressure control (95–110/60–75 mm Hg) with an ACE inhibitor alone or in combination with an ARB in the early stages of ADPKD with preserved renal function.⁴³

A 5-year randomized clinical trial in children with borderline hypertension treated with an ACE inhibitor for effective control of blood pressure showed no change in left ventricular mass index or renal function.^36,59

These results support starting ACE inhibitor therapy early in the disease process when blood pressure is still normal or borderline to prevent the progression of left ventricular hypertrophy or worsening kidney function.

Since FGF23 is directly involved in the causation of left ventricular hypertrophy, FGF receptors may be potential therapeutic targets to prevent left ventricular hypertrophy in ADPKD. An FGF receptor blocker was shown to decrease left ventricular hypertrophy in rats with chronic kidney disease without affecting blood pressure.⁵⁵

INTRACRANIAL ANEURYSM IN ADPKD

Intracranial aneurysm is the most dangerous complication of ADPKD. When an aneurysm ruptures, the mortality rate is 4% to 7%, and 50% of survivors are left with residual neurologic deficits.^5,60,61

In various studies, the prevalence of intracranial aneurysm in ADPKD ranged from 4% to 41.2%, compared with 1% in the general population.^5,62,63 On follow-up ranging from 18 months to about 10 years, the incidence of new intracranial aneurysm was 2.6% to 13.3% in patients with previously normal findings on magnetic resonance angiography and 25% in patients with a history of intracranial aneurysm.^62,64,65

The most common sites are the middle cerebral artery (45%), internal carotid artery (40.5%), and anterior communicating artery (35.1%).⁶⁶ (The numbers add up to more than 100% because some patients have aneurysms in more than 1 site.) The mean size of a ruptured aneurysm was 6 mm per a recent systematic review.⁶⁶ Intracranial aneurysms 6 mm or larger are at highest risk of rupture.⁶⁶

SCREENING FOR INTRACRANIAL ANEURYSM

Timely screening and intervention for intracranial aneurysm is crucial to prevent death from intracranial hemorrhage.

Currently, there are no standard guidelines for screening and follow-up of intracranial aneurysm in ADPKD patients. However, some recommendations are available from the ADPKD Kidney Disease Improving Global Outcomes Controversies Conference³ and Kidney Health Australia—Caring for Australasians With Renal Impairment ADPKD guidelines⁶⁷ (Figure 3).

Imaging tests

Magnetic resonance angiography (MRA) with gadolinium enhancement and computed tomographic angiography (CTA) are recommended for screening in ADPKD patients with normal renal function,⁶⁷ but time-of-flight MRA without gadolinium is the imaging test of choice because it is noninvasive and poses no risk of nephrotoxicity or contrast allergy.^3,68 Further, gadolinium should be avoided in patients whose eGFR is 30 mL/min/1.73 m² or less because of risk of nephrogenic systemic sclerosis and fibrosis.^67,68

The sensitivity of time-of-flight MRA screening for intracranial aneurysm varies depending on the size of aneurysm; 67% for those less than 3 mm, 79% for those 3 to 5 mm, and 95% for those larger than 5 mm.⁶⁹ The sensitivity of CTA screening is 95% for aneurysms larger than 7 mm and 53% for those measuring 2 mm.^70,71 The specificity of CTA screening was reported to be 98.9% overall.⁷¹

When to screen

Screening for intracranial aneurysm is recommended at the time of ADPKD diagnosis for all high-risk patients, ie, those who have a family history of intracranial hemorrhage or aneurysm in an affected first-degree relative.⁶⁷ It is also recommended for ADPKD patients with a history of sudden-onset severe headache or neurologic symptoms.⁶⁷ A third group for whom screening is recommended is ADPKD patients who have no family history of intracranial aneurysm or hemorrhage but who are at risk of poor outcome if an intracranial aneurysm ruptures (eg, those undergoing major elective surgery, with uncontrolled blood pressure, on anticoagulation, with a history of or current smoking, and airline pilots).⁶⁷

Patients found to have an intracranial aneurysm on screening should be referred to a neurosurgeon and should undergo repeat MRA or CTA imaging every 6 to 24 months.³ High-risk ADPKD patients with normal findings on initial screening should have repeat MRA or CTA screening in 5 to 10 years unless they suffer from sudden-onset severe headache or neurologic symptoms.^65,67

Both smoking and high blood pressure increase the risk of formation and growth of intracranial aneurysm. Hence, meticulous control of blood pressure and smoking cessation are recommended in ADPKD patients.^3,67

CARDIAC VALVULAR ABNORMALITIES IN ADPKD

Of the valvular abnormalities that complicate ADPKD, the more common ones are mitral valve prolapse and mitral and aortic regurgitation. The less common ones are tricuspid valve prolapse and tricuspid regurgitation.^72–74

The pathophysiology underlying these valvular abnormalities is unclear. However, defective collagen synthesis and myxomatous degeneration have been demonstrated in histopathologic examination of affected valvular tissue.⁷⁵ Also, ACE gene polymorphism, especially the DD genotype, has been shown to be associated with cardiac valvular calcifications and valvular insufficiency.⁵⁷

Lumiaho et al⁷² found a higher prevalence of mitral valve prolapse, mitral regurgitation, and left ventricular hypertrophy in patients with ADPKD type 1 (due to abnormalities in PDK1) than in unaffected family members and healthy controls. The investigators speculated that mitral regurgitation is caused by the high blood pressure observed in ADPKD type 1 patients, since hypertension causes left ventricular hypertrophy and left ventricular dilatation. The severity of renal failure was related to mitral regurgitation but not mitral valve prolapse.

Similarly, Gabow et al²⁴ showed that there is no significant relationship between mitral valve prolapse and progression of renal disease in ADPKD.

Interestingly, Fick et al²⁰ found that mitral valve prolapse has no significant effect on cardiovascular mortality.

Atherosclerosis sets in early in ADPKD, resulting in coronary artery disease and adverse cardiovascular outcomes.

Coronary flow velocity reserve is the ability of coronary arteries to dilate in response to myocardial oxygen demand. Atherosclerosis decreases this reserve in ADPKD patients, as shown in several studies.

Turkmen et al, in a series of studies,^76–78 found that ADPKD patients had significantly less coronary flow velocity reserve, thicker carotid intima media (a surrogate marker of atherosclerosis), and greater insulin resistance than healthy controls. These findings imply that atherosclerosis begins very early in the course of ADPKD and has remarkable effects on cardiovascular morbidity and mortality.⁷⁶

Aneurysm. Although the risk of extracranial aneurysm is higher with ADPKD, coronary artery aneurysm is uncommon. The pathogenesis of coronary aneurysm has been linked to abnormal expression of the proteins polycystin 1 and polycystin 2 in vascular smooth muscle.^11,79 The PKD1 and PKD2 genes encode polycystin 1 and 2, respectively, in ADPKD. These polycystins are also expressed in the liver, kidneys, and myocardium and are involved in the regulation of intracellular calcium, stretch-activated ion channels, and vascular smooth muscle cell proliferation and apoptosis.^11,16 Abnormally expressed polycystin in ADPKD therefore has an impact on arterial wall integrity, resulting in focal medial defects in the vasculature that eventually develop into micro- and macroaneurysms.¹¹

Hadimeri et al⁷⁹ found a higher prevalence of coronary aneurysm and ectasia in ADPKD patients than in controls. Most coronary aneurysms are smaller than 1 cm; however, a coronary aneurysm measuring 4 cm in diameter was found at autopsy of an ADPKD patient.¹¹

Spontaneous coronary artery dissection is very rare in the general population, but Bobrie et al reported a case of it in an ADPKD patient.⁹

ATRIAL MYXOMA, CARDIOMYOPATHY, AND PERICARDIAL EFFUSION IN ADPKD

Atrial myxoma in ADPKD patients has been described in 2 case reports.^15,80 However, the association of atrial myxoma with ADPKD is poorly understood and may be a coincidental finding.

Cardiomyopathy in ADPKD has been linked to abnormalities in the intracellular calcium pathway, although a clear picture of its involvement has yet to be established.

Paavola et al¹⁶ described the pathophysiology of ADPKD-associated cardiomyopathy in PKD2 mutant zebrafish lacking polycystin 2. These mutants showed decreased cardiac output and had atrioventricular blocks. The findings  were attributed to abnormal intracellular calcium cycling. These findings correlated well with the frequent finding of idiopathic dilated cardiomyopathy in ADPKD patients, especially with PKD2 mutations.¹⁶ Also, 2 cases of dilated cardiomyopathy in ADPKD have been reported and thought to be related to PKD2 mutations.^81,82

Pericardial effusion. Even though the exact pathophysiology of pericardial effusion in ADPKD is unknown, it has been theorized to be related to defects in connective tissue and extracellular matrix due to PKD1 and PKD2 mutations. These abnormalities increase the compliance and impair the recoil capacity of connective tissue, which results in unusual distention of the parietal pericardium. This abnormal distention of the parietal pericardium together with increased extracellular volume may lead to pericardial effusion.¹⁷

Qian et al¹⁷ found a higher prevalence of pericardial effusion in ADPKD patients. It was generally asymptomatic, and the cause was attributed to these connective tissue and extracellular matrix abnormalities.

EMERGING THERAPIES AND TESTS

Recent trials have investigated the effects of vasopressin receptor antagonists, specifically V2 receptor blockers in ADPKD and its complications.

Tolvaptan has been shown to slow the rate of increase in cyst size and total kidney volume.^83,84 Also, a correlation between kidney size and diastolic blood pressure has been observed in ADPKD patients.⁸⁵ Reducing cyst volume may reduce pressure effects and decrease renal ischemia, which in turn may reduce RAAS activation; however, the evidence to support this hypothesis is poor. A major clinical trial of tolvaptan in ADPKD patients showed no effect on blood pressure control, but the drug slowed the rate of increase in total kidney volume and fall in eGFR.⁸³

Endothelin receptor antagonists are also in the preliminary stage of development for use in ADPKD. The effects of acute blockade of the renal endothelial system with bosentan were  investigated in animal models by Hocher et al.²⁸ This study showed a greater reduction in mean arterial pressure after bosentan administration, resulting in significantly decreased GFR and renal blood flow. Nonetheless, the mean arterial pressure-lowering effect of bosentan was more marked than the reductions in GFR and renal blood flow.

Raina et al,⁸⁶ in a pilot cross-sectional analysis, showed that urinary excretion of ET-1 is increased in ADPKD patients, and may serve as a surrogate marker for ET-1 in renal tissue and a noninvasive marker of early kidney injury.

Autosomal dominant polycystic kidney disease (ADPKD) has significant extrarenal manifestations. Hypertension is a common complication, arises early in the course of the disease, and is implicated in the development of left ventricular hypertrophy. Patients with ADPKD are also at risk of other cardiovascular complications (Table 1).

This article reviews the timely diagnosis of these common ADPKD complications and how to manage them.

ADPKD ACCOUNTS FOR 10% OF END-STAGE RENAL DISEASE

ADPKD is a genetic condition characterized by multiple renal cysts.¹ Progressive enlargement of these cysts leads to a gradual decline in kidney function and eventually end-stage renal disease by the fifth or sixth decade of life.² Worldwide, about 12.5 million people have ADPKD, and it accounts for about 10% of cases of end-stage renal disease.^1,3,4

ADPKD has a variety of clinical presentations, including (in decreasing order of frequency) hypertension, flank pain, abdominal masses, urinary tract infection, renal failure, renal stones, and cerebrovascular accidents.²

Extrarenal complications are common and include hepatic cysts, hypertension, left ventricular hypertrophy, valvular heart disease, intracranial and extracranial aneurysms, pancreatic cysts, and diverticulosis.^1–5

Less-common complications are dissection of the aorta and the internal carotid, vertebral, and iliac arteries^6–10; aneurysm of the coronary, popliteal, and splenic arteries^11–14; atrial myxoma¹⁵; cardiomyopathy¹⁶; pericardial effusion¹⁷; intracranial arterial dolichoectasia¹⁸; arachnoid cysts²; and intraoperative inferior vena cava syndrome (normally in ADPKD patients,  pressure on the inferior vena cava results in compensatory sympathetic overactivity to maintain blood pressure), which occurs due to reduced sympathetic output under the influence of epidural or general anesthesia.¹⁹

Cardiovascular complications, especially cardiac hypertrophy and coronary artery disease, are now the leading cause of death in patients with ADPKD, as renal replacement therapy has improved and made death from end-stage renal disease less common.^20,21

HYPERTENSION IN ADPKD

Hypertension is the most frequent initial presentation of ADPKD, occurring in 50% to 75% of cases and usually preceding the onset of renal failure.^2,22 Hypertension is more common in male ADPKD patients, begins early in the course of the disease, and is diagnosed around the fourth decade of life.²¹

In a study in 2007, de Almeida et al²³ used 24-hour ambulatory blood pressure monitoring early in the course of ADPKD and found significantly higher systolic, diastolic, and mean 24-hour blood pressures in ADPKD patients who had normal in-office blood pressure than in normotensive controls. In addition, nighttime systolic, nighttime diastolic, and nighttime mean blood pressures were significantly higher in the ADPKD group. 

Hypertension is strongly associated with an accelerated decline in renal function to end-stage renal disease, development of left ventricular hypertrophy, and cardiovascular death.^20,24

Although a prospective study²⁵ showed a strong association between renal stones and hypertension in ADPKD, the relation between them is not clear. The incidence of renal stones is higher in hypertensive than in normotensive ADPKD patients, although evidence has to be established whether nephro­lithiasis is a risk factor for hypertension or the other way around.²⁵

Hypertension in ADPKD is multifactorial (Figure 1). The major factors associated with its development are increased activation of the renin-angiotensin-aldosterone system (RAAS); overexpression of endothelin receptor subtype A (ET-A) in cystic kidneys; increased production of endothelin 1 (ET-1); and sodium retention.^26–31

The renin-angiotensin-aldosterone system

Activation of the RAAS plays a major role in the development and maintenance of hypertension in ADPKD. This is thought to be mainly due to progressive enlargement of renal cysts, which causes renal arteriolar attenuation and ischemia secondary to pressure effects, which in turn activates the RAAS.^{26,30,32–34} Two studies in patients with normal renal function found that cyst growth and increasing kidney volume have a strong relationship with the development of hypertension and declining kidney function.^35,36

Ectopic secretion of RAAS components in polycystic kidneys has also been implicated in the development of hypertension, whereby renin, angiotensinogen, angiotensin-converting enzyme (ACE), angiotensin II, and angiotensin II receptors are produced in the epithelium of cysts and dilated tubules in polycystic kidneys.^37–39 Proximal renal cysts and tubules produce ectopic angiotensinogen, which is converted to angiotensin I by renin in distal renal cysts. Angiotensin I is converted to angiotensin II by ACE in distal tubules, which in turn stimulates angiotensin II receptors, causing sodium and water retention in distal tubules.³⁷ This may be responsible for hypertension in the initial stages; however, RAAS hyperactivity due to renal injury may predominate during later stages.³⁷

Increased RAAS activity also increases sympathetic output, which in turn raises catecholamine levels and blood pressure.³⁴ A study showed higher levels of plasma catecholamines in ADPKD hypertensive patients irrespective of renal function than in patients with essential hypertension.⁴⁰

ET-A receptor and ET-1

A few studies have shown that in ADPKD patients, increased density of ET-A receptors and overproduction of ET-1, a potent vasoconstrictor, play a significant role in the development of hypertension and gradual loss of kidney function due to cyst enlargement and interstitial scarring.^28,29 Ong et al²⁹ found that expression of ET-A receptors is increased in smooth muscle cells of renal arteries, glomerular mesangial cells, and cyst epithelia in ADPKD.

