American Society of Nuclear Cardiology (ASNC): Annual Scientific Session

DENVER – A cascade of data generated recently by the CONFIRM registry is turning heads and winning converts to coronary CT angiography as a reasonable first-line test to diagnose or exclude coronary artery disease in many symptomatic patients with no history of the disease.

"The CONFIRM information about the need to rethink people’s pretest likelihood of CAD is enormously important. It shows that if we think a patient’s likelihood is intermediate, it’s actually low. So CT angiography might be the least expensive way to exclude CAD," Dr. James E. Udelson observed during a panel discussion at the annual meeting of the American Society of Nuclear Cardiology.

In addition to being less expensive than SPECT (single-photon emission CT) myocardial perfusion imaging for this purpose, CTA also confers less radiation exposure, which is a particularly important consideration given that that the majority of patients undergoing evaluation for symptoms suggestive of CAD turn out not to have it, added Dr. Udelson, chief of cardiology and director of the nuclear cardiology laboratory at Tufts Medical Center, Boston.

Dr. Udelson is not a CT angiographer and is not involved with CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter Registry). Neither is fellow panelist Dr. John J. Mahmarian. But he too finds CONFIRM compelling.

"I’m really intrigued by the CONFIRM data on nonobstructive plaque. These individuals with nonobstructive atherosclerotic plaque have a good short-term risk but may not have a good long-term risk. With the armamentarium we have today, it’s important to know that so we can treat people more aggressively and impact the disease process," said Dr. Mahmarian, ASNC president-elect and director of nuclear cardiology and CT services at the Methodist DeBakey Heart and Vascular Institute, Houston.

Their comments came in reaction to a wide-ranging update on the registry by CONFIRM investigator Dr. James K. Min of Cedars-Sinai Medical Center in Los Angeles.

Dr. Min explained that CONFIRM is a prospective, multinational registry including more than 32,000 consecutive patients who have undergone CTA at 18 participating sites. The registry was created to answer three questions of fundamental importance regarding the noninvasive imaging procedure: Does it have the ability to diagnose or exclude CAD as well as does invasive coronary angiography? Does it reduce the need for percutaneous angiography? And does it improve health outcomes for patients with acute chest pain who present to emergency departments and other settings?

The answer on all three counts is ‘yes,’ although some of the data are preliminary, Dr. Min said. The registry is being expanded, with follow-up to be extended to a median of 5 years, along with the possible addition of another 12,000-15,000 patients in order to strengthen the findings.

The power of CTA as a risk stratification tool was highlighted in a recent CONFIRM publication (J. Am. Coll. Cardiol. 2011;58:849-60). Dr. Min and his coworkers reported on nearly 24,000 consecutive patients without known pretest CAD who were prospectively followed for a mean of 2.3 years after undergoing CTA for assessment of suspected CAD. These were mainly middle-aged patients with a high prevalence of cardiovascular risk factors. In all, 71% had an intermediate or high pretest likelihood of obstructive CAD.

In this study population, a normal CTA study (found in 43% of patients) was associated with a highly favorable prognosis – namely, an all-cause mortality rate of just 0.28% per year. Moreover, a normal CTA result carried a 4-year "warranty."

Another key finding was that nonobstructive CAD (that is, a 1%-49% stenosis) was associated with a 1.6-fold increased risk of mortality in a multivariate risk-adjusted analysis. Nonobstructive CAD was detected in 34% of subjects.

Mortality risk climbed stepwise with the number of coronary vessels showing obstructive CAD on CTA: a doubling of risk in patients with single-vessel obstructive disease relative to the risk in those with a normal study; a 2.92-fold increased risk in those with two-vessel obstructive CAD; and a 3.7-fold increased risk in patients with triple-vessel or left anterior descending obstructive disease.

The mortality risk associated with obstructive CAD varied by age and sex. Patients younger than age 65 had a significantly greater mortality risk for two-vessel disease than did those aged 65 years or older. The younger patients with two-vessel obstructive disease had a fourfold greater death rate than did young patients with a normal CTA study, whereas older patients with double-vessel disease had a 2.46-fold increased risk. Similarly, triple-vessel obstructive disease in patients younger than age 65 was associated with a 6.2-fold increased risk of death, compared with those who had a normal CTA, a risk twice that conferred by three-vessel obstructive disease in older patients.

The relative hazards for single- and double-vessel obstructive CAD were not significantly different for men vs. women. However, women with three-vessel disease had a 4.2-fold increased mortality risk, significantly greater than the 3.3-fold risk associated with triple-vessel disease in men.

In another CONFIRM analysis, this one involving roughly 8,100 patients with an average pretest likelihood of obstructive CAD of 50% by the widely used Diamond Forrester clinical risk score, investigators found that the actual prevalence of obstructive CAD on CTA was only 18%. The take-home lesson here is that cardiologists severely overestimate the likelihood of significant disease when they rely on clinical risk scores that were developed in an earlier era, Dr. Min emphasized.

Another CONFIRM analysis involved 15,223 patients, 7.2% of whom underwent coronary revascularization following CTA. Among the subgroup with high-risk CAD as defined by the Duke severity categorization criteria – for example, three vessels having moderate stenoses or two with severe stenoses – the mortality rate during an average 2.3 years of follow-up was 2.3% in those who were revascularized, significantly better than the 5.3% rate with medical management.

Thus, it appears that using CTA to identify patients with high-risk CAD results in a therapeutic benefit when such patients undergo revascularization, according to Dr. Min. In contrast, in patients with CTA findings indicative of non–high-risk CAD, mortality rates weren’t significantly different between those who had revascularization and those who had medical management only.

CONFIRM has also showed that CTA reduces the need for invasive coronary angiography. Patients with a normal CTA had a 3-year rate of invasive coronary angiography of 2.5%, and a 0.3% revascularization rate. These rates rose in graded fashion to a 44% invasive angiography rate and a 28% revascularization rate in patients with obstructive single-vessel disease on CTA; a 53% invasive coronary angiography rate and 44% revascularization for those identified as having obstructive two-vessel disease; and a 69% coronary angiography rate and 67% revascularization among patients found on CTA to have obstructive three-vessel or left anterior descending disease.

Dr. Min said that at present there is no evidence-based role for CTA in the evaluation of patients without chest pain or other symptoms suggestive of CAD. And there are better prognostic tests for those with known CAD, he added.

"I must say, looking at it from the outside, it’s really breathtaking how fast the data have grown over the last few years for CT angiography," Dr. Udelson commented. "You in the CT world have, in just a few short years, developed enormous databases it took those of us in nuclear imaging much longer to develop, and you can look at things nuclear can’t, like nonobstructive plaque, where the outcome is different than in people with normal coronary arteries."

Dr. Min has received research grants and is on the speakers bureau for GE Healthcare.

DENVER – A cascade of data generated recently by the CONFIRM registry is turning heads and winning converts to coronary CT angiography as a reasonable first-line test to diagnose or exclude coronary artery disease in many symptomatic patients with no history of the disease.

"The CONFIRM information about the need to rethink people’s pretest likelihood of CAD is enormously important. It shows that if we think a patient’s likelihood is intermediate, it’s actually low. So CT angiography might be the least expensive way to exclude CAD," Dr. James E. Udelson observed during a panel discussion at the annual meeting of the American Society of Nuclear Cardiology.

In addition to being less expensive than SPECT (single-photon emission CT) myocardial perfusion imaging for this purpose, CTA also confers less radiation exposure, which is a particularly important consideration given that that the majority of patients undergoing evaluation for symptoms suggestive of CAD turn out not to have it, added Dr. Udelson, chief of cardiology and director of the nuclear cardiology laboratory at Tufts Medical Center, Boston.

Dr. Udelson is not a CT angiographer and is not involved with CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter Registry). Neither is fellow panelist Dr. John J. Mahmarian. But he too finds CONFIRM compelling.

"I’m really intrigued by the CONFIRM data on nonobstructive plaque. These individuals with nonobstructive atherosclerotic plaque have a good short-term risk but may not have a good long-term risk. With the armamentarium we have today, it’s important to know that so we can treat people more aggressively and impact the disease process," said Dr. Mahmarian, ASNC president-elect and director of nuclear cardiology and CT services at the Methodist DeBakey Heart and Vascular Institute, Houston.

Their comments came in reaction to a wide-ranging update on the registry by CONFIRM investigator Dr. James K. Min of Cedars-Sinai Medical Center in Los Angeles.

Dr. Min explained that CONFIRM is a prospective, multinational registry including more than 32,000 consecutive patients who have undergone CTA at 18 participating sites. The registry was created to answer three questions of fundamental importance regarding the noninvasive imaging procedure: Does it have the ability to diagnose or exclude CAD as well as does invasive coronary angiography? Does it reduce the need for percutaneous angiography? And does it improve health outcomes for patients with acute chest pain who present to emergency departments and other settings?

The answer on all three counts is ‘yes,’ although some of the data are preliminary, Dr. Min said. The registry is being expanded, with follow-up to be extended to a median of 5 years, along with the possible addition of another 12,000-15,000 patients in order to strengthen the findings.

The power of CTA as a risk stratification tool was highlighted in a recent CONFIRM publication (J. Am. Coll. Cardiol. 2011;58:849-60). Dr. Min and his coworkers reported on nearly 24,000 consecutive patients without known pretest CAD who were prospectively followed for a mean of 2.3 years after undergoing CTA for assessment of suspected CAD. These were mainly middle-aged patients with a high prevalence of cardiovascular risk factors. In all, 71% had an intermediate or high pretest likelihood of obstructive CAD.

In this study population, a normal CTA study (found in 43% of patients) was associated with a highly favorable prognosis – namely, an all-cause mortality rate of just 0.28% per year. Moreover, a normal CTA result carried a 4-year "warranty."

Another key finding was that nonobstructive CAD (that is, a 1%-49% stenosis) was associated with a 1.6-fold increased risk of mortality in a multivariate risk-adjusted analysis. Nonobstructive CAD was detected in 34% of subjects.

Mortality risk climbed stepwise with the number of coronary vessels showing obstructive CAD on CTA: a doubling of risk in patients with single-vessel obstructive disease relative to the risk in those with a normal study; a 2.92-fold increased risk in those with two-vessel obstructive CAD; and a 3.7-fold increased risk in patients with triple-vessel or left anterior descending obstructive disease.

