An advisory panel to the FDA voted in favor of approval of the Watchman Left Atrial Appendage Closure device as an alternative to warfarin for people with atrial fibrillation who are at risk of strokes.

Members of the Circulatory System Devices Panel voted 13-1 in favor for benefits vs. risk, safety and efficacy after a review of two clinical trials, PROTECT AF and PREVAIL. The Watchman is a fabric-covered, self-expanding device that fits over the appendage opening and is permanently implanted or placed to prevent blood flow and clots from exiting the left atrial appendage and causing a stroke.

In April 2009, an FDA panel voted 7 to 5 to approve the Watchman “with conditions.” The panel noted the positive short-term data of the device during PROTECT AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients with Atrial Fibrillation), in which the Watchman reduced the risk of stroke, cardiovascular death and embolism in patients by 30 percent at 27 months of follow-up. The panel questioned the lack of long-term evidence, though. 

Four-year results from PROTECT-AF, presented at the 2013 Heart Rhythm Society scientific session, showed that the device was superior to warfarin for all-cause and cardiovascular death and for hemorrhagic stroke in patients with nonvalvular atrial fibrillation. The multicenter study assessed the safety and efficacy of the Watchman device. Warfarin, which is standard care, is an anticoagulant that interacts with other drugs and food and therefore requires monitoring.

The primary efficacy event rate was 2.3 percent in the Watchman group and 3.8 percent in the warfarin group. In secondary analyses, the device achieved superiority over warfarin for all-cause mortality (3.2 percent vs. 4.9 percent, for a 34 percent relative risk reduction) and for cardiovascular mortality (2.4 percent vs. 3.7 percent, for a 60 percent relative risk reduction).

Earlier results had shown the device to be noninferior to warfarin.

PREVAIL met with controversy at the 2013 American College of Cardiology scientific session when the sponsor, Boston Scientific, broke an embargo on the late-breaking clinical trial. PREVAIL compared Watchman to long-term warfarin therapy in patients with atrial fibrillation who are at risk for stroke.

The trial already was in the spotlight after Boston Scientific announced that the presentation would provide acute procedural safety results and not the complete results. The study met two of its three primary endpoints. There was a reduction in hemorrhagic stroke compared with warfarin but an increase in perioperative events.

The FDA is expected to make a decision on Watchman in the first half of 2014, Natick, Mass.-based Boston Scientific announced. The agency usually, but not always, follows the advice of its panel in approval decisions.