Studies in ADPKD patients with preserved renal function have linked high blood pressure to sodium retention and volume expansion.^30,31,41 However, this phenomenon reverses when there is significant renal impairment in ADPKD.

As evidence of this, a study demonstrated significantly more natriuresis in patients with renal failure due to ADPKD than in patients with a similar degree of renal failure due to chronic glomerulonephritis.³¹ Moreover, another study found that the prevalence of hypertension is higher in ADPKD patients than in those with other nephropathies with preserved renal function, but this association reverses with significant decline in kidney function.²²

MANAGING HYPERTENSION IN ADPKD

Early diagnosis of hypertension and effective control of it, even before ADPKD is diagnosed, is crucial to reduce cardiovascular mortality. Aggressive blood pressure control in the prehypertensive phase of ADPKD will also help reduce the incidence of left ventricular hypertrophy and mitral regurgitation and slow the progression of renal failure (Figure 2).

A meta-analysis⁴² revealed hypertension to be present in 20% of ADPKD patients younger than 21, and many of them were undiagnosed. This study also suggests that patients at risk of hypertension (ie, all patients with ADPKD)  should be routinely screened for it.

Ambulatory blood pressure monitoring may play an important role in diagnosing hypertension early in the prehypertensive stage of ADPKD.²³

Target blood pressures: No consensus

Two well-powered double-blind, placebo-controlled trials, known as HALT-PKD Study A and HALT-PKD Study B, tested the effects of 2 different blood pressure targets and of monotherapy with an ACE inhibitor vs combination therapy with an ACE inhibitor plus an angiotensin II receptor blocker (ARB) on renal function, total kidney volume, left ventricular mass index, and urinary albumin excretion in the early (estimated glomerular filtration rate [eGFR] > 60 mL/min) and late (eGFR 25–60 mL/min) stages of ADPKD, respectively.^43,44

HALT-PKD Study A⁴³ found that, in the early stages of ADPKD with preserved renal function, meticulous control of blood pressure (95–110/60–75 mm Hg) was strongly correlated with significant reductions in left ventricular mass index, albuminuria, and rate of total kidney volume growth without remarkable alteration in renal function compared with standard blood pressure control (120–130/70–80 mm Hg). However, no notable differences were observed between the ACE inhibitor and ACE inhibitor-plus-ARB groups.⁴³

Despite the evidence, universal consensus guidelines are lacking, and the available guidelines on hypertension management have different blood pressure goals in patients with chronic kidney disease.

The eighth Joint National Committee guideline of 2014 recommends a blood pressure goal of less than 140/90 mm Hg in patients with diabetic and nondiabetic chronic kidney disease.⁴⁵

The National Institute for Health and Care Excellence 2011 guideline recommends a blood pressure goal of less than 130/80 mm Hg in chronic kidney disease patients.⁴⁶

The European Society of Hypertension and European Society of Cardiology joint 2013 guideline recommends a systolic blood pressure goal of less than 140 mm Hg in diabetic and nondiabetic patients with chronic kidney disease.⁴⁷

The 2016 Kidney Health Australia-Caring for Australians With Renal Impairment guideline for diagnosis and management of ADPKD⁴⁸ recommends a lower blood pressure goal of 96–110/60–75 mm Hg in patients with an eGFR greater than 60 mL/min/1.73 m² who can tolerate it without side effects, which is based on the findings of HALT-PKD Study A.⁴³

Helal et al recommend that blood pressure be controlled to less than 130/80 mm Hg, until there is more evidence for a safe and effective target blood pressure goal in ADPKD patients.⁴⁹

We recommend a target blood pressure less than 110/75 mm Hg in hypertensive ADPKD patients with preserved renal function who can tolerate this level, and less than 130/80 mm Hg in ADPKD patients with stage 3 chronic kidney disease. These targets  can be achieved with ACE inhibitor or ARB monotherapy.^43,44 However, no studies have established the safest lower limit of target blood pressure in ADPKD.

ACE inhibitors, ARBs are mainstays

Mainstays of antihypertensive drug therapy in ADPKD are ACE inhibitors and ARBs.

HALT-PKD Study B⁴⁴ demonstrated that, in the late stages of ADPKD, target blood pressure control (110–130/70–80 mm Hg) can be attained with ACE inhibitor monotherapy or with an ACE inhibitor plus an ARB, but the latter produced no additive benefit.

Patch et al,⁵⁰ in a retrospective cohort study, showed that broadening the spectrum of antihypertensive therapy decreases mortality in ADPKD patients. Evaluating ADPKD patients from the UK General Practice Research Database between 1991 and 2008, they found a trend toward lower mortality rates as the number of antihypertensive drugs prescribed within 1 year increased. They also observed that the prescription of RAAS-blocking agents increased from 7% in 1991 to 46% in 2008.⁵⁰ 

However, a 3-year prospective randomized double-blind study compared the effects of the ACE inhibitor ramipril and the beta-blocker metoprolol in hypertensive ADPKD patients.⁵¹ The results showed that effective blood pressure control could be achieved in both groups with no significant differences in left ventricular mass index, albuminuria, or kidney function.⁵¹

Treatment strategies

Lifestyle modification is the initial approach to the management of hypertension before starting drug therapy. Lifestyle changes include dietary salt restriction to less than 6 g/day, weight reduction, regular exercise, increased fluid intake (up to 3 L/day or to satisfy thirst), smoking cessation, and avoidance of caffeine.^47–49

ACE inhibitors are first-line drugs in hypertensive ADPKD patients.

ARBs can also be considered, but there is no role for dual ACE inhibitor and ARB therapy.^43,48 A study found ACE inhibitors to be more cost-effective and to decrease mortality rates to a greater extent than ARBs.⁵²

Beta-blockers or calcium channel blockers should be considered instead if ACE inhibitors and ARBs are contraindicated,  or as add-on drugs if ACE inhibitors and ARBs fail to reduce blood pressure adequately.^48,49

Diuretics are third-line agents. Thiazides are preferred in ADPKD patients with normal renal function and loop diuretics in those with impaired renal function.⁴⁹

LEFT VENTRICULAR HYPERTROPHY IN ADPKD

Increased left ventricular mass is an indirect indicator of untreated hypertension, and it often goes unnoticed in patients with undiagnosed ADPKD. Left ventricular hypertrophy is associated with arrhythmias and heart failure, which contribute significantly to cardiovascular mortality and adverse renal outcomes.^20,24

A 5-year randomized clinical trial by Cadnapaphornchai et al³⁶ in ADPKD patients between 4 and 21 years of age showed strong correlations between hypertension, left ventricular mass index, and kidney volume and a negative correlation between left ventricular mass index and renal function.

Several factors are thought to contribute to left ventricular hypertrophy in ADPKD (Figure 1).

Hypertension. Two studies of 24-hour ambulatory blood pressure monitoring showed that nocturnal blood pressures decreased less in normotensive and hypertensive ADPKD patients than in normotensive and hypertensive controls.^23,53 This persistent elevation of nocturnal blood pressure may contribute to  the development and progression of left ventricular hypertrophy.

On the other hand, Valero et al⁵⁴ reported that the left ventricular mass index was strongly associated with ambulatory systolic blood pressure rather than elevated nocturnal blood pressure in ADPKD patients compared with healthy controls.

FGF23. High levels of fibroblast growth factor 23 (FGF23) have been shown to be strongly associated with left ventricular hypertrophy in ADPKD. Experimental studies have shown that FGF23 is directly involved in the pathogenesis of left ventricular hypertrophy through stimulation of the calcineurin-nuclear factor of activated T cells pathway.

Faul et al⁵⁵ induced cardiac hypertrophy in mice that were deficient in klotho (a transmembrane protein that increases FGF23 affinity for FGF receptors) by injecting FGF23 intravenously.

Yildiz et al⁵⁶ observed higher levels of FGF23 in hypertensive and normotensive ADPKD patients with normal renal function than in healthy controls. They also found a lower elasticity index in the large and small arteries in normotensive and hypertensive ADPKD patients, which accounts for vascular dysfunction. High FGF23 levels may be responsible for the left ventricular hypertrophy seen in normotensive ADPKD patients with preserved renal function.

Polymorphisms in the ACE gene have been implicated in the development of cardiac hypertrophy in ADPKD.

Wanic-Kossowska et al⁵⁷ studied the association between ACE gene polymorphisms and cardiovascular complications in ADPKD patients. They found a higher prevalence of the homozygous DD genotype among ADPKD patients with end-stage renal disease than in those in the early stages of chronic kidney disease in ADPKD. Also, the DD genotype has been shown to be more strongly associated with left ventricular hypertrophy and left ventricular dysfunction than other (II or ID) genotypes. These findings suggest that the DD genotype carries higher risk for the development of end-stage renal disease, left ventricular hypertrophy, and other cardiovascular complications.

Preventing and halting progression of left ventricular hypertrophy primarily involves effective blood pressure control, especially in the early stages of ADPKD (Figure 2).

A 7-year prospective randomized trial in ADPKD patients with established hypertension and left ventricular hypertrophy proved that aggressive (< 120/80 mm Hg) compared with standard blood pressure control (135–140/85–90 mm Hg) significantly reduces left ventricular mass index. ACE inhibitors were preferred over calcium channel blockers.⁵⁸

HALT-PKD Study A showed that a significant decrease in left ventricular mass index can be achieved by aggressive blood pressure control (95–110/60–75 mm Hg) with an ACE inhibitor alone or in combination with an ARB in the early stages of ADPKD with preserved renal function.⁴³

A 5-year randomized clinical trial in children with borderline hypertension treated with an ACE inhibitor for effective control of blood pressure showed no change in left ventricular mass index or renal function.^36,59

These results support starting ACE inhibitor therapy early in the disease process when blood pressure is still normal or borderline to prevent the progression of left ventricular hypertrophy or worsening kidney function.

Since FGF23 is directly involved in the causation of left ventricular hypertrophy, FGF receptors may be potential therapeutic targets to prevent left ventricular hypertrophy in ADPKD. An FGF receptor blocker was shown to decrease left ventricular hypertrophy in rats with chronic kidney disease without affecting blood pressure.⁵⁵

INTRACRANIAL ANEURYSM IN ADPKD

Intracranial aneurysm is the most dangerous complication of ADPKD. When an aneurysm ruptures, the mortality rate is 4% to 7%, and 50% of survivors are left with residual neurologic deficits.^5,60,61

In various studies, the prevalence of intracranial aneurysm in ADPKD ranged from 4% to 41.2%, compared with 1% in the general population.^5,62,63 On follow-up ranging from 18 months to about 10 years, the incidence of new intracranial aneurysm was 2.6% to 13.3% in patients with previously normal findings on magnetic resonance angiography and 25% in patients with a history of intracranial aneurysm.^62,64,65

The most common sites are the middle cerebral artery (45%), internal carotid artery (40.5%), and anterior communicating artery (35.1%).⁶⁶ (The numbers add up to more than 100% because some patients have aneurysms in more than 1 site.) The mean size of a ruptured aneurysm was 6 mm per a recent systematic review.⁶⁶ Intracranial aneurysms 6 mm or larger are at highest risk of rupture.⁶⁶

SCREENING FOR INTRACRANIAL ANEURYSM

Timely screening and intervention for intracranial aneurysm is crucial to prevent death from intracranial hemorrhage.

Currently, there are no standard guidelines for screening and follow-up of intracranial aneurysm in ADPKD patients. However, some recommendations are available from the ADPKD Kidney Disease Improving Global Outcomes Controversies Conference³ and Kidney Health Australia—Caring for Australasians With Renal Impairment ADPKD guidelines⁶⁷ (Figure 3).

Imaging tests

Magnetic resonance angiography (MRA) with gadolinium enhancement and computed tomographic angiography (CTA) are recommended for screening in ADPKD patients with normal renal function,⁶⁷ but time-of-flight MRA without gadolinium is the imaging test of choice because it is noninvasive and poses no risk of nephrotoxicity or contrast allergy.^3,68 Further, gadolinium should be avoided in patients whose eGFR is 30 mL/min/1.73 m² or less because of risk of nephrogenic systemic sclerosis and fibrosis.^67,68

The sensitivity of time-of-flight MRA screening for intracranial aneurysm varies depending on the size of aneurysm; 67% for those less than 3 mm, 79% for those 3 to 5 mm, and 95% for those larger than 5 mm.⁶⁹ The sensitivity of CTA screening is 95% for aneurysms larger than 7 mm and 53% for those measuring 2 mm.^70,71 The specificity of CTA screening was reported to be 98.9% overall.⁷¹

When to screen

Screening for intracranial aneurysm is recommended at the time of ADPKD diagnosis for all high-risk patients, ie, those who have a family history of intracranial hemorrhage or aneurysm in an affected first-degree relative.⁶⁷ It is also recommended for ADPKD patients with a history of sudden-onset severe headache or neurologic symptoms.⁶⁷ A third group for whom screening is recommended is ADPKD patients who have no family history of intracranial aneurysm or hemorrhage but who are at risk of poor outcome if an intracranial aneurysm ruptures (eg, those undergoing major elective surgery, with uncontrolled blood pressure, on anticoagulation, with a history of or current smoking, and airline pilots).⁶⁷

Patients found to have an intracranial aneurysm on screening should be referred to a neurosurgeon and should undergo repeat MRA or CTA imaging every 6 to 24 months.³ High-risk ADPKD patients with normal findings on initial screening should have repeat MRA or CTA screening in 5 to 10 years unless they suffer from sudden-onset severe headache or neurologic symptoms.^65,67

Both smoking and high blood pressure increase the risk of formation and growth of intracranial aneurysm. Hence, meticulous control of blood pressure and smoking cessation are recommended in ADPKD patients.^3,67

CARDIAC VALVULAR ABNORMALITIES IN ADPKD

Of the valvular abnormalities that complicate ADPKD, the more common ones are mitral valve prolapse and mitral and aortic regurgitation. The less common ones are tricuspid valve prolapse and tricuspid regurgitation.^72–74

The pathophysiology underlying these valvular abnormalities is unclear. However, defective collagen synthesis and myxomatous degeneration have been demonstrated in histopathologic examination of affected valvular tissue.⁷⁵ Also, ACE gene polymorphism, especially the DD genotype, has been shown to be associated with cardiac valvular calcifications and valvular insufficiency.⁵⁷

Lumiaho et al⁷² found a higher prevalence of mitral valve prolapse, mitral regurgitation, and left ventricular hypertrophy in patients with ADPKD type 1 (due to abnormalities in PDK1) than in unaffected family members and healthy controls. The investigators speculated that mitral regurgitation is caused by the high blood pressure observed in ADPKD type 1 patients, since hypertension causes left ventricular hypertrophy and left ventricular dilatation. The severity of renal failure was related to mitral regurgitation but not mitral valve prolapse.

