SYMPLICITY HTN-3 follow-up supports radiofrequency renal denervation for uncontrolled BP
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BOSTON — Radiofrequency renal denervation for uncontrolled hypertension appeared to demonstrate durable BP reduction out to 3 years in the setting of maximal antihypertensive therapy, a speaker reported.
The results of the long-term and final follow-up of the SYMPLICITY HTN-3 trial of radiofrequency renal denervation for resistant hypertension using a first-generation catheter (Symplicity Flex, Medtronic) were presented at TCT 2022 and simultaneously published in The Lancet.
“In this final follow-up from the SIMPLICITY HTN-3 trial, the largest and longest randomized clinical trial of renal denervation to date, we've demonstrated that renal denervation was safe through long-term follow-up, with no late emerging complications,” Cardiology Today Intervention Section Editor Deepak L. Bhatt, MD, MPH, executive director of interventional cardiology programs at Brigham and Women’s Hospital and professor of medicine at Harvard Medical School, said during a press conference. “Despite potential confounding factors, significant reductions were seen after denervation vs. control in office and ambulatory blood pressure out to 3 years, independent of medications.”
The sham-controlled SYMPLICITY HTN-3 trial enrolled 364 patients with uncontrolled hypertension to undergo radiofrequency renal denervation and compared in-office BP changes at 6 months with that of 171 patients who underwent a sham procedure.
Resistant hypertension was defined as in-office systolic BP of 160 mm Hg or more and 24-hour ambulatory systolic BP of 135 mm Hg. All participants were taking at least 3 antihypertensive medications at enrollment.
As Healio previously reported, the SYMPLICITY HTN-3 trial initially met its primary safety endpoint, but missed its primary efficacy endpoint — change in office systolic BP at 6 months — with no significant difference between denervation and sham groups (-14.13 vs. -11.74 mm Hg; P for difference = .26).
The present trial assessed the long-term outcomes among participants in the denervation arm who were followed out to 5 years. Those in the sham arm were followed out to 4 years.
At baseline, participants in the trial were taking on average 10 antihypertensive medication doses per day. By 3 years, the average daily doses were reduced to around eight per day for the denervation arm (P = .005), while the sham arm remained relatively unchanged. The average number of antihypertensive drug classes being taken by either arm also remained unchanged.
At baseline, 41.5% of patients in the denervation arm had systolic BP more than 180 mm Hg and 58.5% had systolic BP between 160 mm Hg and 180 mm Hg.
At 36 months, participants in the denervation arm had a mean difference in systolic BP of –22.1 mm Hg compared with sham (P < .0001). The reduction in office systolic BP observed in the denervation arm was stable out to 4 years (mean difference from baseline, –31.9 mm Hg) and 5 years (mean difference from baseline, –30.9 mm Hg). Bhatt explained that although changes in systolic BP due to denervation appeared durable over time, there were not enough participants left in the sham arm at 5 years to do a proper analysis.
At 3 years, participants in the denervation arm had a mean difference in 24-hour ambulatory systolic BP of –16.5 mm Hg compared with sham (P < .0001). The reduction in 24-hour ambulatory systolic BP also appeared durable out to 4 years (mean difference from baseline, –16.3 mm Hg); however, too few patients in the sham arm remained for Bhatt and colleagues to conduct a proper analysis.
“There was still an indication that there is no attenuation of the renal denervation effect. If anything, [there is] even a suggestion of a magnification of effect,” Bhatt said during the press conference.
After 6 months, a crossover group of 101 patients initially assigned to sham also underwent renal denervation. At baseline, 45.5% of patients in the sham arm had systolic BP more than 180 mm Hg and 54.5% had systolic BP between 160 and 180 mm Hg.
At 36 months after denervation, the proportion of crossover participants with systolic BP more than 180 mm Hg decreased to 28.6% and the proportion with systolic BP between 160 and 180 mm Hg decreased to 12.7%.
“These findings support that durable blood pressure reductions with radiofrequency renal denervation in the presence of maximum medical therapy are safely achievable,” Bhatt said during the press conference.
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[SYMPLICITY HTN-3] was a negative study, what they tried to do is say there is some durability when you are using renal denervation as an adjunct to medical management of these patients. Is there going to be a positive outcome or a durability of the results? I think it seemed like there is.
There is a lot more going on with the new catheters. We just have to say what we learned is that most likely renal denervation is coming back as an adjunct to medical management. But we'll see once it gets approved, it's not the be-all and end-all.
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Bhatt DL, et al. Late-Breaking Clinical Science in Vascular Disease and Hypertension: Session III, in Collaboration With the Journal of the American Medical Association. Presented at: TCT Scientific Symposium; Sept. 16-19, 2022; Boston (hybrid meeting).
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