Washington, DC—A minimally invasive procedure thought to provide dramatic improvements in blood pressure for patients with resistant hypertension may not work or offers only modest improvement.
The procedure, renal denervation, involves the use of a steerable catheter with an electrode tip to deliver pulses of radiofrequency energy along each renal artery to deactivate renal sympathetic nerves, which can reduce blood pressure. Earlier and small studies of renal denervation found the procedure appeared to reduce systolic blood pressure by more than 30 mm Hg. The procedure is used in more than 80 countries, but it has not been approved in the United States.
Studies presented over the weekend at late-breaking clinical trials showcased at the Scientific Sessions of the American College of Cardiology should give proponents of the procedure pause.
On Saturday, researchers presented results from the SYMPLICITY HTN-3 trial. In this trial, 535 patients with resistant hypertension (systolic blood pressure of 140 mm Hg or higher despite taking 3 or more antihypertensive medications) were randomly assigned in a ratio of about 2 to 1 to receive renal angiography plus denervation or a sham procedure of renal angiography only. At 6 months, office-based systolic blood pressure dropped 14.13 mm Hg in the denervation group and 11.74 mm Hg in the sham group, a nonstatistical difference. For 24-hour ambulatory blood pressure, systolic pressure dropped 6.75 mm Hg in the denervation group and 4.79 mm Hg in the sham group, also a nonstatistical difference.
Findings presented on Sunday offered less pessimistic but still modest results for denervation proponents. For this study, researchers looked at 6-month results from the first 1000 patients enrolled in the Global SYMPLICITY Registry. The registry will ultimately enroll 5000 patients from 200 sites worldwide to assess the safety and efficacy of the procedure at 6 months. The investigators found that office systolic blood pressure readings dropped 11.9 mm Hg for all patients and 19.8 mm Hg for those with systolic pressures of 160 mm Hg or higher. For the ambulatory setting, systolic pressure dropped 7.9 mm Hg for patients with initial systolic blood pressure of 140 mm Hg or higher and 9.2 mm Hg for those with systolic pressures of 160 mm Hg or higher.
As for what these results mean for the procedure , renal denervation is “not dead,” said George Bakris, MD, a coauthor of SYMPLICTY HTN-3 trial and director of the Hypertensive Disease Center at the University of Chicago Medical Center. “These studies answered some question and raised others.”
Medtronic Inc, which sponsored both studies and whose SYMPLICITY renal denervation system was used in the study, said in a news release that it planned to continue providing the system in countries already with regulatory approval and will continue to seek approval in the United States.