The mortality risk associated with obstructive CAD varied by age and sex. Patients younger than age 65 had a significantly greater mortality risk for two-vessel disease than did those aged 65 years or older. The younger patients with two-vessel obstructive disease had a fourfold greater death rate than did young patients with a normal CTA study, whereas older patients with double-vessel disease had a 2.46-fold increased risk. Similarly, triple-vessel obstructive disease in patients younger than age 65 was associated with a 6.2-fold increased risk of death, compared with those who had a normal CTA, a risk twice that conferred by three-vessel obstructive disease in older patients.

The relative hazards for single- and double-vessel obstructive CAD were not significantly different for men vs. women. However, women with three-vessel disease had a 4.2-fold increased mortality risk, significantly greater than the 3.3-fold risk associated with triple-vessel disease in men.

In another CONFIRM analysis, this one involving roughly 8,100 patients with an average pretest likelihood of obstructive CAD of 50% by the widely used Diamond Forrester clinical risk score, investigators found that the actual prevalence of obstructive CAD on CTA was only 18%. The take-home lesson here is that cardiologists severely overestimate the likelihood of significant disease when they rely on clinical risk scores that were developed in an earlier era, Dr. Min emphasized.

Another CONFIRM analysis involved 15,223 patients, 7.2% of whom underwent coronary revascularization following CTA. Among the subgroup with high-risk CAD as defined by the Duke severity categorization criteria – for example, three vessels having moderate stenoses or two with severe stenoses – the mortality rate during an average 2.3 years of follow-up was 2.3% in those who were revascularized, significantly better than the 5.3% rate with medical management.

Thus, it appears that using CTA to identify patients with high-risk CAD results in a therapeutic benefit when such patients undergo revascularization, according to Dr. Min. In contrast, in patients with CTA findings indicative of non–high-risk CAD, mortality rates weren’t significantly different between those who had revascularization and those who had medical management only.

CONFIRM has also showed that CTA reduces the need for invasive coronary angiography. Patients with a normal CTA had a 3-year rate of invasive coronary angiography of 2.5%, and a 0.3% revascularization rate. These rates rose in graded fashion to a 44% invasive angiography rate and a 28% revascularization rate in patients with obstructive single-vessel disease on CTA; a 53% invasive coronary angiography rate and 44% revascularization for those identified as having obstructive two-vessel disease; and a 69% coronary angiography rate and 67% revascularization among patients found on CTA to have obstructive three-vessel or left anterior descending disease.

Dr. Min said that at present there is no evidence-based role for CTA in the evaluation of patients without chest pain or other symptoms suggestive of CAD. And there are better prognostic tests for those with known CAD, he added.

"I must say, looking at it from the outside, it’s really breathtaking how fast the data have grown over the last few years for CT angiography," Dr. Udelson commented. "You in the CT world have, in just a few short years, developed enormous databases it took those of us in nuclear imaging much longer to develop, and you can look at things nuclear can’t, like nonobstructive plaque, where the outcome is different than in people with normal coronary arteries."

Dr. Min has received research grants and is on the speakers bureau for GE Healthcare.

DENVER – A cascade of data generated recently by the CONFIRM registry is turning heads and winning converts to coronary CT angiography as a reasonable first-line test to diagnose or exclude coronary artery disease in many symptomatic patients with no history of the disease.

"The CONFIRM information about the need to rethink people’s pretest likelihood of CAD is enormously important. It shows that if we think a patient’s likelihood is intermediate, it’s actually low. So CT angiography might be the least expensive way to exclude CAD," Dr. James E. Udelson observed during a panel discussion at the annual meeting of the American Society of Nuclear Cardiology.

In addition to being less expensive than SPECT (single-photon emission CT) myocardial perfusion imaging for this purpose, CTA also confers less radiation exposure, which is a particularly important consideration given that that the majority of patients undergoing evaluation for symptoms suggestive of CAD turn out not to have it, added Dr. Udelson, chief of cardiology and director of the nuclear cardiology laboratory at Tufts Medical Center, Boston.

Dr. Udelson is not a CT angiographer and is not involved with CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter Registry). Neither is fellow panelist Dr. John J. Mahmarian. But he too finds CONFIRM compelling.

"I’m really intrigued by the CONFIRM data on nonobstructive plaque. These individuals with nonobstructive atherosclerotic plaque have a good short-term risk but may not have a good long-term risk. With the armamentarium we have today, it’s important to know that so we can treat people more aggressively and impact the disease process," said Dr. Mahmarian, ASNC president-elect and director of nuclear cardiology and CT services at the Methodist DeBakey Heart and Vascular Institute, Houston.

Their comments came in reaction to a wide-ranging update on the registry by CONFIRM investigator Dr. James K. Min of Cedars-Sinai Medical Center in Los Angeles.

Dr. Min explained that CONFIRM is a prospective, multinational registry including more than 32,000 consecutive patients who have undergone CTA at 18 participating sites. The registry was created to answer three questions of fundamental importance regarding the noninvasive imaging procedure: Does it have the ability to diagnose or exclude CAD as well as does invasive coronary angiography? Does it reduce the need for percutaneous angiography? And does it improve health outcomes for patients with acute chest pain who present to emergency departments and other settings?

The answer on all three counts is ‘yes,’ although some of the data are preliminary, Dr. Min said. The registry is being expanded, with follow-up to be extended to a median of 5 years, along with the possible addition of another 12,000-15,000 patients in order to strengthen the findings.

The power of CTA as a risk stratification tool was highlighted in a recent CONFIRM publication (J. Am. Coll. Cardiol. 2011;58:849-60). Dr. Min and his coworkers reported on nearly 24,000 consecutive patients without known pretest CAD who were prospectively followed for a mean of 2.3 years after undergoing CTA for assessment of suspected CAD. These were mainly middle-aged patients with a high prevalence of cardiovascular risk factors. In all, 71% had an intermediate or high pretest likelihood of obstructive CAD.

In this study population, a normal CTA study (found in 43% of patients) was associated with a highly favorable prognosis – namely, an all-cause mortality rate of just 0.28% per year. Moreover, a normal CTA result carried a 4-year "warranty."

Another key finding was that nonobstructive CAD (that is, a 1%-49% stenosis) was associated with a 1.6-fold increased risk of mortality in a multivariate risk-adjusted analysis. Nonobstructive CAD was detected in 34% of subjects.

Mortality risk climbed stepwise with the number of coronary vessels showing obstructive CAD on CTA: a doubling of risk in patients with single-vessel obstructive disease relative to the risk in those with a normal study; a 2.92-fold increased risk in those with two-vessel obstructive CAD; and a 3.7-fold increased risk in patients with triple-vessel or left anterior descending obstructive disease.

The mortality risk associated with obstructive CAD varied by age and sex. Patients younger than age 65 had a significantly greater mortality risk for two-vessel disease than did those aged 65 years or older. The younger patients with two-vessel obstructive disease had a fourfold greater death rate than did young patients with a normal CTA study, whereas older patients with double-vessel disease had a 2.46-fold increased risk. Similarly, triple-vessel obstructive disease in patients younger than age 65 was associated with a 6.2-fold increased risk of death, compared with those who had a normal CTA, a risk twice that conferred by three-vessel obstructive disease in older patients.

The relative hazards for single- and double-vessel obstructive CAD were not significantly different for men vs. women. However, women with three-vessel disease had a 4.2-fold increased mortality risk, significantly greater than the 3.3-fold risk associated with triple-vessel disease in men.

In another CONFIRM analysis, this one involving roughly 8,100 patients with an average pretest likelihood of obstructive CAD of 50% by the widely used Diamond Forrester clinical risk score, investigators found that the actual prevalence of obstructive CAD on CTA was only 18%. The take-home lesson here is that cardiologists severely overestimate the likelihood of significant disease when they rely on clinical risk scores that were developed in an earlier era, Dr. Min emphasized.

Another CONFIRM analysis involved 15,223 patients, 7.2% of whom underwent coronary revascularization following CTA. Among the subgroup with high-risk CAD as defined by the Duke severity categorization criteria – for example, three vessels having moderate stenoses or two with severe stenoses – the mortality rate during an average 2.3 years of follow-up was 2.3% in those who were revascularized, significantly better than the 5.3% rate with medical management.

Thus, it appears that using CTA to identify patients with high-risk CAD results in a therapeutic benefit when such patients undergo revascularization, according to Dr. Min. In contrast, in patients with CTA findings indicative of non–high-risk CAD, mortality rates weren’t significantly different between those who had revascularization and those who had medical management only.

CONFIRM has also showed that CTA reduces the need for invasive coronary angiography. Patients with a normal CTA had a 3-year rate of invasive coronary angiography of 2.5%, and a 0.3% revascularization rate. These rates rose in graded fashion to a 44% invasive angiography rate and a 28% revascularization rate in patients with obstructive single-vessel disease on CTA; a 53% invasive coronary angiography rate and 44% revascularization for those identified as having obstructive two-vessel disease; and a 69% coronary angiography rate and 67% revascularization among patients found on CTA to have obstructive three-vessel or left anterior descending disease.

Dr. Min said that at present there is no evidence-based role for CTA in the evaluation of patients without chest pain or other symptoms suggestive of CAD. And there are better prognostic tests for those with known CAD, he added.

"I must say, looking at it from the outside, it’s really breathtaking how fast the data have grown over the last few years for CT angiography," Dr. Udelson commented. "You in the CT world have, in just a few short years, developed enormous databases it took those of us in nuclear imaging much longer to develop, and you can look at things nuclear can’t, like nonobstructive plaque, where the outcome is different than in people with normal coronary arteries."

Dr. Min has received research grants and is on the speakers bureau for GE Healthcare.

DENVER – The historically shaky evidence base for cardiac imaging strategies is in the midst of being shored up by a strong new foundation.

Just a couple of years ago, analysts concluded that cardiac imaging guidelines have among the weakest supporting evidence bases of any of the 53 American College of Cardiology/American Heart Association practice guidelines they looked at. The investigators found that only 2.4% of the evidence supporting the imaging guidelines had a level of evidence of A, meaning supported by multiple randomized trials. Thirty-seven percent of the evidence was level B, coming from multiple observational studies. Another 17% was based on expert opinion, and the rest of the imaging guideline recommendations were not supported by any conclusive evidence (JAMA 2009;301:831-41).