Similarly, Gabow et al²⁴ showed that there is no significant relationship between mitral valve prolapse and progression of renal disease in ADPKD.

Interestingly, Fick et al²⁰ found that mitral valve prolapse has no significant effect on cardiovascular mortality.

Atherosclerosis sets in early in ADPKD, resulting in coronary artery disease and adverse cardiovascular outcomes.

Coronary flow velocity reserve is the ability of coronary arteries to dilate in response to myocardial oxygen demand. Atherosclerosis decreases this reserve in ADPKD patients, as shown in several studies.

Turkmen et al, in a series of studies,^76–78 found that ADPKD patients had significantly less coronary flow velocity reserve, thicker carotid intima media (a surrogate marker of atherosclerosis), and greater insulin resistance than healthy controls. These findings imply that atherosclerosis begins very early in the course of ADPKD and has remarkable effects on cardiovascular morbidity and mortality.⁷⁶

Aneurysm. Although the risk of extracranial aneurysm is higher with ADPKD, coronary artery aneurysm is uncommon. The pathogenesis of coronary aneurysm has been linked to abnormal expression of the proteins polycystin 1 and polycystin 2 in vascular smooth muscle.^11,79 The PKD1 and PKD2 genes encode polycystin 1 and 2, respectively, in ADPKD. These polycystins are also expressed in the liver, kidneys, and myocardium and are involved in the regulation of intracellular calcium, stretch-activated ion channels, and vascular smooth muscle cell proliferation and apoptosis.^11,16 Abnormally expressed polycystin in ADPKD therefore has an impact on arterial wall integrity, resulting in focal medial defects in the vasculature that eventually develop into micro- and macroaneurysms.¹¹

Hadimeri et al⁷⁹ found a higher prevalence of coronary aneurysm and ectasia in ADPKD patients than in controls. Most coronary aneurysms are smaller than 1 cm; however, a coronary aneurysm measuring 4 cm in diameter was found at autopsy of an ADPKD patient.¹¹

Spontaneous coronary artery dissection is very rare in the general population, but Bobrie et al reported a case of it in an ADPKD patient.⁹

ATRIAL MYXOMA, CARDIOMYOPATHY, AND PERICARDIAL EFFUSION IN ADPKD

Atrial myxoma in ADPKD patients has been described in 2 case reports.^15,80 However, the association of atrial myxoma with ADPKD is poorly understood and may be a coincidental finding.

Cardiomyopathy in ADPKD has been linked to abnormalities in the intracellular calcium pathway, although a clear picture of its involvement has yet to be established.

Paavola et al¹⁶ described the pathophysiology of ADPKD-associated cardiomyopathy in PKD2 mutant zebrafish lacking polycystin 2. These mutants showed decreased cardiac output and had atrioventricular blocks. The findings  were attributed to abnormal intracellular calcium cycling. These findings correlated well with the frequent finding of idiopathic dilated cardiomyopathy in ADPKD patients, especially with PKD2 mutations.¹⁶ Also, 2 cases of dilated cardiomyopathy in ADPKD have been reported and thought to be related to PKD2 mutations.^81,82

Pericardial effusion. Even though the exact pathophysiology of pericardial effusion in ADPKD is unknown, it has been theorized to be related to defects in connective tissue and extracellular matrix due to PKD1 and PKD2 mutations. These abnormalities increase the compliance and impair the recoil capacity of connective tissue, which results in unusual distention of the parietal pericardium. This abnormal distention of the parietal pericardium together with increased extracellular volume may lead to pericardial effusion.¹⁷

Qian et al¹⁷ found a higher prevalence of pericardial effusion in ADPKD patients. It was generally asymptomatic, and the cause was attributed to these connective tissue and extracellular matrix abnormalities.

EMERGING THERAPIES AND TESTS

Recent trials have investigated the effects of vasopressin receptor antagonists, specifically V2 receptor blockers in ADPKD and its complications.

Tolvaptan has been shown to slow the rate of increase in cyst size and total kidney volume.^83,84 Also, a correlation between kidney size and diastolic blood pressure has been observed in ADPKD patients.⁸⁵ Reducing cyst volume may reduce pressure effects and decrease renal ischemia, which in turn may reduce RAAS activation; however, the evidence to support this hypothesis is poor. A major clinical trial of tolvaptan in ADPKD patients showed no effect on blood pressure control, but the drug slowed the rate of increase in total kidney volume and fall in eGFR.⁸³

Endothelin receptor antagonists are also in the preliminary stage of development for use in ADPKD. The effects of acute blockade of the renal endothelial system with bosentan were  investigated in animal models by Hocher et al.²⁸ This study showed a greater reduction in mean arterial pressure after bosentan administration, resulting in significantly decreased GFR and renal blood flow. Nonetheless, the mean arterial pressure-lowering effect of bosentan was more marked than the reductions in GFR and renal blood flow.

Raina et al,⁸⁶ in a pilot cross-sectional analysis, showed that urinary excretion of ET-1 is increased in ADPKD patients, and may serve as a surrogate marker for ET-1 in renal tissue and a noninvasive marker of early kidney injury.

Autosomal dominant polycystic kidney disease (ADPKD) has significant extrarenal manifestations. Hypertension is a common complication, arises early in the course of the disease, and is implicated in the development of left ventricular hypertrophy. Patients with ADPKD are also at risk of other cardiovascular complications (Table 1).

This article reviews the timely diagnosis of these common ADPKD complications and how to manage them.

ADPKD ACCOUNTS FOR 10% OF END-STAGE RENAL DISEASE

ADPKD is a genetic condition characterized by multiple renal cysts.¹ Progressive enlargement of these cysts leads to a gradual decline in kidney function and eventually end-stage renal disease by the fifth or sixth decade of life.² Worldwide, about 12.5 million people have ADPKD, and it accounts for about 10% of cases of end-stage renal disease.^1,3,4

ADPKD has a variety of clinical presentations, including (in decreasing order of frequency) hypertension, flank pain, abdominal masses, urinary tract infection, renal failure, renal stones, and cerebrovascular accidents.²

Extrarenal complications are common and include hepatic cysts, hypertension, left ventricular hypertrophy, valvular heart disease, intracranial and extracranial aneurysms, pancreatic cysts, and diverticulosis.^1–5

Less-common complications are dissection of the aorta and the internal carotid, vertebral, and iliac arteries^6–10; aneurysm of the coronary, popliteal, and splenic arteries^11–14; atrial myxoma¹⁵; cardiomyopathy¹⁶; pericardial effusion¹⁷; intracranial arterial dolichoectasia¹⁸; arachnoid cysts²; and intraoperative inferior vena cava syndrome (normally in ADPKD patients,  pressure on the inferior vena cava results in compensatory sympathetic overactivity to maintain blood pressure), which occurs due to reduced sympathetic output under the influence of epidural or general anesthesia.¹⁹

Cardiovascular complications, especially cardiac hypertrophy and coronary artery disease, are now the leading cause of death in patients with ADPKD, as renal replacement therapy has improved and made death from end-stage renal disease less common.^20,21

HYPERTENSION IN ADPKD

Hypertension is the most frequent initial presentation of ADPKD, occurring in 50% to 75% of cases and usually preceding the onset of renal failure.^2,22 Hypertension is more common in male ADPKD patients, begins early in the course of the disease, and is diagnosed around the fourth decade of life.²¹

In a study in 2007, de Almeida et al²³ used 24-hour ambulatory blood pressure monitoring early in the course of ADPKD and found significantly higher systolic, diastolic, and mean 24-hour blood pressures in ADPKD patients who had normal in-office blood pressure than in normotensive controls. In addition, nighttime systolic, nighttime diastolic, and nighttime mean blood pressures were significantly higher in the ADPKD group. 

Hypertension is strongly associated with an accelerated decline in renal function to end-stage renal disease, development of left ventricular hypertrophy, and cardiovascular death.^20,24

Although a prospective study²⁵ showed a strong association between renal stones and hypertension in ADPKD, the relation between them is not clear. The incidence of renal stones is higher in hypertensive than in normotensive ADPKD patients, although evidence has to be established whether nephro­lithiasis is a risk factor for hypertension or the other way around.²⁵

Hypertension in ADPKD is multifactorial (Figure 1). The major factors associated with its development are increased activation of the renin-angiotensin-aldosterone system (RAAS); overexpression of endothelin receptor subtype A (ET-A) in cystic kidneys; increased production of endothelin 1 (ET-1); and sodium retention.^26–31

The renin-angiotensin-aldosterone system

Activation of the RAAS plays a major role in the development and maintenance of hypertension in ADPKD. This is thought to be mainly due to progressive enlargement of renal cysts, which causes renal arteriolar attenuation and ischemia secondary to pressure effects, which in turn activates the RAAS.^{26,30,32–34} Two studies in patients with normal renal function found that cyst growth and increasing kidney volume have a strong relationship with the development of hypertension and declining kidney function.^35,36

Ectopic secretion of RAAS components in polycystic kidneys has also been implicated in the development of hypertension, whereby renin, angiotensinogen, angiotensin-converting enzyme (ACE), angiotensin II, and angiotensin II receptors are produced in the epithelium of cysts and dilated tubules in polycystic kidneys.^37–39 Proximal renal cysts and tubules produce ectopic angiotensinogen, which is converted to angiotensin I by renin in distal renal cysts. Angiotensin I is converted to angiotensin II by ACE in distal tubules, which in turn stimulates angiotensin II receptors, causing sodium and water retention in distal tubules.³⁷ This may be responsible for hypertension in the initial stages; however, RAAS hyperactivity due to renal injury may predominate during later stages.³⁷

Increased RAAS activity also increases sympathetic output, which in turn raises catecholamine levels and blood pressure.³⁴ A study showed higher levels of plasma catecholamines in ADPKD hypertensive patients irrespective of renal function than in patients with essential hypertension.⁴⁰

ET-A receptor and ET-1

A few studies have shown that in ADPKD patients, increased density of ET-A receptors and overproduction of ET-1, a potent vasoconstrictor, play a significant role in the development of hypertension and gradual loss of kidney function due to cyst enlargement and interstitial scarring.^28,29 Ong et al²⁹ found that expression of ET-A receptors is increased in smooth muscle cells of renal arteries, glomerular mesangial cells, and cyst epithelia in ADPKD.

Studies in ADPKD patients with preserved renal function have linked high blood pressure to sodium retention and volume expansion.^30,31,41 However, this phenomenon reverses when there is significant renal impairment in ADPKD.

As evidence of this, a study demonstrated significantly more natriuresis in patients with renal failure due to ADPKD than in patients with a similar degree of renal failure due to chronic glomerulonephritis.³¹ Moreover, another study found that the prevalence of hypertension is higher in ADPKD patients than in those with other nephropathies with preserved renal function, but this association reverses with significant decline in kidney function.²²

MANAGING HYPERTENSION IN ADPKD

Early diagnosis of hypertension and effective control of it, even before ADPKD is diagnosed, is crucial to reduce cardiovascular mortality. Aggressive blood pressure control in the prehypertensive phase of ADPKD will also help reduce the incidence of left ventricular hypertrophy and mitral regurgitation and slow the progression of renal failure (Figure 2).

A meta-analysis⁴² revealed hypertension to be present in 20% of ADPKD patients younger than 21, and many of them were undiagnosed. This study also suggests that patients at risk of hypertension (ie, all patients with ADPKD)  should be routinely screened for it.

Ambulatory blood pressure monitoring may play an important role in diagnosing hypertension early in the prehypertensive stage of ADPKD.²³

Target blood pressures: No consensus

Two well-powered double-blind, placebo-controlled trials, known as HALT-PKD Study A and HALT-PKD Study B, tested the effects of 2 different blood pressure targets and of monotherapy with an ACE inhibitor vs combination therapy with an ACE inhibitor plus an angiotensin II receptor blocker (ARB) on renal function, total kidney volume, left ventricular mass index, and urinary albumin excretion in the early (estimated glomerular filtration rate [eGFR] > 60 mL/min) and late (eGFR 25–60 mL/min) stages of ADPKD, respectively.^43,44

HALT-PKD Study A⁴³ found that, in the early stages of ADPKD with preserved renal function, meticulous control of blood pressure (95–110/60–75 mm Hg) was strongly correlated with significant reductions in left ventricular mass index, albuminuria, and rate of total kidney volume growth without remarkable alteration in renal function compared with standard blood pressure control (120–130/70–80 mm Hg). However, no notable differences were observed between the ACE inhibitor and ACE inhibitor-plus-ARB groups.⁴³

Despite the evidence, universal consensus guidelines are lacking, and the available guidelines on hypertension management have different blood pressure goals in patients with chronic kidney disease.

The eighth Joint National Committee guideline of 2014 recommends a blood pressure goal of less than 140/90 mm Hg in patients with diabetic and nondiabetic chronic kidney disease.⁴⁵

The National Institute for Health and Care Excellence 2011 guideline recommends a blood pressure goal of less than 130/80 mm Hg in chronic kidney disease patients.⁴⁶

The European Society of Hypertension and European Society of Cardiology joint 2013 guideline recommends a systolic blood pressure goal of less than 140 mm Hg in diabetic and nondiabetic patients with chronic kidney disease.⁴⁷

The 2016 Kidney Health Australia-Caring for Australians With Renal Impairment guideline for diagnosis and management of ADPKD⁴⁸ recommends a lower blood pressure goal of 96–110/60–75 mm Hg in patients with an eGFR greater than 60 mL/min/1.73 m² who can tolerate it without side effects, which is based on the findings of HALT-PKD Study A.⁴³

Helal et al recommend that blood pressure be controlled to less than 130/80 mm Hg, until there is more evidence for a safe and effective target blood pressure goal in ADPKD patients.⁴⁹

We recommend a target blood pressure less than 110/75 mm Hg in hypertensive ADPKD patients with preserved renal function who can tolerate this level, and less than 130/80 mm Hg in ADPKD patients with stage 3 chronic kidney disease. These targets  can be achieved with ACE inhibitor or ARB monotherapy.^43,44 However, no studies have established the safest lower limit of target blood pressure in ADPKD.

