New evidence largely confirms that occlusion of the left atrial appendage (LAA) with the transcatheter Watchman device is safe and provides ischemic stroke protection similar to warfarin therapy. This follows the publication of results from the PREVAIL trial in the July 8, 2014, issue of the Journal of the American College of Cardiology, a follow-up to the randomised PROTECT AF trial.

The device was successfully implanted in 95.1% of patients in whom it was attempted (252 of 265). In this group, 92.2% were able to discontinue warfarin at 45 days and 99.3% by 12 months. At 18 months, rates of the first primary efficacy endpoint (stroke, systemic embolism, and cardiovascular/unexplained death) were similar between the device and control groups, but the prespecified margin of noninferiority was not achieved. However, the rate of the late ischemic primary efficacy endpoint (stroke or systemic embolism more than 7 days after randomization) did meet the criterion for noninferiority.

In an accompanying editorial, Randall J. Lee, MD, PhD, of the Cardiovascular Research Institute and the department of medicine at the Institute for Regeneration Medicine at the University of California, San Francisco, said that the Watchman studies are the first to demonstrate that LAA occlusion may be useful in preventing stroke.

“On the basis of the efficacy data from the initial PROTECT AF trial, the improved mortality data of the 5-year follow-up from PROTECT AF, the improved safety results of the Continued Access PROTECT AF Registry, and the safety data from PREVAIL, an FDA panel recently voted 13 to 1 to approve the Watchman device for use in patients with [nonvalvular] AF,” Lee wrote. “Although the Watchman studies provide the proof of principle that LAA exclusion is effective in preventing stroke in patients with [nonvalvular] AF, LAA device implants should not be considered universally as a substitute for oral anticoagulation therapy.”