All that is clearly in the process of changing, and in a big way, Dr. James E. Udelson observed at the annual meeting of the American Society of Nuclear Cardiology.

An unprecedented raft of multicenter randomized trials is underway in patients with chest pain. The government-supported studies range in size from 4,300 to 10,000 patients. They are variously aimed at determining whether anatomic imaging via coronary CT angiography (CTA) or functional imaging by SPECT myocardial perfusion imaging stress ECG, or stress echocardiography is the best initial strategy for the diagnosis of coronary artery disease, and at using imaging results to identify optimal management strategies, explained Dr. Udelson, chief of cardiology and director of the nuclear cardiology laboratory at Tufts Medical Center, Boston.

Here’s what’s underway:

• PROMISE. The PROspective Multicenter Imaging Study for Evaluation of chest pain), funded by the National Heart, Lung, and Blood Institute, involves 10,000 patients with symptoms suggestive of CAD and low to intermediate pretest probability of CAD. They’ll be randomized to CTA or functional imaging by SPECT myocardial perfusion imaging, stress ECG, or stress echo, with the study results immediately available to the care team for use in management decisions.

The primary end point is the 30-month composite of death, MI, major complications due to cardiac catheterization, or hospitalization for unstable angina. The study hypothesis is that noninvasive anatomic imaging via CTA will result in superior long-term outcomes.

Enrollment is progressing quickly, with 2,800 randomized patients, according to Dr. Udelson, who is a PROMISE investigator.

• RESCUE. In the Randomized Evaluation of patients with Stable angina Comparing Utilization of diagnostic Examinations, 4,300 symptomatic outpatients are being randomized to SPECT myocardial perfusion imaging or CTA, with their subsequent management being driven by an algorithm based on their test results. The hypothesis here is that CTA will be associated with no increase in adverse events, similar outcomes, lower cost, less radiation exposure, and resultant superior cost-effectiveness. Dr. Udelson is an investigator in RESCUE, which is supported by the Agency for Healthcare Research and Quality and the American College of Radiology Imaging Network.

• ISCHEMIA. The most ambitious of the studies is the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches.

The National Institutes of Health has awarded an $84 million grant to conduct ISCHEMIA, a study of an early invasive versus conservative strategy in patients with stable CAD and moderate to severe ischemia.

The trial involves 8,000 patients with a left ventricular ejection fraction of 35% or more and at least 10% cardiac ischemia. They will undergo blinded CTA to rule out high-risk left main disease or normal coronary arteries. Then they will be randomized to catheterization and revascularization plus optimal medical therapy or to optimal medical management alone with revascularization reserved for worsening symptoms. Follow-up will be for 3-6 years.

ISCHEMIA is designed to provide answers to questions left open by the COURAGE and BARI 2D trials. The key design difference is that ISCHEMIA participants will be randomized to the invasive or conservative strategy before cardiac catheterization. The study hypothesis is that the invasive strategy will prove superior in terms of the primary composite end point of cardiovascular death, MI, or adjudicated hospitalization for unstable angina, heart failure, or cardiac arrest. Secondary end points will include cost-effectiveness and quality of life measures.

Dr. Udelson declared having no financial conflicts.

DENVER – The historically shaky evidence base for cardiac imaging strategies is in the midst of being shored up by a strong new foundation.

Just a couple of years ago, analysts concluded that cardiac imaging guidelines have among the weakest supporting evidence bases of any of the 53 American College of Cardiology/American Heart Association practice guidelines they looked at. The investigators found that only 2.4% of the evidence supporting the imaging guidelines had a level of evidence of A, meaning supported by multiple randomized trials. Thirty-seven percent of the evidence was level B, coming from multiple observational studies. Another 17% was based on expert opinion, and the rest of the imaging guideline recommendations were not supported by any conclusive evidence (JAMA 2009;301:831-41).

All that is clearly in the process of changing, and in a big way, Dr. James E. Udelson observed at the annual meeting of the American Society of Nuclear Cardiology.

An unprecedented raft of multicenter randomized trials is underway in patients with chest pain. The government-supported studies range in size from 4,300 to 10,000 patients. They are variously aimed at determining whether anatomic imaging via coronary CT angiography (CTA) or functional imaging by SPECT myocardial perfusion imaging stress ECG, or stress echocardiography is the best initial strategy for the diagnosis of coronary artery disease, and at using imaging results to identify optimal management strategies, explained Dr. Udelson, chief of cardiology and director of the nuclear cardiology laboratory at Tufts Medical Center, Boston.

Here’s what’s underway:

• PROMISE. The PROspective Multicenter Imaging Study for Evaluation of chest pain), funded by the National Heart, Lung, and Blood Institute, involves 10,000 patients with symptoms suggestive of CAD and low to intermediate pretest probability of CAD. They’ll be randomized to CTA or functional imaging by SPECT myocardial perfusion imaging, stress ECG, or stress echo, with the study results immediately available to the care team for use in management decisions.

The primary end point is the 30-month composite of death, MI, major complications due to cardiac catheterization, or hospitalization for unstable angina. The study hypothesis is that noninvasive anatomic imaging via CTA will result in superior long-term outcomes.

Enrollment is progressing quickly, with 2,800 randomized patients, according to Dr. Udelson, who is a PROMISE investigator.

• RESCUE. In the Randomized Evaluation of patients with Stable angina Comparing Utilization of diagnostic Examinations, 4,300 symptomatic outpatients are being randomized to SPECT myocardial perfusion imaging or CTA, with their subsequent management being driven by an algorithm based on their test results. The hypothesis here is that CTA will be associated with no increase in adverse events, similar outcomes, lower cost, less radiation exposure, and resultant superior cost-effectiveness. Dr. Udelson is an investigator in RESCUE, which is supported by the Agency for Healthcare Research and Quality and the American College of Radiology Imaging Network.

• ISCHEMIA. The most ambitious of the studies is the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches.

The National Institutes of Health has awarded an $84 million grant to conduct ISCHEMIA, a study of an early invasive versus conservative strategy in patients with stable CAD and moderate to severe ischemia.

The trial involves 8,000 patients with a left ventricular ejection fraction of 35% or more and at least 10% cardiac ischemia. They will undergo blinded CTA to rule out high-risk left main disease or normal coronary arteries. Then they will be randomized to catheterization and revascularization plus optimal medical therapy or to optimal medical management alone with revascularization reserved for worsening symptoms. Follow-up will be for 3-6 years.

ISCHEMIA is designed to provide answers to questions left open by the COURAGE and BARI 2D trials. The key design difference is that ISCHEMIA participants will be randomized to the invasive or conservative strategy before cardiac catheterization. The study hypothesis is that the invasive strategy will prove superior in terms of the primary composite end point of cardiovascular death, MI, or adjudicated hospitalization for unstable angina, heart failure, or cardiac arrest. Secondary end points will include cost-effectiveness and quality of life measures.

Dr. Udelson declared having no financial conflicts.

DENVER – The historically shaky evidence base for cardiac imaging strategies is in the midst of being shored up by a strong new foundation.

Just a couple of years ago, analysts concluded that cardiac imaging guidelines have among the weakest supporting evidence bases of any of the 53 American College of Cardiology/American Heart Association practice guidelines they looked at. The investigators found that only 2.4% of the evidence supporting the imaging guidelines had a level of evidence of A, meaning supported by multiple randomized trials. Thirty-seven percent of the evidence was level B, coming from multiple observational studies. Another 17% was based on expert opinion, and the rest of the imaging guideline recommendations were not supported by any conclusive evidence (JAMA 2009;301:831-41).

All that is clearly in the process of changing, and in a big way, Dr. James E. Udelson observed at the annual meeting of the American Society of Nuclear Cardiology.

An unprecedented raft of multicenter randomized trials is underway in patients with chest pain. The government-supported studies range in size from 4,300 to 10,000 patients. They are variously aimed at determining whether anatomic imaging via coronary CT angiography (CTA) or functional imaging by SPECT myocardial perfusion imaging stress ECG, or stress echocardiography is the best initial strategy for the diagnosis of coronary artery disease, and at using imaging results to identify optimal management strategies, explained Dr. Udelson, chief of cardiology and director of the nuclear cardiology laboratory at Tufts Medical Center, Boston.

Here’s what’s underway:

• PROMISE. The PROspective Multicenter Imaging Study for Evaluation of chest pain), funded by the National Heart, Lung, and Blood Institute, involves 10,000 patients with symptoms suggestive of CAD and low to intermediate pretest probability of CAD. They’ll be randomized to CTA or functional imaging by SPECT myocardial perfusion imaging, stress ECG, or stress echo, with the study results immediately available to the care team for use in management decisions.

The primary end point is the 30-month composite of death, MI, major complications due to cardiac catheterization, or hospitalization for unstable angina. The study hypothesis is that noninvasive anatomic imaging via CTA will result in superior long-term outcomes.

Enrollment is progressing quickly, with 2,800 randomized patients, according to Dr. Udelson, who is a PROMISE investigator.

• RESCUE. In the Randomized Evaluation of patients with Stable angina Comparing Utilization of diagnostic Examinations, 4,300 symptomatic outpatients are being randomized to SPECT myocardial perfusion imaging or CTA, with their subsequent management being driven by an algorithm based on their test results. The hypothesis here is that CTA will be associated with no increase in adverse events, similar outcomes, lower cost, less radiation exposure, and resultant superior cost-effectiveness. Dr. Udelson is an investigator in RESCUE, which is supported by the Agency for Healthcare Research and Quality and the American College of Radiology Imaging Network.

• ISCHEMIA. The most ambitious of the studies is the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches.

The National Institutes of Health has awarded an $84 million grant to conduct ISCHEMIA, a study of an early invasive versus conservative strategy in patients with stable CAD and moderate to severe ischemia.

The trial involves 8,000 patients with a left ventricular ejection fraction of 35% or more and at least 10% cardiac ischemia. They will undergo blinded CTA to rule out high-risk left main disease or normal coronary arteries. Then they will be randomized to catheterization and revascularization plus optimal medical therapy or to optimal medical management alone with revascularization reserved for worsening symptoms. Follow-up will be for 3-6 years.