ACE inhibitors, ARBs are mainstays

Mainstays of antihypertensive drug therapy in ADPKD are ACE inhibitors and ARBs.

HALT-PKD Study B⁴⁴ demonstrated that, in the late stages of ADPKD, target blood pressure control (110–130/70–80 mm Hg) can be attained with ACE inhibitor monotherapy or with an ACE inhibitor plus an ARB, but the latter produced no additive benefit.

Patch et al,⁵⁰ in a retrospective cohort study, showed that broadening the spectrum of antihypertensive therapy decreases mortality in ADPKD patients. Evaluating ADPKD patients from the UK General Practice Research Database between 1991 and 2008, they found a trend toward lower mortality rates as the number of antihypertensive drugs prescribed within 1 year increased. They also observed that the prescription of RAAS-blocking agents increased from 7% in 1991 to 46% in 2008.⁵⁰ 

However, a 3-year prospective randomized double-blind study compared the effects of the ACE inhibitor ramipril and the beta-blocker metoprolol in hypertensive ADPKD patients.⁵¹ The results showed that effective blood pressure control could be achieved in both groups with no significant differences in left ventricular mass index, albuminuria, or kidney function.⁵¹

Treatment strategies

Lifestyle modification is the initial approach to the management of hypertension before starting drug therapy. Lifestyle changes include dietary salt restriction to less than 6 g/day, weight reduction, regular exercise, increased fluid intake (up to 3 L/day or to satisfy thirst), smoking cessation, and avoidance of caffeine.^47–49

ACE inhibitors are first-line drugs in hypertensive ADPKD patients.

ARBs can also be considered, but there is no role for dual ACE inhibitor and ARB therapy.^43,48 A study found ACE inhibitors to be more cost-effective and to decrease mortality rates to a greater extent than ARBs.⁵²

Beta-blockers or calcium channel blockers should be considered instead if ACE inhibitors and ARBs are contraindicated,  or as add-on drugs if ACE inhibitors and ARBs fail to reduce blood pressure adequately.^48,49

Diuretics are third-line agents. Thiazides are preferred in ADPKD patients with normal renal function and loop diuretics in those with impaired renal function.⁴⁹

LEFT VENTRICULAR HYPERTROPHY IN ADPKD

Increased left ventricular mass is an indirect indicator of untreated hypertension, and it often goes unnoticed in patients with undiagnosed ADPKD. Left ventricular hypertrophy is associated with arrhythmias and heart failure, which contribute significantly to cardiovascular mortality and adverse renal outcomes.^20,24

A 5-year randomized clinical trial by Cadnapaphornchai et al³⁶ in ADPKD patients between 4 and 21 years of age showed strong correlations between hypertension, left ventricular mass index, and kidney volume and a negative correlation between left ventricular mass index and renal function.

Several factors are thought to contribute to left ventricular hypertrophy in ADPKD (Figure 1).

Hypertension. Two studies of 24-hour ambulatory blood pressure monitoring showed that nocturnal blood pressures decreased less in normotensive and hypertensive ADPKD patients than in normotensive and hypertensive controls.^23,53 This persistent elevation of nocturnal blood pressure may contribute to  the development and progression of left ventricular hypertrophy.

On the other hand, Valero et al⁵⁴ reported that the left ventricular mass index was strongly associated with ambulatory systolic blood pressure rather than elevated nocturnal blood pressure in ADPKD patients compared with healthy controls.

FGF23. High levels of fibroblast growth factor 23 (FGF23) have been shown to be strongly associated with left ventricular hypertrophy in ADPKD. Experimental studies have shown that FGF23 is directly involved in the pathogenesis of left ventricular hypertrophy through stimulation of the calcineurin-nuclear factor of activated T cells pathway.

Faul et al⁵⁵ induced cardiac hypertrophy in mice that were deficient in klotho (a transmembrane protein that increases FGF23 affinity for FGF receptors) by injecting FGF23 intravenously.

Yildiz et al⁵⁶ observed higher levels of FGF23 in hypertensive and normotensive ADPKD patients with normal renal function than in healthy controls. They also found a lower elasticity index in the large and small arteries in normotensive and hypertensive ADPKD patients, which accounts for vascular dysfunction. High FGF23 levels may be responsible for the left ventricular hypertrophy seen in normotensive ADPKD patients with preserved renal function.

Polymorphisms in the ACE gene have been implicated in the development of cardiac hypertrophy in ADPKD.

Wanic-Kossowska et al⁵⁷ studied the association between ACE gene polymorphisms and cardiovascular complications in ADPKD patients. They found a higher prevalence of the homozygous DD genotype among ADPKD patients with end-stage renal disease than in those in the early stages of chronic kidney disease in ADPKD. Also, the DD genotype has been shown to be more strongly associated with left ventricular hypertrophy and left ventricular dysfunction than other (II or ID) genotypes. These findings suggest that the DD genotype carries higher risk for the development of end-stage renal disease, left ventricular hypertrophy, and other cardiovascular complications.

Preventing and halting progression of left ventricular hypertrophy primarily involves effective blood pressure control, especially in the early stages of ADPKD (Figure 2).

A 7-year prospective randomized trial in ADPKD patients with established hypertension and left ventricular hypertrophy proved that aggressive (< 120/80 mm Hg) compared with standard blood pressure control (135–140/85–90 mm Hg) significantly reduces left ventricular mass index. ACE inhibitors were preferred over calcium channel blockers.⁵⁸

HALT-PKD Study A showed that a significant decrease in left ventricular mass index can be achieved by aggressive blood pressure control (95–110/60–75 mm Hg) with an ACE inhibitor alone or in combination with an ARB in the early stages of ADPKD with preserved renal function.⁴³

A 5-year randomized clinical trial in children with borderline hypertension treated with an ACE inhibitor for effective control of blood pressure showed no change in left ventricular mass index or renal function.^36,59

These results support starting ACE inhibitor therapy early in the disease process when blood pressure is still normal or borderline to prevent the progression of left ventricular hypertrophy or worsening kidney function.

Since FGF23 is directly involved in the causation of left ventricular hypertrophy, FGF receptors may be potential therapeutic targets to prevent left ventricular hypertrophy in ADPKD. An FGF receptor blocker was shown to decrease left ventricular hypertrophy in rats with chronic kidney disease without affecting blood pressure.⁵⁵

INTRACRANIAL ANEURYSM IN ADPKD

Intracranial aneurysm is the most dangerous complication of ADPKD. When an aneurysm ruptures, the mortality rate is 4% to 7%, and 50% of survivors are left with residual neurologic deficits.^5,60,61

In various studies, the prevalence of intracranial aneurysm in ADPKD ranged from 4% to 41.2%, compared with 1% in the general population.^5,62,63 On follow-up ranging from 18 months to about 10 years, the incidence of new intracranial aneurysm was 2.6% to 13.3% in patients with previously normal findings on magnetic resonance angiography and 25% in patients with a history of intracranial aneurysm.^62,64,65

The most common sites are the middle cerebral artery (45%), internal carotid artery (40.5%), and anterior communicating artery (35.1%).⁶⁶ (The numbers add up to more than 100% because some patients have aneurysms in more than 1 site.) The mean size of a ruptured aneurysm was 6 mm per a recent systematic review.⁶⁶ Intracranial aneurysms 6 mm or larger are at highest risk of rupture.⁶⁶

SCREENING FOR INTRACRANIAL ANEURYSM

Timely screening and intervention for intracranial aneurysm is crucial to prevent death from intracranial hemorrhage.

Currently, there are no standard guidelines for screening and follow-up of intracranial aneurysm in ADPKD patients. However, some recommendations are available from the ADPKD Kidney Disease Improving Global Outcomes Controversies Conference³ and Kidney Health Australia—Caring for Australasians With Renal Impairment ADPKD guidelines⁶⁷ (Figure 3).

Imaging tests

Magnetic resonance angiography (MRA) with gadolinium enhancement and computed tomographic angiography (CTA) are recommended for screening in ADPKD patients with normal renal function,⁶⁷ but time-of-flight MRA without gadolinium is the imaging test of choice because it is noninvasive and poses no risk of nephrotoxicity or contrast allergy.^3,68 Further, gadolinium should be avoided in patients whose eGFR is 30 mL/min/1.73 m² or less because of risk of nephrogenic systemic sclerosis and fibrosis.^67,68

The sensitivity of time-of-flight MRA screening for intracranial aneurysm varies depending on the size of aneurysm; 67% for those less than 3 mm, 79% for those 3 to 5 mm, and 95% for those larger than 5 mm.⁶⁹ The sensitivity of CTA screening is 95% for aneurysms larger than 7 mm and 53% for those measuring 2 mm.^70,71 The specificity of CTA screening was reported to be 98.9% overall.⁷¹

When to screen

Screening for intracranial aneurysm is recommended at the time of ADPKD diagnosis for all high-risk patients, ie, those who have a family history of intracranial hemorrhage or aneurysm in an affected first-degree relative.⁶⁷ It is also recommended for ADPKD patients with a history of sudden-onset severe headache or neurologic symptoms.⁶⁷ A third group for whom screening is recommended is ADPKD patients who have no family history of intracranial aneurysm or hemorrhage but who are at risk of poor outcome if an intracranial aneurysm ruptures (eg, those undergoing major elective surgery, with uncontrolled blood pressure, on anticoagulation, with a history of or current smoking, and airline pilots).⁶⁷

Patients found to have an intracranial aneurysm on screening should be referred to a neurosurgeon and should undergo repeat MRA or CTA imaging every 6 to 24 months.³ High-risk ADPKD patients with normal findings on initial screening should have repeat MRA or CTA screening in 5 to 10 years unless they suffer from sudden-onset severe headache or neurologic symptoms.^65,67

Both smoking and high blood pressure increase the risk of formation and growth of intracranial aneurysm. Hence, meticulous control of blood pressure and smoking cessation are recommended in ADPKD patients.^3,67

CARDIAC VALVULAR ABNORMALITIES IN ADPKD

Of the valvular abnormalities that complicate ADPKD, the more common ones are mitral valve prolapse and mitral and aortic regurgitation. The less common ones are tricuspid valve prolapse and tricuspid regurgitation.^72–74

The pathophysiology underlying these valvular abnormalities is unclear. However, defective collagen synthesis and myxomatous degeneration have been demonstrated in histopathologic examination of affected valvular tissue.⁷⁵ Also, ACE gene polymorphism, especially the DD genotype, has been shown to be associated with cardiac valvular calcifications and valvular insufficiency.⁵⁷

Lumiaho et al⁷² found a higher prevalence of mitral valve prolapse, mitral regurgitation, and left ventricular hypertrophy in patients with ADPKD type 1 (due to abnormalities in PDK1) than in unaffected family members and healthy controls. The investigators speculated that mitral regurgitation is caused by the high blood pressure observed in ADPKD type 1 patients, since hypertension causes left ventricular hypertrophy and left ventricular dilatation. The severity of renal failure was related to mitral regurgitation but not mitral valve prolapse.

Similarly, Gabow et al²⁴ showed that there is no significant relationship between mitral valve prolapse and progression of renal disease in ADPKD.

Interestingly, Fick et al²⁰ found that mitral valve prolapse has no significant effect on cardiovascular mortality.

Atherosclerosis sets in early in ADPKD, resulting in coronary artery disease and adverse cardiovascular outcomes.

Coronary flow velocity reserve is the ability of coronary arteries to dilate in response to myocardial oxygen demand. Atherosclerosis decreases this reserve in ADPKD patients, as shown in several studies.

Turkmen et al, in a series of studies,^76–78 found that ADPKD patients had significantly less coronary flow velocity reserve, thicker carotid intima media (a surrogate marker of atherosclerosis), and greater insulin resistance than healthy controls. These findings imply that atherosclerosis begins very early in the course of ADPKD and has remarkable effects on cardiovascular morbidity and mortality.⁷⁶

Aneurysm. Although the risk of extracranial aneurysm is higher with ADPKD, coronary artery aneurysm is uncommon. The pathogenesis of coronary aneurysm has been linked to abnormal expression of the proteins polycystin 1 and polycystin 2 in vascular smooth muscle.^11,79 The PKD1 and PKD2 genes encode polycystin 1 and 2, respectively, in ADPKD. These polycystins are also expressed in the liver, kidneys, and myocardium and are involved in the regulation of intracellular calcium, stretch-activated ion channels, and vascular smooth muscle cell proliferation and apoptosis.^11,16 Abnormally expressed polycystin in ADPKD therefore has an impact on arterial wall integrity, resulting in focal medial defects in the vasculature that eventually develop into micro- and macroaneurysms.¹¹

Hadimeri et al⁷⁹ found a higher prevalence of coronary aneurysm and ectasia in ADPKD patients than in controls. Most coronary aneurysms are smaller than 1 cm; however, a coronary aneurysm measuring 4 cm in diameter was found at autopsy of an ADPKD patient.¹¹

Spontaneous coronary artery dissection is very rare in the general population, but Bobrie et al reported a case of it in an ADPKD patient.⁹

ATRIAL MYXOMA, CARDIOMYOPATHY, AND PERICARDIAL EFFUSION IN ADPKD

Atrial myxoma in ADPKD patients has been described in 2 case reports.^15,80 However, the association of atrial myxoma with ADPKD is poorly understood and may be a coincidental finding.

Cardiomyopathy in ADPKD has been linked to abnormalities in the intracellular calcium pathway, although a clear picture of its involvement has yet to be established.

Paavola et al¹⁶ described the pathophysiology of ADPKD-associated cardiomyopathy in PKD2 mutant zebrafish lacking polycystin 2. These mutants showed decreased cardiac output and had atrioventricular blocks. The findings  were attributed to abnormal intracellular calcium cycling. These findings correlated well with the frequent finding of idiopathic dilated cardiomyopathy in ADPKD patients, especially with PKD2 mutations.¹⁶ Also, 2 cases of dilated cardiomyopathy in ADPKD have been reported and thought to be related to PKD2 mutations.^81,82

Pericardial effusion. Even though the exact pathophysiology of pericardial effusion in ADPKD is unknown, it has been theorized to be related to defects in connective tissue and extracellular matrix due to PKD1 and PKD2 mutations. These abnormalities increase the compliance and impair the recoil capacity of connective tissue, which results in unusual distention of the parietal pericardium. This abnormal distention of the parietal pericardium together with increased extracellular volume may lead to pericardial effusion.¹⁷

Qian et al¹⁷ found a higher prevalence of pericardial effusion in ADPKD patients. It was generally asymptomatic, and the cause was attributed to these connective tissue and extracellular matrix abnormalities.

