A phase III pivotal trial has yielded mixed results for an experimental implantable device that uses baroreflex activation therapy (BAT) to treat resistant hypertension. The paper on the Rheos Pivotal Trial by John Bisognano and colleagues has been published online in the Journal of the American College of Cardiology.
265 patients with resistant hypertension had the Rheos device implanted. After 1 month they were then randomized on a 2:1 basis to have the device activated immediately (Group A) or after 6 months (Group B). There were 5 coprimary endpoints. The trial demonstrated sustained efficacy, BAT safety, and device safety, but was not successful in meeting the endpoints for acute systolic blood pressure (SBP) response or procedural safety:
- The acute SBP responder rate at 6 months was 54% for group A versus 46% in Group B (p=0.97), thereby not meeting the 20% superiority margin.
- The sustained responder rate at 12 months, 88% (p<0.001), met predefined criteria.
- Procedural safety: The procedure-related event-free rate of 74.8% did not meet the pre-specified performance criterion of 82%.
- BAT safety: The therapy-related event-free rate between 30 days and 6 months was 91.7% in Group A and 89.3% in Group B (p<0.001), which was within the noninferiority margin.
- Device safety: The event-free rate of 87.2% exceeded the pre-specified performance criterion of 72%.
In their discussion the authors acknowledge that the trial failed to meet all its endpoints but point out that the device produced significant reductions in SBP at 12 months and that more than half of the subjects reached a SBP of 140 mm Hg or lower. They write that the manufacturer has developed a less invasive implant procedure for delivering BAT that will be tested in future trials.