ISCHEMIA is designed to provide answers to questions left open by the COURAGE and BARI 2D trials. The key design difference is that ISCHEMIA participants will be randomized to the invasive or conservative strategy before cardiac catheterization. The study hypothesis is that the invasive strategy will prove superior in terms of the primary composite end point of cardiovascular death, MI, or adjudicated hospitalization for unstable angina, heart failure, or cardiac arrest. Secondary end points will include cost-effectiveness and quality of life measures.

Dr. Udelson declared having no financial conflicts.

DENVER – The added prognostic value gained by measuring coronary flow reserve in addition to myocardial perfusion for predicting the risk of cardiac events is a major emerging theme in cardiac nuclear imaging.

The impetus for developing PET quantitation of coronary flow reserve as a tool for evaluating cardiac event risk in patients with known or suspected CAD lies in the relatively recent recognition that a normal or low-risk conventional single-photon emission computed tomography (SPECT) myocardial perfusion imaging study is no guarantee of a low event risk, Dr. George A. Beller noted at the annual meeting of the American Society of Nuclear Cardiology.

"In order to identify those patients with normal or low-risk perfusion scans who really are high risk, we need to do more than just look at relative perfusion," he explained. "Myocardial flow reserve as assessed by PET is emerging now as a really good adjunct to just looking at relative uptake."

Italian investigators recently utilized dynamic SPECT imaging to assess coronary flow reserve in 58 patients with a normal myocardial perfusion study. In the 20 patients with normal coronary flow reserve as well as normal perfusion, the cardiac event rate was just 0.7% per year. In the 38 with normal perfusion along with an abnormally low coronary flow reserve, however, the event rate was 5.2% per year (J. Nucl. Cardiol. 2011;18:612-9).

"This is a substantial sevenfold increase in event rate in those with what we would consider a normal scan with normal perfusion," commented Dr. Beller of the University of Virginia, Charlottesville.

PET offers several key advantages over SPECT for assessment of coronary flow reserve, the most important being that it provides accurate quantification of the extent of abnormal regional myocardial blood flow reserve. In addition, it readily detects microvascular dysfunction, and it also picks up balanced ischemia, which often results in a false-negative SPECT myocardial perfusion imaging study, he continued.

"Myocardial flow reserve as assessed by PET is emerging now as a really good adjunct to just looking at relative uptake."

A recent study by investigators at the University of Ottawa Heart Institute National Cardiac PET Center showed that quantitation of coronary flow reserve using rubidium-82 PET predicted hard cardiac events independently of summed stress scores for myocardial ischemia.

In 704 consecutive patients prospectively followed for a median of 387 days after testing, those with a summed symptom score of less than 4, indicative of normal myocardial perfusion, plus normal coronary flow reserve had a 1.3% incidence of cardiac death or MI. In contrast, patients with a summed symptom score below 4 and abnormally low coronary flow reserve had a significantly higher 2.0% event rate, while those with a summed symptom score of 4 or higher plus abnormal coronary flow reserve had an 11.1% cardiac event rate. Patients with abnormal myocardial perfusion and normal coronary flow reserve had a 1.1% incidence of cardiac events (J. Am. Coll. Cardiol. 2011;58:740-8).

Similarly, investigators at Johns Hopkins University, Baltimore, recently demonstrated that a finding of globally impaired myocardial flow reserve was a potent independent predictor of near-term cardiovascular events.

They utilized rubidium-82 PET to quantify global myocardial flow reserve in 275 patients referred for perfusion imaging and subsequently followed for an average of 1 year. In an age-adjusted multivariate analysis, a finding of regional perfusion defects was independently associated with a 2.5-fold increased risk of cardiac events, confirming a long-established relationship. But in addition, a global myocardial flow reserve below the median value was also an independent predictor of cardiac events, with an associated 2.9-fold increased risk (J. Nucl. Med. 2011;52:726-32).

On the basis of these and other compelling studies reported in the last year or two, Dr. Beller offered the following algorithm for noninvasive testing to predict the risk of cardiac events in patients with stable CAD: Those who can perform more than 10 METs (metabolic equivalents) of exercise on the treadmill are at very low risk and warrant being placed on optimal medical therapy, with crossover to an invasive strategy only if symptoms worsen. Patients less than 5% left ventricular ischemia and normal coronary flow reserve also belong in this low-risk category.

A high-risk test is defined by 10%-15% left ventricular ischemia or markedly reduced coronary flow reserve, even in the presence of only a mild perfusion defect. These are patients for whom consideration should be given to an invasive strategy coupled with optimal medical therapy.

For patients with mild ischemia – that is, 5%-9% – a normal ejection fraction, and either a normal or only a small focal area of diminished coronary flow reserve, optimal medical therapy and follow-up stress imaging is an appropriate approach, Dr. Beller added.

He declared having no financial conflicts.

DENVER – The added prognostic value gained by measuring coronary flow reserve in addition to myocardial perfusion for predicting the risk of cardiac events is a major emerging theme in cardiac nuclear imaging.

The impetus for developing PET quantitation of coronary flow reserve as a tool for evaluating cardiac event risk in patients with known or suspected CAD lies in the relatively recent recognition that a normal or low-risk conventional single-photon emission computed tomography (SPECT) myocardial perfusion imaging study is no guarantee of a low event risk, Dr. George A. Beller noted at the annual meeting of the American Society of Nuclear Cardiology.

"In order to identify those patients with normal or low-risk perfusion scans who really are high risk, we need to do more than just look at relative perfusion," he explained. "Myocardial flow reserve as assessed by PET is emerging now as a really good adjunct to just looking at relative uptake."

Italian investigators recently utilized dynamic SPECT imaging to assess coronary flow reserve in 58 patients with a normal myocardial perfusion study. In the 20 patients with normal coronary flow reserve as well as normal perfusion, the cardiac event rate was just 0.7% per year. In the 38 with normal perfusion along with an abnormally low coronary flow reserve, however, the event rate was 5.2% per year (J. Nucl. Cardiol. 2011;18:612-9).

"This is a substantial sevenfold increase in event rate in those with what we would consider a normal scan with normal perfusion," commented Dr. Beller of the University of Virginia, Charlottesville.

PET offers several key advantages over SPECT for assessment of coronary flow reserve, the most important being that it provides accurate quantification of the extent of abnormal regional myocardial blood flow reserve. In addition, it readily detects microvascular dysfunction, and it also picks up balanced ischemia, which often results in a false-negative SPECT myocardial perfusion imaging study, he continued.

"Myocardial flow reserve as assessed by PET is emerging now as a really good adjunct to just looking at relative uptake."

A recent study by investigators at the University of Ottawa Heart Institute National Cardiac PET Center showed that quantitation of coronary flow reserve using rubidium-82 PET predicted hard cardiac events independently of summed stress scores for myocardial ischemia.

In 704 consecutive patients prospectively followed for a median of 387 days after testing, those with a summed symptom score of less than 4, indicative of normal myocardial perfusion, plus normal coronary flow reserve had a 1.3% incidence of cardiac death or MI. In contrast, patients with a summed symptom score below 4 and abnormally low coronary flow reserve had a significantly higher 2.0% event rate, while those with a summed symptom score of 4 or higher plus abnormal coronary flow reserve had an 11.1% cardiac event rate. Patients with abnormal myocardial perfusion and normal coronary flow reserve had a 1.1% incidence of cardiac events (J. Am. Coll. Cardiol. 2011;58:740-8).

Similarly, investigators at Johns Hopkins University, Baltimore, recently demonstrated that a finding of globally impaired myocardial flow reserve was a potent independent predictor of near-term cardiovascular events.

They utilized rubidium-82 PET to quantify global myocardial flow reserve in 275 patients referred for perfusion imaging and subsequently followed for an average of 1 year. In an age-adjusted multivariate analysis, a finding of regional perfusion defects was independently associated with a 2.5-fold increased risk of cardiac events, confirming a long-established relationship. But in addition, a global myocardial flow reserve below the median value was also an independent predictor of cardiac events, with an associated 2.9-fold increased risk (J. Nucl. Med. 2011;52:726-32).

On the basis of these and other compelling studies reported in the last year or two, Dr. Beller offered the following algorithm for noninvasive testing to predict the risk of cardiac events in patients with stable CAD: Those who can perform more than 10 METs (metabolic equivalents) of exercise on the treadmill are at very low risk and warrant being placed on optimal medical therapy, with crossover to an invasive strategy only if symptoms worsen. Patients less than 5% left ventricular ischemia and normal coronary flow reserve also belong in this low-risk category.

A high-risk test is defined by 10%-15% left ventricular ischemia or markedly reduced coronary flow reserve, even in the presence of only a mild perfusion defect. These are patients for whom consideration should be given to an invasive strategy coupled with optimal medical therapy.

For patients with mild ischemia – that is, 5%-9% – a normal ejection fraction, and either a normal or only a small focal area of diminished coronary flow reserve, optimal medical therapy and follow-up stress imaging is an appropriate approach, Dr. Beller added.

He declared having no financial conflicts.

DENVER – The added prognostic value gained by measuring coronary flow reserve in addition to myocardial perfusion for predicting the risk of cardiac events is a major emerging theme in cardiac nuclear imaging.

The impetus for developing PET quantitation of coronary flow reserve as a tool for evaluating cardiac event risk in patients with known or suspected CAD lies in the relatively recent recognition that a normal or low-risk conventional single-photon emission computed tomography (SPECT) myocardial perfusion imaging study is no guarantee of a low event risk, Dr. George A. Beller noted at the annual meeting of the American Society of Nuclear Cardiology.

"In order to identify those patients with normal or low-risk perfusion scans who really are high risk, we need to do more than just look at relative perfusion," he explained. "Myocardial flow reserve as assessed by PET is emerging now as a really good adjunct to just looking at relative uptake."

Italian investigators recently utilized dynamic SPECT imaging to assess coronary flow reserve in 58 patients with a normal myocardial perfusion study. In the 20 patients with normal coronary flow reserve as well as normal perfusion, the cardiac event rate was just 0.7% per year. In the 38 with normal perfusion along with an abnormally low coronary flow reserve, however, the event rate was 5.2% per year (J. Nucl. Cardiol. 2011;18:612-9).