EMERGING THERAPIES AND TESTS

Recent trials have investigated the effects of vasopressin receptor antagonists, specifically V2 receptor blockers in ADPKD and its complications.

Tolvaptan has been shown to slow the rate of increase in cyst size and total kidney volume.^83,84 Also, a correlation between kidney size and diastolic blood pressure has been observed in ADPKD patients.⁸⁵ Reducing cyst volume may reduce pressure effects and decrease renal ischemia, which in turn may reduce RAAS activation; however, the evidence to support this hypothesis is poor. A major clinical trial of tolvaptan in ADPKD patients showed no effect on blood pressure control, but the drug slowed the rate of increase in total kidney volume and fall in eGFR.⁸³

Endothelin receptor antagonists are also in the preliminary stage of development for use in ADPKD. The effects of acute blockade of the renal endothelial system with bosentan were  investigated in animal models by Hocher et al.²⁸ This study showed a greater reduction in mean arterial pressure after bosentan administration, resulting in significantly decreased GFR and renal blood flow. Nonetheless, the mean arterial pressure-lowering effect of bosentan was more marked than the reductions in GFR and renal blood flow.

Raina et al,⁸⁶ in a pilot cross-sectional analysis, showed that urinary excretion of ET-1 is increased in ADPKD patients, and may serve as a surrogate marker for ET-1 in renal tissue and a noninvasive marker of early kidney injury.

To the Editor: In their Clinical Picture article in the February 2017 issue, Barbaryan et al¹ describe brain lesions in a young woman with human immunodeficiency virus infection who presented with seizures. Figure 3 illustrates Grocott-Gomori methenamine silver (GMS)-positive fungal organisms in a brain biopsy. The organisms appear helmet-shaped and crescent-shaped and contain an intracystic dot, morphologic features of Pneumocystis jiroveci cysts.² We could not appreciate features of Histoplasma yeasts (smaller yeasts with diameter of 3 to 5 μm, oval to tapered shape, and narrow-based budding).

The distinction between the two organisms can occasionally be challenging because there is some degree of overlap in size and shape, and both are GMS-positive. It is interesting that in the current case, serologic studies for Histoplasma were positive. Multiple infections with opportunistic organisms are not uncommon in severely immunocompromised individuals, and it is possible that the patient may also have had concurrent histoplasmosis. Brain lesions caused by Pneumocystis, although rare, have been previously reported.^3–5 Immunohistochemistry for Pneumocystis may be of interest in this very unusual case.

[Editor’s note: Letters that comment on articles published in the Journal are sent to the author(s) for response. In this case, the authors felt that the letter did not require a reply.]

To the Editor: In their Clinical Picture article in the February 2017 issue, Barbaryan et al¹ describe brain lesions in a young woman with human immunodeficiency virus infection who presented with seizures. Figure 3 illustrates Grocott-Gomori methenamine silver (GMS)-positive fungal organisms in a brain biopsy. The organisms appear helmet-shaped and crescent-shaped and contain an intracystic dot, morphologic features of Pneumocystis jiroveci cysts.² We could not appreciate features of Histoplasma yeasts (smaller yeasts with diameter of 3 to 5 μm, oval to tapered shape, and narrow-based budding).

The distinction between the two organisms can occasionally be challenging because there is some degree of overlap in size and shape, and both are GMS-positive. It is interesting that in the current case, serologic studies for Histoplasma were positive. Multiple infections with opportunistic organisms are not uncommon in severely immunocompromised individuals, and it is possible that the patient may also have had concurrent histoplasmosis. Brain lesions caused by Pneumocystis, although rare, have been previously reported.^3–5 Immunohistochemistry for Pneumocystis may be of interest in this very unusual case.

[Editor’s note: Letters that comment on articles published in the Journal are sent to the author(s) for response. In this case, the authors felt that the letter did not require a reply.]

To the Editor: In their Clinical Picture article in the February 2017 issue, Barbaryan et al¹ describe brain lesions in a young woman with human immunodeficiency virus infection who presented with seizures. Figure 3 illustrates Grocott-Gomori methenamine silver (GMS)-positive fungal organisms in a brain biopsy. The organisms appear helmet-shaped and crescent-shaped and contain an intracystic dot, morphologic features of Pneumocystis jiroveci cysts.² We could not appreciate features of Histoplasma yeasts (smaller yeasts with diameter of 3 to 5 μm, oval to tapered shape, and narrow-based budding).

The distinction between the two organisms can occasionally be challenging because there is some degree of overlap in size and shape, and both are GMS-positive. It is interesting that in the current case, serologic studies for Histoplasma were positive. Multiple infections with opportunistic organisms are not uncommon in severely immunocompromised individuals, and it is possible that the patient may also have had concurrent histoplasmosis. Brain lesions caused by Pneumocystis, although rare, have been previously reported.^3–5 Immunohistochemistry for Pneumocystis may be of interest in this very unusual case.

[Editor’s note: Letters that comment on articles published in the Journal are sent to the author(s) for response. In this case, the authors felt that the letter did not require a reply.]

For a patient struggling with opioid addiction, opioid agonist therapy with methadone or buprenorphine can reduce craving and opioid use and may even save his or her life. But many clinicians are unfamiliar with this evidence-based treatment,^1,2 which is best started early in the course of addiction.³

See related editorial

This article outlines the pharmacology of these drugs, their clinical uses, and the challenges of using them to treat opioid addiction.

DIAGNOSTIC CRITERIA

Opioid addiction, formally known as opioid use disorder, is a pattern of opioid misuse leading to clinically significant impairment in multiple areas of life. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, lists 11 diagnostic criteria, but only 2 need to be present within the past year to make the diagnosis⁴:

• Taking opioids longer or in higher doses than was intended
• A persistent desire or unsuccessful efforts to cut down or control opioid use
• Spending a great deal of time obtaining, using, or recovering from using opioids
• Craving opioids
• Repeatedly failing to fulfill obligations at work, school, or home due to opioid use
• Continuing to use opioids even though it causes or exacerbates social or interpersonal problems
• Giving up or curtailing important social, occupational, or recreational activities because of opioid use
• Repeatedly using opioids in situations in which it is physically hazardous
• Continuing to use opioids despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the substance
• Tolerance
• Withdrawal.

Recent estimates indicate that 2.23 million people in the United States have opioid use disorder (426,000 with heroin and 1.8 million with prescription opioids).⁵

Progression from prescription opioids to heroin

We have observed that many patients with opioid use disorder start by misusing prescription opioids. Over time, tolerance can develop, which drives patients to use higher and higher doses.⁶

As the addiction progresses, a subset of prescription opioid users advances to using heroin, which is typically less expensive and easier to obtain.⁷ Most patients start with the intranasal route but eventually inject it intravenously.^6,7

For many addicts, heroin use has medical consequences such as hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection, psychiatric problems such as depression and anxiety, and illegal activities such as theft and sex work.⁸ People who use heroin appear to have more severe addiction and a lower socioeconomic status than prescription opioid users.^9–11 But recently, a growing number of middle class individuals are becoming addicted to heroin.¹²

METHADONE

Methadone is a long-acting synthetic opioid that functions as a full agonist on the mu-opioid receptor. The drug binds, occupies, and stimulates the receptor, preventing withdrawal symptoms and reducing opioid cravings for at least 24 hours.¹³

Adverse effects of methadone

The most common adverse effects include lightheadedness, dizziness, sedation, nausea, vomiting, and sweating.¹⁴ Other adverse effects:

Unintentional overdose. The risk is serious, as a single 30-mg dose can be fatal in people who are opioid-naïve.¹³

QTc prolongation, which can lead to torsade de pointes. This risk, which is dose-related, must be taken into consideration in patients who have any cardiac symptoms (eg, syncope, arrhythmia), pathology (familial QT prolongation), or other risk factors for QTc prolongation (eg, hypokalemia, QTc-prolonging medications).¹⁵

Respiratory depression, which can be fatal. This dose-related risk is heightened during the first 4 weeks of treatment if titration is too rapid or if methadone is used in combination with other drugs that cause central nervous system or respiratory depression.^13,14

Starting methadone

To prevent respiratory depression and death related to rapid induction, the general rule is to start methadone at a low daily dose (20–30 mg) depending on the patient’s withdrawal symptoms.¹⁴ During this period, patients need to be closely monitored and educated on the perils of concomitant use of central nervous system depressants.¹⁴

In most patients, the dose is titrated up until their withdrawal symptoms and cravings are eliminated, which generally requires 60 to 120 mg daily.¹⁴ Hepatic and renal impairment, pregnancy, and advanced age can alter methadone pharmacokinetics and may therefore necessitate dose adjustment.

BUPRENORPHINE

Buprenorphine is an alkaloid thebaine opioid derivative that acts as a partial mu-opioid agonist and a kappa antagonist.¹⁶ Like methadone, buprenorphine is used to manage cravings and withdrawal symptoms.¹⁶ Dosages of 4 to 16 mg (up to 32 mg) per day of buprenorphine are usually required to adequately control opioid cravings.¹⁶

Sublingual and subdermal products

Buprenorphine is currently available in the United States in sublingual and subdermal formulations.^16,17

Sublingual buprenorphine is usually combined with naloxone in a 4:1 ratio to deter intravenous use. Intravenous injection of the combination product can precipitate withdrawal due to the antagonist action of naloxone. (Taken orally or sublingually, naloxone is poorly absorbed and has little or no clinical effect.) Buprenorphine-naloxone is available in tablets, a sublingual film strip, and a buccal film strip. Buprenorphine is also available by itself in a sublingual formulation.

The US Food and Drug Administration has approved a buprenorphine subdermal implant, Probuphine. Four rods, about 1 inch long, are placed under the skin in the inner aspect of the upper arm and provide the equivalent of 8 mg of buprenorphine daily for 6 months.¹⁷ However, this method is formulated only for maintenance treatment and cannot be used for induction. Additionally, it is recommended that the implants be surgically removed at the end of 6 months, after which another set of implants can be inserted in the other arm or the patient can switch to sublingual therapy, depending on the clinical situation and patient preference.¹⁷

Generally safer than methadone

Buprenorphine works on the same receptor as methadone and therefore has a similar side effect profile. However, buprenorphine has a ceiling effect, which greatly reduces the risk of fatal respiratory depression.¹⁸ It also does not cause clinically significant QTc prolongation and is preferable in patients who have cardiac risk factors.¹⁸

Another advantage is that buprenorphine has fewer identified medication interactions than methadone.¹⁸ Further, induction of buprenorphine in patients with opioid use disorder has been shown to be safer than methadone.¹⁹

Although buprenorphine has been found to be 6 times safer than methadone with regard to overdose among the general population,²⁰ it can still cause fatal intoxication if used in combination with central nervous system depressants.²¹

Buprenorphine has been also associated with hepatotoxicity, though the risk of new-onset liver disease appears to be low.²²

Besides methadone and buprenorphine, the only other approved option for treating opioid use disorder is the opioid antagonist naltrexone.

Naltrexone has significantly less abuse potential, as it provides no euphoria, but patients do not like it. Even with the long-acting formulation (Vivitrol), naltrexone treatment is significantly less effective than methadone or buprenorphine.^23–25 Further, although naltrexone is not a controlled substance and so does not face the same scrutiny as the agonist therapies, there are other significant barriers. Additional information on naltrexone is presented in reviews by Modesto-Lowe and Van Kirk²⁴ and Woody.²⁵

OBSTACLES TO TREATMENT

People hold conflicting views about opioid agonist therapy. Some believe that “trading one drug for another” is not a legitimate therapeutic strategy, and they may feel ashamed of being on maintenance therapy.²⁶ Similarly, some argue that the answer to establishing stable abstinence does not lie simply in prescribing medications.

The contrary argument is that these medications, if used appropriately, confer many benefits such as reducing the medical and psychosocial sequelae of opioid addiction.¹⁸ In fact, properly treated patients no longer meet the diagnostic criteria of opioid use disorder, and both methadone and buprenorphine are on the World Health Organization’s (WHO) list of essential medicines.²⁷

Despite endorsement by the WHO, the stigma attached to the opioid agonists has been difficult to overcome. Patients with opioid use disorder may be viewed with distrust by healthcare providers and often do not feel welcome in healthcare settings or in self-help recovery groups.²⁸

Barriers to methadone therapy

Federal regulations on methadone prescribing and use were established to promote patient safety and decrease diversion, but they may also complicate access to care.²⁹ They stipulate that to qualify for methadone maintenance, patients need to demonstrate opioid addiction for 1 year, except for pregnant women and those who have been incarcerated in the past 6 months. Patients under the age of 18 must have 2 documented failed treatment episodes as well as approval by a guardian to receive treatment.

Inconvenience. Methadone can be prescribed for opioid dependence only by an accredited treatment program. Patients must therefore travel to the clinic and wait to be evaluated on a daily basis for a minimum of 90 days. Only after they demonstrate consistent responsible behavior and negative results on urine testing do they become eligible to take methadone home.²⁹ If a patient is to travel out of the area during the initial 90 days of treatment, he or she must make arrangements in advance to find a clinic that will provide a “guest dose.”

The inconvenience arising from the regulations may deter some patients from seeking methadone therapy. In spite of this, once patients are started on methadone, more of them continue treatment than with buprenorphine.¹⁸ A proposed reason is that methadone is a potent full opioid agonist and therefore relieves withdrawal symptoms and craving more effectively than buprenorphine, which is a partial agonist.³⁰ Another possible reason is the higher level of supervision afforded by methadone clinics, which require daily contact for at least 90 days. 

Safety concerns arise from methadone diversion, as illicit use may have lethal consequences. In the past decade, deaths from methadone overdose have risen significantly, most of them due to respiratory depression or torsade de pointes.¹³ However, most cases of diversion and overdose involve methadone that is prescribed for pain by individual practitioners and not from maintenance programs.¹³

Advantages of buprenorphine

Together, methadone’s lethality, stigma, and inconvenience may contribute to patients preferring buprenorphine.³¹

The regulations governing buprenorphine’s use are less restrictive than those with methadone. For example, patients must have a diagnosis of opioid addiction to be prescribed buprenorphine, but they are not required to carry the diagnosis for a year before treatment.³¹ Additionally, they do not need to travel to a federally approved opioid treatment center daily and can receive buprenorphine directly from a physician in an outpatient setting.

