HRS: Watchman bumps out warfarin in PROTECT AF

The Watchman wait may be over. An analysis of long-term data found the Watchman left atrial appendage closure device to be superior to warfarin for primary efficacy and mortality.

“There was an approximately 60 percent decrease in cardiovascular death in the Watchman group compared to the control group, which was statistically significant,” said Vivek Y. Reddy, MD, of the Cardiovascular Institute at Mount Sinai School of Medicine in New York City, on May 9 at a press conference at the Heart Rhythm Society scientific session in Denver. “There was also an 85 percent decrease in hemorrhagic stroke in the Watchman group compared to the control group, which was also statistically significant.”

Reddy presented the four-year results of PROTECT AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients with Atrial Fibrillation), a multicenter, prospective randomized clinical trial designed to assess the safety and efficacy of the Watchman device (Boston Scientific). The study compared the left atrial appendage (LAA) closure device with warfarin in patients with nonvalvular atrial fibrillation who are at risk of stroke. The device is designed to close off the LAA, where blood can pool and form clots. Warfarin, which is standard care, is an anticoagulant that interacts with other drugs and food and therefore requires monitoring.

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

The current analysis included 800 patients randomized 2:1 to the Watchman device or warfarin. The primary efficacy endpoint was a composite of stroke, systemic embolism and cardiovascular death. Patients in the Watchman group had an average CHADS2 score of 2.2 and patients in the warfarin group had an average score of 2.3. They were followed for a mean of 45 months.

The primary efficacy event rate was 2.3 percent in the Watchman group and 3.8 percent in the warfarin group. “For the first time, it was statistically superior,” Reddy said. The superiority primarily was driven by the reductions in cardiovascular deaths and hemorrhagic stroke.

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).

“I was not expecting that 34 percent decrease in all-cause mortality,” Reddy admitted.

A related Watchman trial, PREVAIL, came under fire at the American College of Cardiology’s scientific session in March after Boston Scientific broke the embargo on the late-breaking clinical trial. Drama already had mounted when the company flip-flopped over presenting all co-primary endpoints.

The Watchman device has been approved in Europe but remains an investigational device in the U.S. When asked if the superiority findings might persuade the FDA to approve the device, Reddy said, “It could happen but … the FDA is difficult to predict.”

PROTECT AF is funded by Atritech, which was acquired by Boston Scientific in 2011.