"This is a substantial sevenfold increase in event rate in those with what we would consider a normal scan with normal perfusion," commented Dr. Beller of the University of Virginia, Charlottesville.

PET offers several key advantages over SPECT for assessment of coronary flow reserve, the most important being that it provides accurate quantification of the extent of abnormal regional myocardial blood flow reserve. In addition, it readily detects microvascular dysfunction, and it also picks up balanced ischemia, which often results in a false-negative SPECT myocardial perfusion imaging study, he continued.

"Myocardial flow reserve as assessed by PET is emerging now as a really good adjunct to just looking at relative uptake."

A recent study by investigators at the University of Ottawa Heart Institute National Cardiac PET Center showed that quantitation of coronary flow reserve using rubidium-82 PET predicted hard cardiac events independently of summed stress scores for myocardial ischemia.

In 704 consecutive patients prospectively followed for a median of 387 days after testing, those with a summed symptom score of less than 4, indicative of normal myocardial perfusion, plus normal coronary flow reserve had a 1.3% incidence of cardiac death or MI. In contrast, patients with a summed symptom score below 4 and abnormally low coronary flow reserve had a significantly higher 2.0% event rate, while those with a summed symptom score of 4 or higher plus abnormal coronary flow reserve had an 11.1% cardiac event rate. Patients with abnormal myocardial perfusion and normal coronary flow reserve had a 1.1% incidence of cardiac events (J. Am. Coll. Cardiol. 2011;58:740-8).

Similarly, investigators at Johns Hopkins University, Baltimore, recently demonstrated that a finding of globally impaired myocardial flow reserve was a potent independent predictor of near-term cardiovascular events.

They utilized rubidium-82 PET to quantify global myocardial flow reserve in 275 patients referred for perfusion imaging and subsequently followed for an average of 1 year. In an age-adjusted multivariate analysis, a finding of regional perfusion defects was independently associated with a 2.5-fold increased risk of cardiac events, confirming a long-established relationship. But in addition, a global myocardial flow reserve below the median value was also an independent predictor of cardiac events, with an associated 2.9-fold increased risk (J. Nucl. Med. 2011;52:726-32).

On the basis of these and other compelling studies reported in the last year or two, Dr. Beller offered the following algorithm for noninvasive testing to predict the risk of cardiac events in patients with stable CAD: Those who can perform more than 10 METs (metabolic equivalents) of exercise on the treadmill are at very low risk and warrant being placed on optimal medical therapy, with crossover to an invasive strategy only if symptoms worsen. Patients less than 5% left ventricular ischemia and normal coronary flow reserve also belong in this low-risk category.

A high-risk test is defined by 10%-15% left ventricular ischemia or markedly reduced coronary flow reserve, even in the presence of only a mild perfusion defect. These are patients for whom consideration should be given to an invasive strategy coupled with optimal medical therapy.

For patients with mild ischemia – that is, 5%-9% – a normal ejection fraction, and either a normal or only a small focal area of diminished coronary flow reserve, optimal medical therapy and follow-up stress imaging is an appropriate approach, Dr. Beller added.

He declared having no financial conflicts.

DENVER – Nuclear medicine specialists are feeling the brunt of increased public anxiety and regulatory concern regarding patient radiation exposures.

Nuclear cardiologists, in particular, find themselves in the crosshairs as a result of recent evidence of inappropriate overutilization of myocardial perfusion imaging. The profession has responded with a campaign aimed at defining appropriate use scenarios for practitioners and encouraging adoption of newer techniques that reduce radiation exposure while retaining high image quality.

"Based on these recommendations, we expect that for the population of patients referred for SPECT or PET myocardial perfusion imaging, on average a total radiation exposure of 9 mSv or less can be achieved in 50% of studies by 2014," Dr. Manuel D. Cerqueira said at the annual meeting of the American Society of Nuclear Cardiology.

Meeting that goal will require, for example, doing fewer separate-day, stress/rest technetium-99 myocardial perfusion imaging tests, which typically entail 13-16 mSv of radiation exposure. Also, the American Society of Nuclear Cardiology (ASNC) recommendations urge consideration of stress echocardiography as an alternative to nuclear imaging in younger patients because the diagnostic accuracy may be comparable and they can avoid radiation exposure altogether. In addition, the ASNC report discourages thallium-201–based imaging protocols, which involve 22-31 mSv of radiation exposure, noted Dr. Cerqueira, who was first author of the recommendations (J. Nucl. Cardiol. 2010;17:709-18), and is professor of radiology and medicine at Case Western Reserve University, Cleveland.

Something that has nuclear medicine specialists and interventional radiologists greatly concerned, according to Robert W. Atcher, Ph.D., is a proposed Nuclear Regulatory Commission (NRC) policy change that would lower the occupational radiation exposure limit from 5 to 2 rem (Roentgen equivalent man).

"The most affected groups in our field are technologists with a heavy PET [positron emission tomography] patient flow, cyclotron engineers, maintenance personnel, and radiochemists synthesizing PET tracers and therapeutic compounds. This is potentially devastating to us, because if we lower the limit then we have to double the number of people who are responsible for doing the same number of imaging studies, with no way to collect any more reimbursement to handle that task. In essence, they’re threatening to devastate our ability to do imaging," said Dr. Atcher, director of the National Isotope Development Center at the U.S. Department of Energy.

The NRC got an earful from concerned physicians and nonphysician scientists at hearings on the proposed changes held last year in Los Angeles, Houston, and Washington. The agency has not yet announced whether it plans to go ahead.

Another instance of what Dr. Atcher characterized as "regulatory overreacting" involves congressional interest in requiring hospitalization for patients who have received iodine-131. He and others have testified that there is no scientific evidence of risk to patients’ families or the general public if current guidelines for I-131 use are followed. Congressional representatives were also told that hospitalizing I-131 recipients would cost in excess of $600 million annually. In addition, critics of the idea pointed out that the risk of acquiring a serious methicillin-resistant Staphylococcus aureus infection during a hospital stay is quite real, said Dr. Atcher, a former president of the Society for Nuclear Medicine.

The new mantra at ASNC is "patient-centered imaging." The group’s recommendations for reducing radiation exposure from myocardial perfusion imaging emphasize appropriate patient selection, the use of standardized imaging protocols, radiotracers with shorter half-lives, weight-based dosing, and improved imaging systems.

Dr. E. Gordon DePuey highlighted the many new methods of optimizing image quality that have reached the market. These include resolution recovery and noise modeling software that provides superior image quality with shortened radiation exposure time. "All vendors now offer software that does this," he pointed out.

Also, hardware enhancements such as cardiofocal collimation are making a big difference. This particular technology allows half-time SPECT (single-photon emission computed tomography) with 100% myocardial radiation count density, explained Dr. DePuey of Columbia University, New York.

"All these new hardware and software methods out there are major advancements in nuclear cardiology. They need to be very seriously considered and incorporated in your practice, because they are really the keys to allowing you to decrease the radiation dose to your patients," he said.

Dr. Cerqueira drew attention to a large study that concluded myocardial perfusion imaging accounts for 22% of the total effective radiation dose accumulated from all nuclear medicine imaging procedures. Abdominal CT was the second biggest contributor, at 18% (N. Engl. J. Med. 2009;361:849-57).

Also concerning was a recent study using the very large UnitedHealthcare patient database. It showed that myocardial perfusion imaging accounted for 80% of the cumulative effective radiation dose from all cardiac imaging procedures in women age 18-34 years (J. Am. Coll. Cardiol. 2010;56:702-11).

"That’s a young population of women of childbearing age where you really wouldn’t expect a great many of these myocardial perfusion imaging studies to be done," Dr. Cerqueira commented.

He noted that the ASNC recommendations urge reserving myocardial perfusion imaging for patients in whom it has the greatest clinical utility: those at intermediate risk of coronary artery disease, patients requiring prognostic or management information, and those with persistent unexplained symptoms.

Dr. DePuey disclosed that he serves as an adviser to UltraSPECT and Dogwood Pharmaceuticals. The other speakers declared having no relevant financial interests.

DENVER – Nuclear medicine specialists are feeling the brunt of increased public anxiety and regulatory concern regarding patient radiation exposures.

Nuclear cardiologists, in particular, find themselves in the crosshairs as a result of recent evidence of inappropriate overutilization of myocardial perfusion imaging. The profession has responded with a campaign aimed at defining appropriate use scenarios for practitioners and encouraging adoption of newer techniques that reduce radiation exposure while retaining high image quality.

"Based on these recommendations, we expect that for the population of patients referred for SPECT or PET myocardial perfusion imaging, on average a total radiation exposure of 9 mSv or less can be achieved in 50% of studies by 2014," Dr. Manuel D. Cerqueira said at the annual meeting of the American Society of Nuclear Cardiology.

Meeting that goal will require, for example, doing fewer separate-day, stress/rest technetium-99 myocardial perfusion imaging tests, which typically entail 13-16 mSv of radiation exposure. Also, the American Society of Nuclear Cardiology (ASNC) recommendations urge consideration of stress echocardiography as an alternative to nuclear imaging in younger patients because the diagnostic accuracy may be comparable and they can avoid radiation exposure altogether. In addition, the ASNC report discourages thallium-201–based imaging protocols, which involve 22-31 mSv of radiation exposure, noted Dr. Cerqueira, who was first author of the recommendations (J. Nucl. Cardiol. 2010;17:709-18), and is professor of radiology and medicine at Case Western Reserve University, Cleveland.

Something that has nuclear medicine specialists and interventional radiologists greatly concerned, according to Robert W. Atcher, Ph.D., is a proposed Nuclear Regulatory Commission (NRC) policy change that would lower the occupational radiation exposure limit from 5 to 2 rem (Roentgen equivalent man).

"The most affected groups in our field are technologists with a heavy PET [positron emission tomography] patient flow, cyclotron engineers, maintenance personnel, and radiochemists synthesizing PET tracers and therapeutic compounds. This is potentially devastating to us, because if we lower the limit then we have to double the number of people who are responsible for doing the same number of imaging studies, with no way to collect any more reimbursement to handle that task. In essence, they’re threatening to devastate our ability to do imaging," said Dr. Atcher, director of the National Isotope Development Center at the U.S. Department of Energy.

