March 29, 2020
Three-Month Renal Denervation Outcomes Reported From SPYRAL-HTN OFF MED Pivotal Trial
March 29, 2020—The American College of Cardiology (ACC) announced that results from the SPYRAL-HTN OFF MED pivotal trial were presented by Michael Böhm, MD, at the virtual conference of the ACC’s Annual Scientific Session Together with World Congress of Cardiology (ACC.20/WCC).
The SPYRAL-HTN OFF MED data showed that 3 months after undergoing renal denervation (RDN) patients with untreated high blood pressure had statistically significant reductions in average blood pressure over 24 hours compared with patients who underwent a sham procedure, and that patients experienced no major adverse effects.
Dr. Böhm commented in the ACC press release, “These results show that RDN offers an effective alternative approach to traditional medications that require patient adherence for reducing blood pressure. 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.”
The SPYRAL-HTN OFF MED pivotal trial was designed in collaboration with the FDA to provide statistically significant evidence of whether RDN could reduce blood pressure in patients not taking blood pressure-reducing medication. The study was funded by Medtronic.
As summarized in the ACC announcement, the study was conducted at 46 sites in nine countries (the United States, Germany, Greece, Australia, Canada, Japan, the United Kingdom, Austria, and Ireland), enrolled 331 patients whose average systolic blood pressure (SBP) over 24 hours was between 140 and 170 mm Hg. The patients' average age was 53 years and 67% were men. Most had obesity, with an average body mass index of 31. Approximately 5% also had type 2 diabetes. A condition of enrollment was that patients either had not been taking any blood pressure-reducing medications or had discontinued those medications at least 3 weeks before their blood pressure was measured at study entry.
Patients were randomly assigned to receive either RDN or a sham procedure in which a catheter was inserted and only angiography was performed. A total of 166 patients were assigned to RDN and 165 to the sham procedure. Patients did not know whether they were receiving RDN or the sham procedure. The doctors and nurses who measured patients’ blood pressure and treated them after the procedure also did not know which group patients were in.
At 3 months, the primary efficacy endpoint was the change in average 24-hour SBP, adjusted for SBP at study entry. The secondary efficacy endpoint was the change in average blood pressure measured in the doctor’s office at 3 months, adjusted for office blood pressure at study entry. Major adverse safety events were also assessed at 3 months, including rates of death, stroke, changes in kidney function, or any injury to the arteries surrounding the kidney.
For the primary and secondary efficacy endpoints, the difference between groups was –3.9 mm Hg for 24-hour SBP and –6.5 mm Hg for office SBP, both favoring the RDN group, with a 99.9% probability that RDN was superior to the sham procedure. No deaths, strokes, or changes in kidney function occurred during the 3-month follow-up period.
Dr. Böhm added that these results may not demonstrate the total decrease in blood pressure achieved with RDN given the short follow-up period due to ethical and safety concerns that patients needed to be restarted on antihypertensive medications. In other studies of RDN, however, patients’ blood pressure has continued to decline at 6 months or more after the procedure, he said.
“This study establishes RDN as an additional option beyond exercise or lifestyle modification for patients with high blood pressure who are unwilling to take or cannot tolerate medication,” stated Dr. Böhm in the press release, adding that the study results will be included in an application for FDA approval of the RDN device used in the trial for the treatment of patients who are not taking blood pressure-reducing medication. Currently, there are no RDN devices approved for use in the United States, noted the ACC.
Results from a companion study, the SPYRAL-HTN ON MED trial, which is testing the safety and effectiveness of RDN in patients who are taking up to three blood pressure-reducing medications, are expected in approximately 18 months. The results of that study will also be included in the application for FDA approval of the RDN device, advised Dr. Böhm.