Under the Drug Abuse Treatment Act (DATA) of 2000, any physician can apply for a waiver to prescribe and dispense buprenorphine in his or her office. To qualify for an initial waiver, physicians must either obtain certification in the fields of addiction medicine or addiction psychiatry or complete an approved 8-hour training session.³² Each physician starts with a maximum of 30 patients, but can apply to treat up to 100 patients after 1 year and eventually up to 275 patients. Physicians must document every buprenorphine prescription they write and be able to refer patients for counseling.³¹

As of February 2017, nurse practitioners and physician assistants can also apply for a DATA 2000 waiver. All waivered providers are subject to unannounced visits from the Drug Enforcement Administration once every 5 years.³²

While there are no federal restrictions on the amount of buprenorphine that can be dispensed, some states and some insurance companies have placed restrictions on dose or length of treatment.³³ Buprenorphine patients can fill their prescriptions at any pharmacy and are permitted to bring their medication home, which improves access to care. However, office-based outpatient treatment is not without risk, and preventing buprenorphine diversion remains a challenge.³⁴

‘Lending’ buprenorphine is a felony

Addicts have illegally used buprenorphine to self-treat opioid withdrawal, craving, and dependence.³⁵ Its misuse has also been coupled with self-treatment of conditions that include depression and pain.³⁶

A survey found that 83.7% of patients deem buprenorphine diversion to be appropriate; further, most patients said they consider it unethical to withhold prescribed buprenorphine from individuals showing symptoms of withdrawal.³⁴ Physicians who prescribe buprenorphine must inform their patients that even “lending” or giving away their medication is a felony.

Prescribing physicians must also be diligent about monitoring for signs of diversion such as inconsistent urine toxicology screens, “lost” medication, and requests for early refills or escalating doses.³⁷

In addition to federal regulations, we propose a 4-step approach to evaluate eligibility for opioid replacement therapy based on existing guidelines.^37–39

Step 1: History and physical examination

The history should give particular attention to the patient’s cardiac, pulmonary, and hepatic status, with consideration of the risks of any medical comorbidities (eg, bacterial endocarditis, HIV and HCV infection) that might influence treatment.³⁷

It is also essential to evaluate for any contraindications or drug interactions before prescribing methadone or buprenorphine.³⁸

Contraindications to methadone maintenance include⁴⁰:

• Cor pulmonale
• Methadone hypersensitivity
• Pseudomembranous colitis
• Selegiline use (due to risk of serotonin syndrome)
• Ileum paralyticus.

Contraindications to buprenorphine use include:

• Hypersensitivity to naloxone or buprenorphine
• Impaired liver function (due to the risk of inadvertent overdose associated with slowed metabolism).

Concurrent use of alcohol or illicit benzodiazepines is a relative contraindication to both methadone and buprenorphine due to the risk of respiratory depression and overdose.³⁷ Likewise, avoid coprescribing opioid agonists and benzodiazepines whenever possible. Obtain a complete list of current medications and query a prescription-monitoring database to determine whether any controlled substances are currently prescribed.³⁷

During the physical examination, look for stigmata of intravenous drug use such as track marks or abscesses³⁷ and document any physical findings consistent with intoxication or withdrawal. Patients must be completely detoxed or in withdrawal before beginning buprenorphine induction; premature induction can precipitate withdrawal.³⁸

A discussion of pregnant patients with opioid use disorder is beyond the scope of this paper. However, it is incumbent on the prescriber to inquire whether the client is pregnant or intends to become pregnant and what birth control methods are in place.

Step 2: Assess psychiatric status

Assessment of the patient’s psychiatric status, including an assessment of alcohol and other drug use, will help determine his or her eligibility for opioid agonists.³⁷ To prepare for the need to manage patients with psychiatrically complex issues, it is helpful to develop relationships with addiction specialists and psychiatrists who are familiar with opioid replacement therapy in your area. This will make it easier to collaborate on patients’ care.

Ask all patients directly about suicidal or homicidal ideation. Any patient with active suicidal or homicidal ideation should be assessed for need of immediate hospitalization by a psychiatrist or another qualified mental health professional. Patients with a history of suicidal ideation should be monitored closely by a mental health professional throughout treatment.³⁷

Many if not most patients with opioid use disorder have concurrent psychiatric disorders, and the interplay between these disorders is complex.^40,41 Depression, for example, can precede and even precipitate drug use (an observation supporting the “self-medication theory”).⁴² If the underlying depressive disorder is not addressed, relapse is nearly inevitable.

It has also been shown that both chronic opioid use and withdrawal can exacerbate aversive emotional states. This escalation of symptoms may result from the pharmacologic effects of opioids or from psychosocial sequelae that can arise from chronic opioid use.⁴¹ In this situation, maintaining abstinence can lead to resolution of depressive symptoms. As depression and opioid use can occur together, successful treatment requires equal attention to both illnesses.

Other common comorbidities in patients with opioid use disorder include posttraumatic stress disorder, attention deficit hyperactivity disorder, antisocial personality disorder, and concurrent substance abuse disorders.⁴³ The confluence of antisocial personality disorder is particularly important, as patients with antisocial personality disorder display disruptive and maladaptive behaviors.

Identify any psychotropic medication that is prescribed and check carefully for drug interactions. This applies especially to methadone, as many psychiatric medications also prolong the QT interval. Moreover, patients may not be forthcoming about the use of psychiatric medication.

Find out whether the patient is using any other addictive substances, particularly those that affect the central nervous system, as those who use fentanyl, benzodiazepines, or alcohol are at the highest risk of overdose.³¹ Often the best option for those with concurrent substance use disorders is inpatient detoxification followed by residential rehabilitation care. Either buprenorphine or methadone can then be initiated upon return to an outpatient setting.

Step 3: Assess psychosocial status

To what extent do the patient’s home environment and support systems promote a drug-free lifestyle? Unfortunately, the psychosocial status of many of these patients is fragile, and they may live in areas where illicit drugs are readily available (which can be urban, suburban, or rural), making it difficult to stay substance-free.³⁸

Generally, lifestyle modifications are needed to transform maladaptive behaviors and promote an environment conducive to long-term recovery. Referrals to social services to address housing, vocational needs, and entitlements may be helpful.³⁹

Step 4: Assess readiness to change

According to one model, people go through 5 stages when changing a behavior: precontemplation, contemplation, preparation for action, action, and maintenance.⁴³ In general, the further along the stages a patient is, the more appropriate he or she is for office-based treatment with buprenorphine.³⁹

The level of change can be assessed with tools such as Stages of Change Readiness and Treatment Eagerness Scale (SOCRATES). Use of stage-specific strategies may enhance a patient’s readiness to cease opioid use.⁴³

Precontemplation. Those in the precontemplation stage are not ready to think about changing their behavior.⁴³ They may be unaware of or unwilling to consider the risks associated with their opioid use and resistant to the idea of quitting. Engagement with opioid agonists for individuals in this stage is low and dropout rates are likely high.

Thus, the proper approach for “precontemplators” is to help them develop some ambivalence about their opioid use. One tactic is to involve the patient in a discussion of the personal benefits and risks of opioid use.

Contemplation. Individuals in the contemplation stage have begun to weigh the costs and benefits of opioid use and express ambivalence about it.⁴⁴ Because the patient is willing to explore the risks of ongoing use and consider the benefits of treatment, the goal in this stage is to elicit a commitment from the individual to seek treatment.

Preparation. The person in this stage moves from thinking about treatment to planning what action to take.⁴⁵ As the individual prepares to enter treatment, indecision tends to resurface, as well as self-doubt about his or her ability to change. During this stage, it is important for the provider to spell out goals (abstinence) and strategies (eg, counseling, medication) and enhance a sense of self-efficacy.

Action and maintenance. Patients in these stages engage in treatment and employ new strategies to abstain from opioid use. Maintaining these behaviors can be a daily struggle. Expressing confidence in the patient’s ability to abstain from use will support his or her progress. Behavioral interventions such as strategic avoidance of triggers and engagement in alternative activities (eg, support groups, exercise, faith-based practices) will help to maintain abstinence.

A CHRONIC CONDITION

Opioid use disorder, like many chronic illnesses, requires long-term attention to attain successful patient outcomes. The opioid agonists methadone and buprenorphine are the mainstay of treatment for it, conferring benefits such as reducing opioid use and preventing relapse.

Candidates for opioid agonist therapy should undergo a multidisciplinary assessment, including an evaluation on the patient’s readiness to change his or her opioid use.

Patient education should include a discussion of the risks of methadone (eg, respiratory depression, fatal overdose, and QTc prolongation) and buprenorphine (eg hepatotoxicity) and their benefits (eg, controlling craving, decreasing the risk of relapse). Patients should also be educated about overdose and diversion.

Despite the difficulties inherent in treating patients with opioid use disorder, when used appropriately, opioid agonist therapy can be lifesaving for patients struggling with long-term opioid addiction.

Acknowledgment: We thank Katelyn Colosi, BS, and Drs. Susan Wolfe, Dennis Bouffard, and Sinha Shirshendu for their helpful comments.

For a patient struggling with opioid addiction, opioid agonist therapy with methadone or buprenorphine can reduce craving and opioid use and may even save his or her life. But many clinicians are unfamiliar with this evidence-based treatment,^1,2 which is best started early in the course of addiction.³

See related editorial

This article outlines the pharmacology of these drugs, their clinical uses, and the challenges of using them to treat opioid addiction.

DIAGNOSTIC CRITERIA

Opioid addiction, formally known as opioid use disorder, is a pattern of opioid misuse leading to clinically significant impairment in multiple areas of life. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, lists 11 diagnostic criteria, but only 2 need to be present within the past year to make the diagnosis⁴:

• Taking opioids longer or in higher doses than was intended
• A persistent desire or unsuccessful efforts to cut down or control opioid use
• Spending a great deal of time obtaining, using, or recovering from using opioids
• Craving opioids
• Repeatedly failing to fulfill obligations at work, school, or home due to opioid use
• Continuing to use opioids even though it causes or exacerbates social or interpersonal problems
• Giving up or curtailing important social, occupational, or recreational activities because of opioid use
• Repeatedly using opioids in situations in which it is physically hazardous
• Continuing to use opioids despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the substance
• Tolerance
• Withdrawal.

Recent estimates indicate that 2.23 million people in the United States have opioid use disorder (426,000 with heroin and 1.8 million with prescription opioids).⁵

Progression from prescription opioids to heroin

We have observed that many patients with opioid use disorder start by misusing prescription opioids. Over time, tolerance can develop, which drives patients to use higher and higher doses.⁶

As the addiction progresses, a subset of prescription opioid users advances to using heroin, which is typically less expensive and easier to obtain.⁷ Most patients start with the intranasal route but eventually inject it intravenously.^6,7

For many addicts, heroin use has medical consequences such as hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection, psychiatric problems such as depression and anxiety, and illegal activities such as theft and sex work.⁸ People who use heroin appear to have more severe addiction and a lower socioeconomic status than prescription opioid users.^9–11 But recently, a growing number of middle class individuals are becoming addicted to heroin.¹²

METHADONE

Methadone is a long-acting synthetic opioid that functions as a full agonist on the mu-opioid receptor. The drug binds, occupies, and stimulates the receptor, preventing withdrawal symptoms and reducing opioid cravings for at least 24 hours.¹³

Adverse effects of methadone

The most common adverse effects include lightheadedness, dizziness, sedation, nausea, vomiting, and sweating.¹⁴ Other adverse effects:

Unintentional overdose. The risk is serious, as a single 30-mg dose can be fatal in people who are opioid-naïve.¹³

QTc prolongation, which can lead to torsade de pointes. This risk, which is dose-related, must be taken into consideration in patients who have any cardiac symptoms (eg, syncope, arrhythmia), pathology (familial QT prolongation), or other risk factors for QTc prolongation (eg, hypokalemia, QTc-prolonging medications).¹⁵

Respiratory depression, which can be fatal. This dose-related risk is heightened during the first 4 weeks of treatment if titration is too rapid or if methadone is used in combination with other drugs that cause central nervous system or respiratory depression.^13,14

Starting methadone

To prevent respiratory depression and death related to rapid induction, the general rule is to start methadone at a low daily dose (20–30 mg) depending on the patient’s withdrawal symptoms.¹⁴ During this period, patients need to be closely monitored and educated on the perils of concomitant use of central nervous system depressants.¹⁴

In most patients, the dose is titrated up until their withdrawal symptoms and cravings are eliminated, which generally requires 60 to 120 mg daily.¹⁴ Hepatic and renal impairment, pregnancy, and advanced age can alter methadone pharmacokinetics and may therefore necessitate dose adjustment.

BUPRENORPHINE

Buprenorphine is an alkaloid thebaine opioid derivative that acts as a partial mu-opioid agonist and a kappa antagonist.¹⁶ Like methadone, buprenorphine is used to manage cravings and withdrawal symptoms.¹⁶ Dosages of 4 to 16 mg (up to 32 mg) per day of buprenorphine are usually required to adequately control opioid cravings.¹⁶

Sublingual and subdermal products

Buprenorphine is currently available in the United States in sublingual and subdermal formulations.^16,17

Sublingual buprenorphine is usually combined with naloxone in a 4:1 ratio to deter intravenous use. Intravenous injection of the combination product can precipitate withdrawal due to the antagonist action of naloxone. (Taken orally or sublingually, naloxone is poorly absorbed and has little or no clinical effect.) Buprenorphine-naloxone is available in tablets, a sublingual film strip, and a buccal film strip. Buprenorphine is also available by itself in a sublingual formulation.

The US Food and Drug Administration has approved a buprenorphine subdermal implant, Probuphine. Four rods, about 1 inch long, are placed under the skin in the inner aspect of the upper arm and provide the equivalent of 8 mg of buprenorphine daily for 6 months.¹⁷ However, this method is formulated only for maintenance treatment and cannot be used for induction. Additionally, it is recommended that the implants be surgically removed at the end of 6 months, after which another set of implants can be inserted in the other arm or the patient can switch to sublingual therapy, depending on the clinical situation and patient preference.¹⁷

Generally safer than methadone

Buprenorphine works on the same receptor as methadone and therefore has a similar side effect profile. However, buprenorphine has a ceiling effect, which greatly reduces the risk of fatal respiratory depression.¹⁸ It also does not cause clinically significant QTc prolongation and is preferable in patients who have cardiac risk factors.¹⁸

Another advantage is that buprenorphine has fewer identified medication interactions than methadone.¹⁸ Further, induction of buprenorphine in patients with opioid use disorder has been shown to be safer than methadone.¹⁹

Although buprenorphine has been found to be 6 times safer than methadone with regard to overdose among the general population,²⁰ it can still cause fatal intoxication if used in combination with central nervous system depressants.²¹

Buprenorphine has been also associated with hepatotoxicity, though the risk of new-onset liver disease appears to be low.²²

Besides methadone and buprenorphine, the only other approved option for treating opioid use disorder is the opioid antagonist naltrexone.