The NRC got an earful from concerned physicians and nonphysician scientists at hearings on the proposed changes held last year in Los Angeles, Houston, and Washington. The agency has not yet announced whether it plans to go ahead.

Another instance of what Dr. Atcher characterized as "regulatory overreacting" involves congressional interest in requiring hospitalization for patients who have received iodine-131. He and others have testified that there is no scientific evidence of risk to patients’ families or the general public if current guidelines for I-131 use are followed. Congressional representatives were also told that hospitalizing I-131 recipients would cost in excess of $600 million annually. In addition, critics of the idea pointed out that the risk of acquiring a serious methicillin-resistant Staphylococcus aureus infection during a hospital stay is quite real, said Dr. Atcher, a former president of the Society for Nuclear Medicine.

The new mantra at ASNC is "patient-centered imaging." The group’s recommendations for reducing radiation exposure from myocardial perfusion imaging emphasize appropriate patient selection, the use of standardized imaging protocols, radiotracers with shorter half-lives, weight-based dosing, and improved imaging systems.

Dr. E. Gordon DePuey highlighted the many new methods of optimizing image quality that have reached the market. These include resolution recovery and noise modeling software that provides superior image quality with shortened radiation exposure time. "All vendors now offer software that does this," he pointed out.

Also, hardware enhancements such as cardiofocal collimation are making a big difference. This particular technology allows half-time SPECT (single-photon emission computed tomography) with 100% myocardial radiation count density, explained Dr. DePuey of Columbia University, New York.

"All these new hardware and software methods out there are major advancements in nuclear cardiology. They need to be very seriously considered and incorporated in your practice, because they are really the keys to allowing you to decrease the radiation dose to your patients," he said.

Dr. Cerqueira drew attention to a large study that concluded myocardial perfusion imaging accounts for 22% of the total effective radiation dose accumulated from all nuclear medicine imaging procedures. Abdominal CT was the second biggest contributor, at 18% (N. Engl. J. Med. 2009;361:849-57).

Also concerning was a recent study using the very large UnitedHealthcare patient database. It showed that myocardial perfusion imaging accounted for 80% of the cumulative effective radiation dose from all cardiac imaging procedures in women age 18-34 years (J. Am. Coll. Cardiol. 2010;56:702-11).

"That’s a young population of women of childbearing age where you really wouldn’t expect a great many of these myocardial perfusion imaging studies to be done," Dr. Cerqueira commented.

He noted that the ASNC recommendations urge reserving myocardial perfusion imaging for patients in whom it has the greatest clinical utility: those at intermediate risk of coronary artery disease, patients requiring prognostic or management information, and those with persistent unexplained symptoms.

Dr. DePuey disclosed that he serves as an adviser to UltraSPECT and Dogwood Pharmaceuticals. The other speakers declared having no relevant financial interests.

DENVER – Nuclear medicine specialists are feeling the brunt of increased public anxiety and regulatory concern regarding patient radiation exposures.

Nuclear cardiologists, in particular, find themselves in the crosshairs as a result of recent evidence of inappropriate overutilization of myocardial perfusion imaging. The profession has responded with a campaign aimed at defining appropriate use scenarios for practitioners and encouraging adoption of newer techniques that reduce radiation exposure while retaining high image quality.

"Based on these recommendations, we expect that for the population of patients referred for SPECT or PET myocardial perfusion imaging, on average a total radiation exposure of 9 mSv or less can be achieved in 50% of studies by 2014," Dr. Manuel D. Cerqueira said at the annual meeting of the American Society of Nuclear Cardiology.

Meeting that goal will require, for example, doing fewer separate-day, stress/rest technetium-99 myocardial perfusion imaging tests, which typically entail 13-16 mSv of radiation exposure. Also, the American Society of Nuclear Cardiology (ASNC) recommendations urge consideration of stress echocardiography as an alternative to nuclear imaging in younger patients because the diagnostic accuracy may be comparable and they can avoid radiation exposure altogether. In addition, the ASNC report discourages thallium-201–based imaging protocols, which involve 22-31 mSv of radiation exposure, noted Dr. Cerqueira, who was first author of the recommendations (J. Nucl. Cardiol. 2010;17:709-18), and is professor of radiology and medicine at Case Western Reserve University, Cleveland.

Something that has nuclear medicine specialists and interventional radiologists greatly concerned, according to Robert W. Atcher, Ph.D., is a proposed Nuclear Regulatory Commission (NRC) policy change that would lower the occupational radiation exposure limit from 5 to 2 rem (Roentgen equivalent man).

"The most affected groups in our field are technologists with a heavy PET [positron emission tomography] patient flow, cyclotron engineers, maintenance personnel, and radiochemists synthesizing PET tracers and therapeutic compounds. This is potentially devastating to us, because if we lower the limit then we have to double the number of people who are responsible for doing the same number of imaging studies, with no way to collect any more reimbursement to handle that task. In essence, they’re threatening to devastate our ability to do imaging," said Dr. Atcher, director of the National Isotope Development Center at the U.S. Department of Energy.

The NRC got an earful from concerned physicians and nonphysician scientists at hearings on the proposed changes held last year in Los Angeles, Houston, and Washington. The agency has not yet announced whether it plans to go ahead.

Another instance of what Dr. Atcher characterized as "regulatory overreacting" involves congressional interest in requiring hospitalization for patients who have received iodine-131. He and others have testified that there is no scientific evidence of risk to patients’ families or the general public if current guidelines for I-131 use are followed. Congressional representatives were also told that hospitalizing I-131 recipients would cost in excess of $600 million annually. In addition, critics of the idea pointed out that the risk of acquiring a serious methicillin-resistant Staphylococcus aureus infection during a hospital stay is quite real, said Dr. Atcher, a former president of the Society for Nuclear Medicine.

The new mantra at ASNC is "patient-centered imaging." The group’s recommendations for reducing radiation exposure from myocardial perfusion imaging emphasize appropriate patient selection, the use of standardized imaging protocols, radiotracers with shorter half-lives, weight-based dosing, and improved imaging systems.

Dr. E. Gordon DePuey highlighted the many new methods of optimizing image quality that have reached the market. These include resolution recovery and noise modeling software that provides superior image quality with shortened radiation exposure time. "All vendors now offer software that does this," he pointed out.

Also, hardware enhancements such as cardiofocal collimation are making a big difference. This particular technology allows half-time SPECT (single-photon emission computed tomography) with 100% myocardial radiation count density, explained Dr. DePuey of Columbia University, New York.

"All these new hardware and software methods out there are major advancements in nuclear cardiology. They need to be very seriously considered and incorporated in your practice, because they are really the keys to allowing you to decrease the radiation dose to your patients," he said.

Dr. Cerqueira drew attention to a large study that concluded myocardial perfusion imaging accounts for 22% of the total effective radiation dose accumulated from all nuclear medicine imaging procedures. Abdominal CT was the second biggest contributor, at 18% (N. Engl. J. Med. 2009;361:849-57).

Also concerning was a recent study using the very large UnitedHealthcare patient database. It showed that myocardial perfusion imaging accounted for 80% of the cumulative effective radiation dose from all cardiac imaging procedures in women age 18-34 years (J. Am. Coll. Cardiol. 2010;56:702-11).

"That’s a young population of women of childbearing age where you really wouldn’t expect a great many of these myocardial perfusion imaging studies to be done," Dr. Cerqueira commented.

He noted that the ASNC recommendations urge reserving myocardial perfusion imaging for patients in whom it has the greatest clinical utility: those at intermediate risk of coronary artery disease, patients requiring prognostic or management information, and those with persistent unexplained symptoms.

Dr. DePuey disclosed that he serves as an adviser to UltraSPECT and Dogwood Pharmaceuticals. The other speakers declared having no relevant financial interests.

DENVER – Physicians making referrals for cardiac stress testing often underestimate their patients’ ability to exercise to target heart rate, according to Dr. Michael Ross.

Here’s what can happen as a result: In a prospective series of 120 consecutive patients referred for pharmacologic myocardial perfusion imaging stress testing by primary care physicians, surgeons, and cardiologists, 60% of the patients were able to mount the treadmill and exercise to 85% of their estimated maximum heart rate, he reported at the annual meeting of American Society of Nuclear Cardiology.

Primary care physicians were significantly more likely than were cardiologists or surgeons to order a pharmacologic stress test in patients who did not need one because they were able to complete the less costly exercise stress test.

Is that because primary care physicians don’t know their patients and their physical capacities as well as other physicians do? Highly unlikely. Instead, it appears they are more concerned that if they order an exercise stress test and a patient can’t complete it, they’ll have to reorder the test – this time using pharmacologic stress – with the attendant inconvenience and delay, according to Dr. Ross of Northwestern University, Chicago.

In a multivariate logistic regression analysis, the only independent predictors of failure to reach target heart rate were being on a beta-blocker and having diabetes.

Dr. Ross said he had no relevant financial disclosures.

DENVER – Physicians making referrals for cardiac stress testing often underestimate their patients’ ability to exercise to target heart rate, according to Dr. Michael Ross.

Here’s what can happen as a result: In a prospective series of 120 consecutive patients referred for pharmacologic myocardial perfusion imaging stress testing by primary care physicians, surgeons, and cardiologists, 60% of the patients were able to mount the treadmill and exercise to 85% of their estimated maximum heart rate, he reported at the annual meeting of American Society of Nuclear Cardiology.

Primary care physicians were significantly more likely than were cardiologists or surgeons to order a pharmacologic stress test in patients who did not need one because they were able to complete the less costly exercise stress test.

Is that because primary care physicians don’t know their patients and their physical capacities as well as other physicians do? Highly unlikely. Instead, it appears they are more concerned that if they order an exercise stress test and a patient can’t complete it, they’ll have to reorder the test – this time using pharmacologic stress – with the attendant inconvenience and delay, according to Dr. Ross of Northwestern University, Chicago.

In a multivariate logistic regression analysis, the only independent predictors of failure to reach target heart rate were being on a beta-blocker and having diabetes.

Dr. Ross said he had no relevant financial disclosures.

DENVER – Physicians making referrals for cardiac stress testing often underestimate their patients’ ability to exercise to target heart rate, according to Dr. Michael Ross.

