Radiofrequency renal denervation provided progressive reductions in blood pressure at 3 years in patients on antihypertensive medication, but this did not translate into fewer antihypertensive drugs, new results from the SPYRAL HTN-ON MED trial show.
At 36 months, 24-hour ambulatory systolic and diastolic blood pressures were 10.0 mm Hg (P = .003) and 5.9 mm Hg (P = .005) lower, respectively, in patients who underwent renal denervation with Medtronic’s Symplicity Spyral radiofrequency catheter, compared with patients treated with a sham procedure.
The number of antihypertensive drugs, however, increased in both groups from an average of two at baseline and 6 months to three at 3 years (P = .76).
Based on the number of drugs, class, and dose, medication burden increased significantly in the sham group at 12 months (6.5 vs. 4.9; P = .04) and trended higher at 3 years (10.3 vs. 7.6; P = .26).
The procedure appeared safe, with no renal safety events in the denervation group and only three safety events overall at 36 months. One cardiovascular death occurred 693 days after a sham procedure and one patient had a hypertensive crisis and stroke 427 days after renal denervation and was discharged in stable condition, according to results published in The Lancet.
“Given the long-term safety and efficacy of renal denervation, it may provide an alternative adjunctive treatment modality in the management of hypertension,” Felix Mahfoud, MD, Saarland University Hospital, Homburg, Germany, said during a presentation of the study at the recent American College of Cardiology (ACC) 2022 Scientific Session.
The results are specific to the Symplicity Spyral catheter, which is investigational in the United States and may not be generalizable to other renal denervation devices, he added.
“The fact you have been able to accomplish this really is quite a feat,” said discussant Martin Leon, MD, New York-Presbyterian/Columbia University Irving Medical Center. “I would argue that the results at 36 months are at least as important as the ones at 6 months.”
He observed that one of the promises of renal denervation, however, is that it would be able to reduce patients’ drug burden with fewer drugs and lesser doses.
“At least in this trial, there was very little effect in terms of significantly reducing the pharmacologic burden,” Dr. Leon said. “So, it would be difficult for me to be able to say to patients that receiving renal denervation will reduce the number of medications you would need to treat. In fact, it increased from two to three drugs over the course of follow-up.”
The objective of the trial was not to reduce medication burden but to get blood pressure (BP) controlled in patients with an average baseline office reading of 164.4/99.5 mm Hg, Dr. Mahfoud replied. “We have shown that office systolic blood pressure decreased by around 20 millimeters of mercury in combination with drugs, so it may be seen as an alternative to antihypertensive medication in patients who are in need of getting blood pressure control.”
Dr. Leon responded that the BP control differences are “very dramatic and certainly very important” but that the word adjunctive can be tricky. “I’m trying to understand if it’s the independent or isolated effect of the renal denervation or if it’s a sensitivity to the biological or physiologic milieux which enhances the efficacy of the adjunctive drugs, especially with the fact that over time, it looked like you had increasing effects at some distance from the initial index procedure.”
Dr. Mahfoud said that previous work has shown that renal denervation reduces plasma renin activity and aldosterone concentrations. “It’s not fully understood, but I guess there are synergistic effects of denervation in combination with drugs.”