Naltrexone has significantly less abuse potential, as it provides no euphoria, but patients do not like it. Even with the long-acting formulation (Vivitrol), naltrexone treatment is significantly less effective than methadone or buprenorphine.^23–25 Further, although naltrexone is not a controlled substance and so does not face the same scrutiny as the agonist therapies, there are other significant barriers. Additional information on naltrexone is presented in reviews by Modesto-Lowe and Van Kirk²⁴ and Woody.²⁵

OBSTACLES TO TREATMENT

People hold conflicting views about opioid agonist therapy. Some believe that “trading one drug for another” is not a legitimate therapeutic strategy, and they may feel ashamed of being on maintenance therapy.²⁶ Similarly, some argue that the answer to establishing stable abstinence does not lie simply in prescribing medications.

The contrary argument is that these medications, if used appropriately, confer many benefits such as reducing the medical and psychosocial sequelae of opioid addiction.¹⁸ In fact, properly treated patients no longer meet the diagnostic criteria of opioid use disorder, and both methadone and buprenorphine are on the World Health Organization’s (WHO) list of essential medicines.²⁷

Despite endorsement by the WHO, the stigma attached to the opioid agonists has been difficult to overcome. Patients with opioid use disorder may be viewed with distrust by healthcare providers and often do not feel welcome in healthcare settings or in self-help recovery groups.²⁸

Barriers to methadone therapy

Federal regulations on methadone prescribing and use were established to promote patient safety and decrease diversion, but they may also complicate access to care.²⁹ They stipulate that to qualify for methadone maintenance, patients need to demonstrate opioid addiction for 1 year, except for pregnant women and those who have been incarcerated in the past 6 months. Patients under the age of 18 must have 2 documented failed treatment episodes as well as approval by a guardian to receive treatment.

Inconvenience. Methadone can be prescribed for opioid dependence only by an accredited treatment program. Patients must therefore travel to the clinic and wait to be evaluated on a daily basis for a minimum of 90 days. Only after they demonstrate consistent responsible behavior and negative results on urine testing do they become eligible to take methadone home.²⁹ If a patient is to travel out of the area during the initial 90 days of treatment, he or she must make arrangements in advance to find a clinic that will provide a “guest dose.”

The inconvenience arising from the regulations may deter some patients from seeking methadone therapy. In spite of this, once patients are started on methadone, more of them continue treatment than with buprenorphine.¹⁸ A proposed reason is that methadone is a potent full opioid agonist and therefore relieves withdrawal symptoms and craving more effectively than buprenorphine, which is a partial agonist.³⁰ Another possible reason is the higher level of supervision afforded by methadone clinics, which require daily contact for at least 90 days. 

Safety concerns arise from methadone diversion, as illicit use may have lethal consequences. In the past decade, deaths from methadone overdose have risen significantly, most of them due to respiratory depression or torsade de pointes.¹³ However, most cases of diversion and overdose involve methadone that is prescribed for pain by individual practitioners and not from maintenance programs.¹³

Advantages of buprenorphine

Together, methadone’s lethality, stigma, and inconvenience may contribute to patients preferring buprenorphine.³¹

The regulations governing buprenorphine’s use are less restrictive than those with methadone. For example, patients must have a diagnosis of opioid addiction to be prescribed buprenorphine, but they are not required to carry the diagnosis for a year before treatment.³¹ Additionally, they do not need to travel to a federally approved opioid treatment center daily and can receive buprenorphine directly from a physician in an outpatient setting.

Under the Drug Abuse Treatment Act (DATA) of 2000, any physician can apply for a waiver to prescribe and dispense buprenorphine in his or her office. To qualify for an initial waiver, physicians must either obtain certification in the fields of addiction medicine or addiction psychiatry or complete an approved 8-hour training session.³² Each physician starts with a maximum of 30 patients, but can apply to treat up to 100 patients after 1 year and eventually up to 275 patients. Physicians must document every buprenorphine prescription they write and be able to refer patients for counseling.³¹

As of February 2017, nurse practitioners and physician assistants can also apply for a DATA 2000 waiver. All waivered providers are subject to unannounced visits from the Drug Enforcement Administration once every 5 years.³²

While there are no federal restrictions on the amount of buprenorphine that can be dispensed, some states and some insurance companies have placed restrictions on dose or length of treatment.³³ Buprenorphine patients can fill their prescriptions at any pharmacy and are permitted to bring their medication home, which improves access to care. However, office-based outpatient treatment is not without risk, and preventing buprenorphine diversion remains a challenge.³⁴

‘Lending’ buprenorphine is a felony

Addicts have illegally used buprenorphine to self-treat opioid withdrawal, craving, and dependence.³⁵ Its misuse has also been coupled with self-treatment of conditions that include depression and pain.³⁶

A survey found that 83.7% of patients deem buprenorphine diversion to be appropriate; further, most patients said they consider it unethical to withhold prescribed buprenorphine from individuals showing symptoms of withdrawal.³⁴ Physicians who prescribe buprenorphine must inform their patients that even “lending” or giving away their medication is a felony.

Prescribing physicians must also be diligent about monitoring for signs of diversion such as inconsistent urine toxicology screens, “lost” medication, and requests for early refills or escalating doses.³⁷

In addition to federal regulations, we propose a 4-step approach to evaluate eligibility for opioid replacement therapy based on existing guidelines.^37–39

Step 1: History and physical examination

The history should give particular attention to the patient’s cardiac, pulmonary, and hepatic status, with consideration of the risks of any medical comorbidities (eg, bacterial endocarditis, HIV and HCV infection) that might influence treatment.³⁷

It is also essential to evaluate for any contraindications or drug interactions before prescribing methadone or buprenorphine.³⁸

Contraindications to methadone maintenance include⁴⁰:

• Cor pulmonale
• Methadone hypersensitivity
• Pseudomembranous colitis
• Selegiline use (due to risk of serotonin syndrome)
• Ileum paralyticus.

Contraindications to buprenorphine use include:

• Hypersensitivity to naloxone or buprenorphine
• Impaired liver function (due to the risk of inadvertent overdose associated with slowed metabolism).

Concurrent use of alcohol or illicit benzodiazepines is a relative contraindication to both methadone and buprenorphine due to the risk of respiratory depression and overdose.³⁷ Likewise, avoid coprescribing opioid agonists and benzodiazepines whenever possible. Obtain a complete list of current medications and query a prescription-monitoring database to determine whether any controlled substances are currently prescribed.³⁷

During the physical examination, look for stigmata of intravenous drug use such as track marks or abscesses³⁷ and document any physical findings consistent with intoxication or withdrawal. Patients must be completely detoxed or in withdrawal before beginning buprenorphine induction; premature induction can precipitate withdrawal.³⁸

A discussion of pregnant patients with opioid use disorder is beyond the scope of this paper. However, it is incumbent on the prescriber to inquire whether the client is pregnant or intends to become pregnant and what birth control methods are in place.

Step 2: Assess psychiatric status

Assessment of the patient’s psychiatric status, including an assessment of alcohol and other drug use, will help determine his or her eligibility for opioid agonists.³⁷ To prepare for the need to manage patients with psychiatrically complex issues, it is helpful to develop relationships with addiction specialists and psychiatrists who are familiar with opioid replacement therapy in your area. This will make it easier to collaborate on patients’ care.

Ask all patients directly about suicidal or homicidal ideation. Any patient with active suicidal or homicidal ideation should be assessed for need of immediate hospitalization by a psychiatrist or another qualified mental health professional. Patients with a history of suicidal ideation should be monitored closely by a mental health professional throughout treatment.³⁷

Many if not most patients with opioid use disorder have concurrent psychiatric disorders, and the interplay between these disorders is complex.^40,41 Depression, for example, can precede and even precipitate drug use (an observation supporting the “self-medication theory”).⁴² If the underlying depressive disorder is not addressed, relapse is nearly inevitable.

It has also been shown that both chronic opioid use and withdrawal can exacerbate aversive emotional states. This escalation of symptoms may result from the pharmacologic effects of opioids or from psychosocial sequelae that can arise from chronic opioid use.⁴¹ In this situation, maintaining abstinence can lead to resolution of depressive symptoms. As depression and opioid use can occur together, successful treatment requires equal attention to both illnesses.

Other common comorbidities in patients with opioid use disorder include posttraumatic stress disorder, attention deficit hyperactivity disorder, antisocial personality disorder, and concurrent substance abuse disorders.⁴³ The confluence of antisocial personality disorder is particularly important, as patients with antisocial personality disorder display disruptive and maladaptive behaviors.

Identify any psychotropic medication that is prescribed and check carefully for drug interactions. This applies especially to methadone, as many psychiatric medications also prolong the QT interval. Moreover, patients may not be forthcoming about the use of psychiatric medication.

Find out whether the patient is using any other addictive substances, particularly those that affect the central nervous system, as those who use fentanyl, benzodiazepines, or alcohol are at the highest risk of overdose.³¹ Often the best option for those with concurrent substance use disorders is inpatient detoxification followed by residential rehabilitation care. Either buprenorphine or methadone can then be initiated upon return to an outpatient setting.

Step 3: Assess psychosocial status

To what extent do the patient’s home environment and support systems promote a drug-free lifestyle? Unfortunately, the psychosocial status of many of these patients is fragile, and they may live in areas where illicit drugs are readily available (which can be urban, suburban, or rural), making it difficult to stay substance-free.³⁸

Generally, lifestyle modifications are needed to transform maladaptive behaviors and promote an environment conducive to long-term recovery. Referrals to social services to address housing, vocational needs, and entitlements may be helpful.³⁹

Step 4: Assess readiness to change

According to one model, people go through 5 stages when changing a behavior: precontemplation, contemplation, preparation for action, action, and maintenance.⁴³ In general, the further along the stages a patient is, the more appropriate he or she is for office-based treatment with buprenorphine.³⁹

The level of change can be assessed with tools such as Stages of Change Readiness and Treatment Eagerness Scale (SOCRATES). Use of stage-specific strategies may enhance a patient’s readiness to cease opioid use.⁴³

Precontemplation. Those in the precontemplation stage are not ready to think about changing their behavior.⁴³ They may be unaware of or unwilling to consider the risks associated with their opioid use and resistant to the idea of quitting. Engagement with opioid agonists for individuals in this stage is low and dropout rates are likely high.

Thus, the proper approach for “precontemplators” is to help them develop some ambivalence about their opioid use. One tactic is to involve the patient in a discussion of the personal benefits and risks of opioid use.

Contemplation. Individuals in the contemplation stage have begun to weigh the costs and benefits of opioid use and express ambivalence about it.⁴⁴ Because the patient is willing to explore the risks of ongoing use and consider the benefits of treatment, the goal in this stage is to elicit a commitment from the individual to seek treatment.

Preparation. The person in this stage moves from thinking about treatment to planning what action to take.⁴⁵ As the individual prepares to enter treatment, indecision tends to resurface, as well as self-doubt about his or her ability to change. During this stage, it is important for the provider to spell out goals (abstinence) and strategies (eg, counseling, medication) and enhance a sense of self-efficacy.

Action and maintenance. Patients in these stages engage in treatment and employ new strategies to abstain from opioid use. Maintaining these behaviors can be a daily struggle. Expressing confidence in the patient’s ability to abstain from use will support his or her progress. Behavioral interventions such as strategic avoidance of triggers and engagement in alternative activities (eg, support groups, exercise, faith-based practices) will help to maintain abstinence.

A CHRONIC CONDITION

Opioid use disorder, like many chronic illnesses, requires long-term attention to attain successful patient outcomes. The opioid agonists methadone and buprenorphine are the mainstay of treatment for it, conferring benefits such as reducing opioid use and preventing relapse.

Candidates for opioid agonist therapy should undergo a multidisciplinary assessment, including an evaluation on the patient’s readiness to change his or her opioid use.

Patient education should include a discussion of the risks of methadone (eg, respiratory depression, fatal overdose, and QTc prolongation) and buprenorphine (eg hepatotoxicity) and their benefits (eg, controlling craving, decreasing the risk of relapse). Patients should also be educated about overdose and diversion.

Despite the difficulties inherent in treating patients with opioid use disorder, when used appropriately, opioid agonist therapy can be lifesaving for patients struggling with long-term opioid addiction.

Acknowledgment: We thank Katelyn Colosi, BS, and Drs. Susan Wolfe, Dennis Bouffard, and Sinha Shirshendu for their helpful comments.

For a patient struggling with opioid addiction, opioid agonist therapy with methadone or buprenorphine can reduce craving and opioid use and may even save his or her life. But many clinicians are unfamiliar with this evidence-based treatment,^1,2 which is best started early in the course of addiction.³

See related editorial

This article outlines the pharmacology of these drugs, their clinical uses, and the challenges of using them to treat opioid addiction.

DIAGNOSTIC CRITERIA

Opioid addiction, formally known as opioid use disorder, is a pattern of opioid misuse leading to clinically significant impairment in multiple areas of life. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, lists 11 diagnostic criteria, but only 2 need to be present within the past year to make the diagnosis⁴:

• Taking opioids longer or in higher doses than was intended
• A persistent desire or unsuccessful efforts to cut down or control opioid use
• Spending a great deal of time obtaining, using, or recovering from using opioids
• Craving opioids
• Repeatedly failing to fulfill obligations at work, school, or home due to opioid use
• Continuing to use opioids even though it causes or exacerbates social or interpersonal problems
• Giving up or curtailing important social, occupational, or recreational activities because of opioid use
• Repeatedly using opioids in situations in which it is physically hazardous
• Continuing to use opioids despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the substance
• Tolerance
• Withdrawal.

Recent estimates indicate that 2.23 million people in the United States have opioid use disorder (426,000 with heroin and 1.8 million with prescription opioids).⁵

Progression from prescription opioids to heroin

We have observed that many patients with opioid use disorder start by misusing prescription opioids. Over time, tolerance can develop, which drives patients to use higher and higher doses.⁶

As the addiction progresses, a subset of prescription opioid users advances to using heroin, which is typically less expensive and easier to obtain.⁷ Most patients start with the intranasal route but eventually inject it intravenously.^6,7

For many addicts, heroin use has medical consequences such as hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection, psychiatric problems such as depression and anxiety, and illegal activities such as theft and sex work.⁸ People who use heroin appear to have more severe addiction and a lower socioeconomic status than prescription opioid users.^9–11 But recently, a growing number of middle class individuals are becoming addicted to heroin.¹²

METHADONE

Methadone is a long-acting synthetic opioid that functions as a full agonist on the mu-opioid receptor. The drug binds, occupies, and stimulates the receptor, preventing withdrawal symptoms and reducing opioid cravings for at least 24 hours.¹³

Adverse effects of methadone

The most common adverse effects include lightheadedness, dizziness, sedation, nausea, vomiting, and sweating.¹⁴ Other adverse effects:

Unintentional overdose. The risk is serious, as a single 30-mg dose can be fatal in people who are opioid-naïve.¹³

QTc prolongation, which can lead to torsade de pointes. This risk, which is dose-related, must be taken into consideration in patients who have any cardiac symptoms (eg, syncope, arrhythmia), pathology (familial QT prolongation), or other risk factors for QTc prolongation (eg, hypokalemia, QTc-prolonging medications).¹⁵

Respiratory depression, which can be fatal. This dose-related risk is heightened during the first 4 weeks of treatment if titration is too rapid or if methadone is used in combination with other drugs that cause central nervous system or respiratory depression.^13,14

Starting methadone

To prevent respiratory depression and death related to rapid induction, the general rule is to start methadone at a low daily dose (20–30 mg) depending on the patient’s withdrawal symptoms.¹⁴ During this period, patients need to be closely monitored and educated on the perils of concomitant use of central nervous system depressants.¹⁴

In most patients, the dose is titrated up until their withdrawal symptoms and cravings are eliminated, which generally requires 60 to 120 mg daily.¹⁴ Hepatic and renal impairment, pregnancy, and advanced age can alter methadone pharmacokinetics and may therefore necessitate dose adjustment.