Here’s what can happen as a result: In a prospective series of 120 consecutive patients referred for pharmacologic myocardial perfusion imaging stress testing by primary care physicians, surgeons, and cardiologists, 60% of the patients were able to mount the treadmill and exercise to 85% of their estimated maximum heart rate, he reported at the annual meeting of American Society of Nuclear Cardiology.

Primary care physicians were significantly more likely than were cardiologists or surgeons to order a pharmacologic stress test in patients who did not need one because they were able to complete the less costly exercise stress test.

Is that because primary care physicians don’t know their patients and their physical capacities as well as other physicians do? Highly unlikely. Instead, it appears they are more concerned that if they order an exercise stress test and a patient can’t complete it, they’ll have to reorder the test – this time using pharmacologic stress – with the attendant inconvenience and delay, according to Dr. Ross of Northwestern University, Chicago.

In a multivariate logistic regression analysis, the only independent predictors of failure to reach target heart rate were being on a beta-blocker and having diabetes.

Dr. Ross said he had no relevant financial disclosures.

DENVER – The majority of nuclear cardiology labs are not utilizing the American College of Cardiology appropriate use criteria for myocardial perfusion imaging, according to the preliminary results of an American Society of Nuclear Cardiology membership survey.

The revelation that only 48% of nuclear cardiology imaging labs employ the ACC appropriate use criteria is disturbing. It comes at a time when nuclear cardiologists are already drawing heat from payers, clinicians, patients, and Congress for perceived overutilization of testing and a casual attitude toward patient exposure to radiation.

The ACC’s appropriate use criteria (AUC) program is a high-profile quality improvement initiative. The myocardial perfusion imaging AUC were developed jointly by the ACC, ASNC, and other key specialty societies. Myocardial perfusion imaging (MPI) was the first topic selected for the program, which has since gone on to develop AUC for other common cardiovascular tests and procedures. MPI was selected to go first because of concerns raised by the explosive growth and substantial regional variation in the procedures. The initial version of the MPI AUC was published in 2005, with an updated rendition appearing 2 years ago (J. Am. Coll. Cardiol. 2009;53:2201-9).

ASNC President Leslee J. Shaw, Ph.D., presented the preliminary membership survey results during her presidential address at the annual meeting of the American Society of Nuclear Cardiology. She also took that occasion to unveil an ambitious new multifaceted ASNC campaign called "Excellence in Imaging." The program is designed to improve the practice of nuclear cardiology through education and advocacy, and by fostering high-quality research that demonstrates nuclear imaging’s clinical value. ASNC members who take the Excellence in Imaging pledge commit themselves to following the AUC.

"By taking a proactive stance on defining quality in nuclear cardiology and demonstrating our members’ commitment to these defined quality measures, ASNC will lead the discussion about appropriate use and set the standards by which our patients receive optimal care," promised Dr. Shaw, professor of medicine at Emory University, Atlanta.

"What the survey results say to me is that we need to do a better job of providing you with tools where you can see the value in improving your process of care, and how the AUC can be utilized to actually identify appropriate patient referral patterns and track your success. This is increasingly going to be a performance metric. Your rating for appropriate test candidates is going to be used as a quality metric," she explained.

The educational portion of the Excellence in Imaging campaign will not only include continuing medical education that is designed to raise the quality of imaging by ASNC members, but also webinars for referring physicians aimed at fostering appropriate referral patterns. Clinical decision support tools are being developed that can be embedded in smart phones to assist referring physicians in selecting the optimal test for a given patient, rather than leaving the testing decision to be made downstream when the patient arrives at the nuclear cardiology clinic. There will also be public education efforts to dispel widespread misconceptions about radiation safety.

Later, Dr. Manuel D. Cerqueira observed that shifting the timing of appropriate test decision making to the point when testing is ordered by referring physicians is "easy to say, hard to do."

No matter how many conversations he has with emergency department physicians at outlying hospitals about not sending him low-risk, inappropriate candidates for imaging procedures involving ionizing radiation exposure when there are better nonradioactive tests available, they continue to do so.

"They’re worried about liability, they’re worried about their 1-year contract that gets reviewed by the hospital, and they’re worried about the pressure the hospital puts on them to do more procedures that are lucrative for the hospital," said Dr. Cerqueira, professor of radiology and medicine and chairman of the nuclear medicine imaging institute at the Cleveland Clinic Foundation.

In a separate presentation, Dr. Robert C. Hendel, who chaired the writing group for the updated MPI AUC, said a dozen studies presented in the past 5 years demonstrate that 10%-15% of all MPIs are inappropriate, as defined by the AUC.

"Basically, if it’s an inappropriate indication, by definition the risks exceed the benefits. The best radiation safety we can do is not to perform the test – not to expose the patient – when it’s not necessary," explained Dr. Hendel, professor of medicine and radiology and director of cardiac imaging and outpatient services at the University of Miami.

He led a six-center study called SPECT-MPI involving roughly 6,000 consecutive patients who underwent single photon emission CT. Overall, inappropriate use of the procedure occurred in 14.4% of patients, with rates ranging from 4% to 22% among the practices.

The SPECT-MPI study identified the major problem areas for inappropriate utilization. Topping the list was the use of MPI to detect CAD in asymptomatic patients at low risk for coronary heart disease; this accounted for 45% of all inappropriate tests and 6% of total testing.

The five most common inappropriate-use indications accounted for 92% of all inappropriate tests. If all testing done for these five inappropriate reasons were to be eliminated, total imaging volume would be reduced by 12.4% (J. Am. Coll. Cardiol. 2010;55:156-62).

"Imaging in Focus" is an ACC-sponsored national quality improvement initiative aimed at helping cardiovascular physicians to reduce inappropriate imaging in a collaborative, nonconfrontational way through the use of webinars, blogs, and other tools. It’s designed as a learning community whose stated goal is to achieve a 50% reduction in inappropriate cardiovascular imaging in 3 years. Dr. Hendel announced some good news: The program has already resoundingly surpassed that target. In just its first year of operation, imaging centers participating in Imaging in Focus reduced their inappropriate imaging by 50% from a baseline rate of 10%.

"This is very exciting," he said.

None of the speakers had relevant financial interests.

DENVER – The majority of nuclear cardiology labs are not utilizing the American College of Cardiology appropriate use criteria for myocardial perfusion imaging, according to the preliminary results of an American Society of Nuclear Cardiology membership survey.

The revelation that only 48% of nuclear cardiology imaging labs employ the ACC appropriate use criteria is disturbing. It comes at a time when nuclear cardiologists are already drawing heat from payers, clinicians, patients, and Congress for perceived overutilization of testing and a casual attitude toward patient exposure to radiation.

The ACC’s appropriate use criteria (AUC) program is a high-profile quality improvement initiative. The myocardial perfusion imaging AUC were developed jointly by the ACC, ASNC, and other key specialty societies. Myocardial perfusion imaging (MPI) was the first topic selected for the program, which has since gone on to develop AUC for other common cardiovascular tests and procedures. MPI was selected to go first because of concerns raised by the explosive growth and substantial regional variation in the procedures. The initial version of the MPI AUC was published in 2005, with an updated rendition appearing 2 years ago (J. Am. Coll. Cardiol. 2009;53:2201-9).

ASNC President Leslee J. Shaw, Ph.D., presented the preliminary membership survey results during her presidential address at the annual meeting of the American Society of Nuclear Cardiology. She also took that occasion to unveil an ambitious new multifaceted ASNC campaign called "Excellence in Imaging." The program is designed to improve the practice of nuclear cardiology through education and advocacy, and by fostering high-quality research that demonstrates nuclear imaging’s clinical value. ASNC members who take the Excellence in Imaging pledge commit themselves to following the AUC.

"By taking a proactive stance on defining quality in nuclear cardiology and demonstrating our members’ commitment to these defined quality measures, ASNC will lead the discussion about appropriate use and set the standards by which our patients receive optimal care," promised Dr. Shaw, professor of medicine at Emory University, Atlanta.

"What the survey results say to me is that we need to do a better job of providing you with tools where you can see the value in improving your process of care, and how the AUC can be utilized to actually identify appropriate patient referral patterns and track your success. This is increasingly going to be a performance metric. Your rating for appropriate test candidates is going to be used as a quality metric," she explained.

The educational portion of the Excellence in Imaging campaign will not only include continuing medical education that is designed to raise the quality of imaging by ASNC members, but also webinars for referring physicians aimed at fostering appropriate referral patterns. Clinical decision support tools are being developed that can be embedded in smart phones to assist referring physicians in selecting the optimal test for a given patient, rather than leaving the testing decision to be made downstream when the patient arrives at the nuclear cardiology clinic. There will also be public education efforts to dispel widespread misconceptions about radiation safety.

Later, Dr. Manuel D. Cerqueira observed that shifting the timing of appropriate test decision making to the point when testing is ordered by referring physicians is "easy to say, hard to do."

No matter how many conversations he has with emergency department physicians at outlying hospitals about not sending him low-risk, inappropriate candidates for imaging procedures involving ionizing radiation exposure when there are better nonradioactive tests available, they continue to do so.

"They’re worried about liability, they’re worried about their 1-year contract that gets reviewed by the hospital, and they’re worried about the pressure the hospital puts on them to do more procedures that are lucrative for the hospital," said Dr. Cerqueira, professor of radiology and medicine and chairman of the nuclear medicine imaging institute at the Cleveland Clinic Foundation.

In a separate presentation, Dr. Robert C. Hendel, who chaired the writing group for the updated MPI AUC, said a dozen studies presented in the past 5 years demonstrate that 10%-15% of all MPIs are inappropriate, as defined by the AUC.

"Basically, if it’s an inappropriate indication, by definition the risks exceed the benefits. The best radiation safety we can do is not to perform the test – not to expose the patient – when it’s not necessary," explained Dr. Hendel, professor of medicine and radiology and director of cardiac imaging and outpatient services at the University of Miami.

He led a six-center study called SPECT-MPI involving roughly 6,000 consecutive patients who underwent single photon emission CT. Overall, inappropriate use of the procedure occurred in 14.4% of patients, with rates ranging from 4% to 22% among the practices.

The SPECT-MPI study identified the major problem areas for inappropriate utilization. Topping the list was the use of MPI to detect CAD in asymptomatic patients at low risk for coronary heart disease; this accounted for 45% of all inappropriate tests and 6% of total testing.

