Three months after undergoing renal denervation (RDN), patients with untreated high blood pressure (BP) had statistically significant reductions in average BP over 24 hours compared with patients who underwent a sham procedure and experienced no major adverse effects, according to results of the late-breaking SPYRAL-HTN OFF MED study presented March 29 during ACC.20/WCC and simultaneously published in The Lancet.

The SPYRAL-HTN OFF MED trial was designed in collaboration with the U.S. Food and Drug Administration (FDA) to obtain statistically significant evidence of whether RDN performed with the Symplicity Spyral catheter could reduce BP in patients not taking antihypertensive medication.

The study was conducted at 46 sites in nine countries and enrolled 331 patients whose average systolic blood pressure (SBP) over 24 hours was between 140 and 170 mm Hg. Their average age was 53 years and 67% were men. Most had obesity, with an average body mass index of 31, and around 5% had type 2 diabetes.

Patients who had not been taking any blood pressure-lowering medications or had discontinued those medications at least three weeks before their BP was measured at entry were randomized to RDN (n=166) or a sham procedure (n=165) in which a catheter was inserted and only an angiography was performed. The study was double-blind.

At three months, in the RDN and sham groups respectively, the primary efficacy endpoint of change in average 24-hour SBP, adjusted for SBP at study entry, was –3.9 mm Hg lower, and the secondary efficacy endpoint of change in average office BP, adjusted for office blood pressure at study entry, was –6.5 mm Hg lower, with a 99.9% probability that RDN was superior to the sham procedure.

There were no deaths, strokes or changes in renal function during the three-month follow-up period.

The researchers note these results may not demonstrate the total BP reduction achieved with RDN given the short follow-up period due to ethical and safety concerns that patients needed to be restarted on antihypertensive medications. Other studies of RDN have shown that BP continues to decline at six months or more after the procedure.

"These results show that RDN offers an effective alternative approach to traditional medications that require patient adherence for reducing blood pressure," says Michael Böhm, MD, lead author of the study. "Furthermore, the findings show that RDN lowers blood pressure not just during the day but also throughout the night and early-morning periods when risk is highest for [adverse] clinical events and the effect of some medications on blood pressure is reduced."

A companion study, the SPYRAL-HTN ON MED trial, testing the safety and effectiveness of RDN in patients who are taking up to three antihypertensive agents, is expected to conclude in about 18 months. The results of both studies will be included in an application to the FDA for approval of the Spyral catheter in this population. Currently there are no approved RDN devices in the U.S.

Clinical Topics: Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Prevention, Acute Heart Failure, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: ACC Annual Scientific Session, acc20, Blood Pressure, Antihypertensive Agents, Angiography, Primary Prevention, Heart Failure

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