BUPRENORPHINE

Buprenorphine is an alkaloid thebaine opioid derivative that acts as a partial mu-opioid agonist and a kappa antagonist.¹⁶ Like methadone, buprenorphine is used to manage cravings and withdrawal symptoms.¹⁶ Dosages of 4 to 16 mg (up to 32 mg) per day of buprenorphine are usually required to adequately control opioid cravings.¹⁶

Sublingual and subdermal products

Buprenorphine is currently available in the United States in sublingual and subdermal formulations.^16,17

Sublingual buprenorphine is usually combined with naloxone in a 4:1 ratio to deter intravenous use. Intravenous injection of the combination product can precipitate withdrawal due to the antagonist action of naloxone. (Taken orally or sublingually, naloxone is poorly absorbed and has little or no clinical effect.) Buprenorphine-naloxone is available in tablets, a sublingual film strip, and a buccal film strip. Buprenorphine is also available by itself in a sublingual formulation.

The US Food and Drug Administration has approved a buprenorphine subdermal implant, Probuphine. Four rods, about 1 inch long, are placed under the skin in the inner aspect of the upper arm and provide the equivalent of 8 mg of buprenorphine daily for 6 months.¹⁷ However, this method is formulated only for maintenance treatment and cannot be used for induction. Additionally, it is recommended that the implants be surgically removed at the end of 6 months, after which another set of implants can be inserted in the other arm or the patient can switch to sublingual therapy, depending on the clinical situation and patient preference.¹⁷

Generally safer than methadone

Buprenorphine works on the same receptor as methadone and therefore has a similar side effect profile. However, buprenorphine has a ceiling effect, which greatly reduces the risk of fatal respiratory depression.¹⁸ It also does not cause clinically significant QTc prolongation and is preferable in patients who have cardiac risk factors.¹⁸

Another advantage is that buprenorphine has fewer identified medication interactions than methadone.¹⁸ Further, induction of buprenorphine in patients with opioid use disorder has been shown to be safer than methadone.¹⁹

Although buprenorphine has been found to be 6 times safer than methadone with regard to overdose among the general population,²⁰ it can still cause fatal intoxication if used in combination with central nervous system depressants.²¹

Buprenorphine has been also associated with hepatotoxicity, though the risk of new-onset liver disease appears to be low.²²

Besides methadone and buprenorphine, the only other approved option for treating opioid use disorder is the opioid antagonist naltrexone.

Naltrexone has significantly less abuse potential, as it provides no euphoria, but patients do not like it. Even with the long-acting formulation (Vivitrol), naltrexone treatment is significantly less effective than methadone or buprenorphine.^23–25 Further, although naltrexone is not a controlled substance and so does not face the same scrutiny as the agonist therapies, there are other significant barriers. Additional information on naltrexone is presented in reviews by Modesto-Lowe and Van Kirk²⁴ and Woody.²⁵

OBSTACLES TO TREATMENT

People hold conflicting views about opioid agonist therapy. Some believe that “trading one drug for another” is not a legitimate therapeutic strategy, and they may feel ashamed of being on maintenance therapy.²⁶ Similarly, some argue that the answer to establishing stable abstinence does not lie simply in prescribing medications.

The contrary argument is that these medications, if used appropriately, confer many benefits such as reducing the medical and psychosocial sequelae of opioid addiction.¹⁸ In fact, properly treated patients no longer meet the diagnostic criteria of opioid use disorder, and both methadone and buprenorphine are on the World Health Organization’s (WHO) list of essential medicines.²⁷

Despite endorsement by the WHO, the stigma attached to the opioid agonists has been difficult to overcome. Patients with opioid use disorder may be viewed with distrust by healthcare providers and often do not feel welcome in healthcare settings or in self-help recovery groups.²⁸

Barriers to methadone therapy

Federal regulations on methadone prescribing and use were established to promote patient safety and decrease diversion, but they may also complicate access to care.²⁹ They stipulate that to qualify for methadone maintenance, patients need to demonstrate opioid addiction for 1 year, except for pregnant women and those who have been incarcerated in the past 6 months. Patients under the age of 18 must have 2 documented failed treatment episodes as well as approval by a guardian to receive treatment.

Inconvenience. Methadone can be prescribed for opioid dependence only by an accredited treatment program. Patients must therefore travel to the clinic and wait to be evaluated on a daily basis for a minimum of 90 days. Only after they demonstrate consistent responsible behavior and negative results on urine testing do they become eligible to take methadone home.²⁹ If a patient is to travel out of the area during the initial 90 days of treatment, he or she must make arrangements in advance to find a clinic that will provide a “guest dose.”

The inconvenience arising from the regulations may deter some patients from seeking methadone therapy. In spite of this, once patients are started on methadone, more of them continue treatment than with buprenorphine.¹⁸ A proposed reason is that methadone is a potent full opioid agonist and therefore relieves withdrawal symptoms and craving more effectively than buprenorphine, which is a partial agonist.³⁰ Another possible reason is the higher level of supervision afforded by methadone clinics, which require daily contact for at least 90 days. 

Safety concerns arise from methadone diversion, as illicit use may have lethal consequences. In the past decade, deaths from methadone overdose have risen significantly, most of them due to respiratory depression or torsade de pointes.¹³ However, most cases of diversion and overdose involve methadone that is prescribed for pain by individual practitioners and not from maintenance programs.¹³

Advantages of buprenorphine

Together, methadone’s lethality, stigma, and inconvenience may contribute to patients preferring buprenorphine.³¹

The regulations governing buprenorphine’s use are less restrictive than those with methadone. For example, patients must have a diagnosis of opioid addiction to be prescribed buprenorphine, but they are not required to carry the diagnosis for a year before treatment.³¹ Additionally, they do not need to travel to a federally approved opioid treatment center daily and can receive buprenorphine directly from a physician in an outpatient setting.

Under the Drug Abuse Treatment Act (DATA) of 2000, any physician can apply for a waiver to prescribe and dispense buprenorphine in his or her office. To qualify for an initial waiver, physicians must either obtain certification in the fields of addiction medicine or addiction psychiatry or complete an approved 8-hour training session.³² Each physician starts with a maximum of 30 patients, but can apply to treat up to 100 patients after 1 year and eventually up to 275 patients. Physicians must document every buprenorphine prescription they write and be able to refer patients for counseling.³¹

As of February 2017, nurse practitioners and physician assistants can also apply for a DATA 2000 waiver. All waivered providers are subject to unannounced visits from the Drug Enforcement Administration once every 5 years.³²

While there are no federal restrictions on the amount of buprenorphine that can be dispensed, some states and some insurance companies have placed restrictions on dose or length of treatment.³³ Buprenorphine patients can fill their prescriptions at any pharmacy and are permitted to bring their medication home, which improves access to care. However, office-based outpatient treatment is not without risk, and preventing buprenorphine diversion remains a challenge.³⁴

‘Lending’ buprenorphine is a felony

Addicts have illegally used buprenorphine to self-treat opioid withdrawal, craving, and dependence.³⁵ Its misuse has also been coupled with self-treatment of conditions that include depression and pain.³⁶

A survey found that 83.7% of patients deem buprenorphine diversion to be appropriate; further, most patients said they consider it unethical to withhold prescribed buprenorphine from individuals showing symptoms of withdrawal.³⁴ Physicians who prescribe buprenorphine must inform their patients that even “lending” or giving away their medication is a felony.

Prescribing physicians must also be diligent about monitoring for signs of diversion such as inconsistent urine toxicology screens, “lost” medication, and requests for early refills or escalating doses.³⁷

In addition to federal regulations, we propose a 4-step approach to evaluate eligibility for opioid replacement therapy based on existing guidelines.^37–39

Step 1: History and physical examination

The history should give particular attention to the patient’s cardiac, pulmonary, and hepatic status, with consideration of the risks of any medical comorbidities (eg, bacterial endocarditis, HIV and HCV infection) that might influence treatment.³⁷

It is also essential to evaluate for any contraindications or drug interactions before prescribing methadone or buprenorphine.³⁸

Contraindications to methadone maintenance include⁴⁰:

• Cor pulmonale
• Methadone hypersensitivity
• Pseudomembranous colitis
• Selegiline use (due to risk of serotonin syndrome)
• Ileum paralyticus.

Contraindications to buprenorphine use include:

• Hypersensitivity to naloxone or buprenorphine
• Impaired liver function (due to the risk of inadvertent overdose associated with slowed metabolism).

Concurrent use of alcohol or illicit benzodiazepines is a relative contraindication to both methadone and buprenorphine due to the risk of respiratory depression and overdose.³⁷ Likewise, avoid coprescribing opioid agonists and benzodiazepines whenever possible. Obtain a complete list of current medications and query a prescription-monitoring database to determine whether any controlled substances are currently prescribed.³⁷

During the physical examination, look for stigmata of intravenous drug use such as track marks or abscesses³⁷ and document any physical findings consistent with intoxication or withdrawal. Patients must be completely detoxed or in withdrawal before beginning buprenorphine induction; premature induction can precipitate withdrawal.³⁸

A discussion of pregnant patients with opioid use disorder is beyond the scope of this paper. However, it is incumbent on the prescriber to inquire whether the client is pregnant or intends to become pregnant and what birth control methods are in place.

Step 2: Assess psychiatric status

Assessment of the patient’s psychiatric status, including an assessment of alcohol and other drug use, will help determine his or her eligibility for opioid agonists.³⁷ To prepare for the need to manage patients with psychiatrically complex issues, it is helpful to develop relationships with addiction specialists and psychiatrists who are familiar with opioid replacement therapy in your area. This will make it easier to collaborate on patients’ care.

Ask all patients directly about suicidal or homicidal ideation. Any patient with active suicidal or homicidal ideation should be assessed for need of immediate hospitalization by a psychiatrist or another qualified mental health professional. Patients with a history of suicidal ideation should be monitored closely by a mental health professional throughout treatment.³⁷

Many if not most patients with opioid use disorder have concurrent psychiatric disorders, and the interplay between these disorders is complex.^40,41 Depression, for example, can precede and even precipitate drug use (an observation supporting the “self-medication theory”).⁴² If the underlying depressive disorder is not addressed, relapse is nearly inevitable.

It has also been shown that both chronic opioid use and withdrawal can exacerbate aversive emotional states. This escalation of symptoms may result from the pharmacologic effects of opioids or from psychosocial sequelae that can arise from chronic opioid use.⁴¹ In this situation, maintaining abstinence can lead to resolution of depressive symptoms. As depression and opioid use can occur together, successful treatment requires equal attention to both illnesses.

Other common comorbidities in patients with opioid use disorder include posttraumatic stress disorder, attention deficit hyperactivity disorder, antisocial personality disorder, and concurrent substance abuse disorders.⁴³ The confluence of antisocial personality disorder is particularly important, as patients with antisocial personality disorder display disruptive and maladaptive behaviors.

Identify any psychotropic medication that is prescribed and check carefully for drug interactions. This applies especially to methadone, as many psychiatric medications also prolong the QT interval. Moreover, patients may not be forthcoming about the use of psychiatric medication.

Find out whether the patient is using any other addictive substances, particularly those that affect the central nervous system, as those who use fentanyl, benzodiazepines, or alcohol are at the highest risk of overdose.³¹ Often the best option for those with concurrent substance use disorders is inpatient detoxification followed by residential rehabilitation care. Either buprenorphine or methadone can then be initiated upon return to an outpatient setting.

Step 3: Assess psychosocial status

To what extent do the patient’s home environment and support systems promote a drug-free lifestyle? Unfortunately, the psychosocial status of many of these patients is fragile, and they may live in areas where illicit drugs are readily available (which can be urban, suburban, or rural), making it difficult to stay substance-free.³⁸

Generally, lifestyle modifications are needed to transform maladaptive behaviors and promote an environment conducive to long-term recovery. Referrals to social services to address housing, vocational needs, and entitlements may be helpful.³⁹

Step 4: Assess readiness to change

According to one model, people go through 5 stages when changing a behavior: precontemplation, contemplation, preparation for action, action, and maintenance.⁴³ In general, the further along the stages a patient is, the more appropriate he or she is for office-based treatment with buprenorphine.³⁹

The level of change can be assessed with tools such as Stages of Change Readiness and Treatment Eagerness Scale (SOCRATES). Use of stage-specific strategies may enhance a patient’s readiness to cease opioid use.⁴³

Precontemplation. Those in the precontemplation stage are not ready to think about changing their behavior.⁴³ They may be unaware of or unwilling to consider the risks associated with their opioid use and resistant to the idea of quitting. Engagement with opioid agonists for individuals in this stage is low and dropout rates are likely high.

Thus, the proper approach for “precontemplators” is to help them develop some ambivalence about their opioid use. One tactic is to involve the patient in a discussion of the personal benefits and risks of opioid use.

Contemplation. Individuals in the contemplation stage have begun to weigh the costs and benefits of opioid use and express ambivalence about it.⁴⁴ Because the patient is willing to explore the risks of ongoing use and consider the benefits of treatment, the goal in this stage is to elicit a commitment from the individual to seek treatment.

Preparation. The person in this stage moves from thinking about treatment to planning what action to take.⁴⁵ As the individual prepares to enter treatment, indecision tends to resurface, as well as self-doubt about his or her ability to change. During this stage, it is important for the provider to spell out goals (abstinence) and strategies (eg, counseling, medication) and enhance a sense of self-efficacy.

Action and maintenance. Patients in these stages engage in treatment and employ new strategies to abstain from opioid use. Maintaining these behaviors can be a daily struggle. Expressing confidence in the patient’s ability to abstain from use will support his or her progress. Behavioral interventions such as strategic avoidance of triggers and engagement in alternative activities (eg, support groups, exercise, faith-based practices) will help to maintain abstinence.

A CHRONIC CONDITION