The five most common inappropriate-use indications accounted for 92% of all inappropriate tests. If all testing done for these five inappropriate reasons were to be eliminated, total imaging volume would be reduced by 12.4% (J. Am. Coll. Cardiol. 2010;55:156-62).

"Imaging in Focus" is an ACC-sponsored national quality improvement initiative aimed at helping cardiovascular physicians to reduce inappropriate imaging in a collaborative, nonconfrontational way through the use of webinars, blogs, and other tools. It’s designed as a learning community whose stated goal is to achieve a 50% reduction in inappropriate cardiovascular imaging in 3 years. Dr. Hendel announced some good news: The program has already resoundingly surpassed that target. In just its first year of operation, imaging centers participating in Imaging in Focus reduced their inappropriate imaging by 50% from a baseline rate of 10%.

"This is very exciting," he said.

None of the speakers had relevant financial interests.

DENVER – The majority of nuclear cardiology labs are not utilizing the American College of Cardiology appropriate use criteria for myocardial perfusion imaging, according to the preliminary results of an American Society of Nuclear Cardiology membership survey.

The revelation that only 48% of nuclear cardiology imaging labs employ the ACC appropriate use criteria is disturbing. It comes at a time when nuclear cardiologists are already drawing heat from payers, clinicians, patients, and Congress for perceived overutilization of testing and a casual attitude toward patient exposure to radiation.

The ACC’s appropriate use criteria (AUC) program is a high-profile quality improvement initiative. The myocardial perfusion imaging AUC were developed jointly by the ACC, ASNC, and other key specialty societies. Myocardial perfusion imaging (MPI) was the first topic selected for the program, which has since gone on to develop AUC for other common cardiovascular tests and procedures. MPI was selected to go first because of concerns raised by the explosive growth and substantial regional variation in the procedures. The initial version of the MPI AUC was published in 2005, with an updated rendition appearing 2 years ago (J. Am. Coll. Cardiol. 2009;53:2201-9).

ASNC President Leslee J. Shaw, Ph.D., presented the preliminary membership survey results during her presidential address at the annual meeting of the American Society of Nuclear Cardiology. She also took that occasion to unveil an ambitious new multifaceted ASNC campaign called "Excellence in Imaging." The program is designed to improve the practice of nuclear cardiology through education and advocacy, and by fostering high-quality research that demonstrates nuclear imaging’s clinical value. ASNC members who take the Excellence in Imaging pledge commit themselves to following the AUC.

"By taking a proactive stance on defining quality in nuclear cardiology and demonstrating our members’ commitment to these defined quality measures, ASNC will lead the discussion about appropriate use and set the standards by which our patients receive optimal care," promised Dr. Shaw, professor of medicine at Emory University, Atlanta.

"What the survey results say to me is that we need to do a better job of providing you with tools where you can see the value in improving your process of care, and how the AUC can be utilized to actually identify appropriate patient referral patterns and track your success. This is increasingly going to be a performance metric. Your rating for appropriate test candidates is going to be used as a quality metric," she explained.

The educational portion of the Excellence in Imaging campaign will not only include continuing medical education that is designed to raise the quality of imaging by ASNC members, but also webinars for referring physicians aimed at fostering appropriate referral patterns. Clinical decision support tools are being developed that can be embedded in smart phones to assist referring physicians in selecting the optimal test for a given patient, rather than leaving the testing decision to be made downstream when the patient arrives at the nuclear cardiology clinic. There will also be public education efforts to dispel widespread misconceptions about radiation safety.

Later, Dr. Manuel D. Cerqueira observed that shifting the timing of appropriate test decision making to the point when testing is ordered by referring physicians is "easy to say, hard to do."

No matter how many conversations he has with emergency department physicians at outlying hospitals about not sending him low-risk, inappropriate candidates for imaging procedures involving ionizing radiation exposure when there are better nonradioactive tests available, they continue to do so.

"They’re worried about liability, they’re worried about their 1-year contract that gets reviewed by the hospital, and they’re worried about the pressure the hospital puts on them to do more procedures that are lucrative for the hospital," said Dr. Cerqueira, professor of radiology and medicine and chairman of the nuclear medicine imaging institute at the Cleveland Clinic Foundation.

In a separate presentation, Dr. Robert C. Hendel, who chaired the writing group for the updated MPI AUC, said a dozen studies presented in the past 5 years demonstrate that 10%-15% of all MPIs are inappropriate, as defined by the AUC.

"Basically, if it’s an inappropriate indication, by definition the risks exceed the benefits. The best radiation safety we can do is not to perform the test – not to expose the patient – when it’s not necessary," explained Dr. Hendel, professor of medicine and radiology and director of cardiac imaging and outpatient services at the University of Miami.

He led a six-center study called SPECT-MPI involving roughly 6,000 consecutive patients who underwent single photon emission CT. Overall, inappropriate use of the procedure occurred in 14.4% of patients, with rates ranging from 4% to 22% among the practices.

The SPECT-MPI study identified the major problem areas for inappropriate utilization. Topping the list was the use of MPI to detect CAD in asymptomatic patients at low risk for coronary heart disease; this accounted for 45% of all inappropriate tests and 6% of total testing.

The five most common inappropriate-use indications accounted for 92% of all inappropriate tests. If all testing done for these five inappropriate reasons were to be eliminated, total imaging volume would be reduced by 12.4% (J. Am. Coll. Cardiol. 2010;55:156-62).

"Imaging in Focus" is an ACC-sponsored national quality improvement initiative aimed at helping cardiovascular physicians to reduce inappropriate imaging in a collaborative, nonconfrontational way through the use of webinars, blogs, and other tools. It’s designed as a learning community whose stated goal is to achieve a 50% reduction in inappropriate cardiovascular imaging in 3 years. Dr. Hendel announced some good news: The program has already resoundingly surpassed that target. In just its first year of operation, imaging centers participating in Imaging in Focus reduced their inappropriate imaging by 50% from a baseline rate of 10%.

"This is very exciting," he said.

None of the speakers had relevant financial interests.

DENVER – The presence of left anterior fascicular block on a resting ECG indicates an ECG exercise stress test will have significantly diminished diagnostic accuracy, according to a retrospective study.

Thus, this finding on the resting ECG warrants giving serious consideration to adding an imaging modality such as single-photon emission computed tomography (SPECT) myocardial perfusion imaging to the patient’s exercise stress test, Dr. Tarek M. Mousa said at the annual meeting of the American Society of Nuclear Cardiology.

He presented a retrospective study of 1,403 patients who underwent both a maximal treadmill exercise stress ECG test and SPECT myocardial perfusion imaging in search of inducible myocardial ischemia. In all, 62 patients (4.4%) had left anterior fascicular block (LAFB) on their resting ECG, including 24 who had both LAFB and right bundle branch block.

The exercise ECG stress test showed greatly reduced sensitivity for myocardial ischemia in patients with LAFB on their resting ECG: 39% as compared with 70% in the 1,341 patients without LAFB.

On the other hand, a finding of greater than 1 mm of exercise-induced ST-segment depression in at least two contiguous leads had significantly greater specificity as an indicator of inducible myocardial ischemia when it occurred in the setting of LAFB: 96% as compared with 79% in controls, added Dr. Mousa of New York Hospital Queens in Flushing.

The presence or absence of right bundle branch block in patients with LAFB on their resting ECG did not affect the diagnostic accuracy of their ECG exercise stress test.

Dr. Mousa declared having no financial conflicts.

DENVER – The presence of left anterior fascicular block on a resting ECG indicates an ECG exercise stress test will have significantly diminished diagnostic accuracy, according to a retrospective study.

Thus, this finding on the resting ECG warrants giving serious consideration to adding an imaging modality such as single-photon emission computed tomography (SPECT) myocardial perfusion imaging to the patient’s exercise stress test, Dr. Tarek M. Mousa said at the annual meeting of the American Society of Nuclear Cardiology.

He presented a retrospective study of 1,403 patients who underwent both a maximal treadmill exercise stress ECG test and SPECT myocardial perfusion imaging in search of inducible myocardial ischemia. In all, 62 patients (4.4%) had left anterior fascicular block (LAFB) on their resting ECG, including 24 who had both LAFB and right bundle branch block.

The exercise ECG stress test showed greatly reduced sensitivity for myocardial ischemia in patients with LAFB on their resting ECG: 39% as compared with 70% in the 1,341 patients without LAFB.

On the other hand, a finding of greater than 1 mm of exercise-induced ST-segment depression in at least two contiguous leads had significantly greater specificity as an indicator of inducible myocardial ischemia when it occurred in the setting of LAFB: 96% as compared with 79% in controls, added Dr. Mousa of New York Hospital Queens in Flushing.

The presence or absence of right bundle branch block in patients with LAFB on their resting ECG did not affect the diagnostic accuracy of their ECG exercise stress test.

Dr. Mousa declared having no financial conflicts.

DENVER – The presence of left anterior fascicular block on a resting ECG indicates an ECG exercise stress test will have significantly diminished diagnostic accuracy, according to a retrospective study.

Thus, this finding on the resting ECG warrants giving serious consideration to adding an imaging modality such as single-photon emission computed tomography (SPECT) myocardial perfusion imaging to the patient’s exercise stress test, Dr. Tarek M. Mousa said at the annual meeting of the American Society of Nuclear Cardiology.

He presented a retrospective study of 1,403 patients who underwent both a maximal treadmill exercise stress ECG test and SPECT myocardial perfusion imaging in search of inducible myocardial ischemia. In all, 62 patients (4.4%) had left anterior fascicular block (LAFB) on their resting ECG, including 24 who had both LAFB and right bundle branch block.

The exercise ECG stress test showed greatly reduced sensitivity for myocardial ischemia in patients with LAFB on their resting ECG: 39% as compared with 70% in the 1,341 patients without LAFB.

On the other hand, a finding of greater than 1 mm of exercise-induced ST-segment depression in at least two contiguous leads had significantly greater specificity as an indicator of inducible myocardial ischemia when it occurred in the setting of LAFB: 96% as compared with 79% in controls, added Dr. Mousa of New York Hospital Queens in Flushing.

The presence or absence of right bundle branch block in patients with LAFB on their resting ECG did not affect the diagnostic accuracy of their ECG exercise stress test.

Dr. Mousa declared having no financial conflicts.