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CHICAGO -- Left atrial appendage closure with the Watchman device maintained good safety and efficacy at 1 year in patients largely not on oral anticoagulants, the EWOLUTION registry found.

The rate of ischemic stroke at 1 year was a "very low" 1.1% in the registry compared with the expected 7.2% based on the CHA₂DS₂-VASc score, while the combined rate of ischemic stroke, transient ischemic attack, or systemic embolism was 1.5% versus an expected 10.1% -- both more than 80% relative risk reductions.

Bleeding rates were roughly half those expected based on HAS-BLED risk scores at 1 year: 2.6% versus an expected 5.0% for major bleeding and 2.3% versus 5.0% expected for non-procedural major bleeding, Lucas Boersma, MD, PhD, of St. Antonius Hospital in Nieuwegein, the Netherlands, reported here at the Heart Rhythm Society (HRS) meeting.

And while 3.7% of the patients with transesophageal echocardiography follow-up (87% of the 1,020) had documented device thrombus "in line with prior trials," only one of these had a stroke by 1 year.

"Most of the work to date that we know come from randomized trials in patients tolerant to warfarin, and have used warfarin for a bridging therapy for at least 45 days," Boersma noted at an HRS press conference. "In Europe, this is not the population we're targeting. In Europe, guidelines tell us that we should reserve the therapy specifically for patients that are not tolerant of warfarin."

The FDA approval for Watchman specified use only for patients who would be suitable candidates for warfarin but who "have an appropriate rationale to seek a non-pharmacologic alternative to warfarin." Medicare reimbursement criteria require "suitability for short-term warfarin but deemed unable to take long term oral anticoagulation following the conclusion of shared decision making, as [left atrial appendage closure] is only covered as a second line therapy to oral anticoagulants."

In the registry of 1,020 Watchman recipients in Europe, Russia, and the Middle East, 73% had contraindications to warfarin use. Most of the participants were on single or dual antiplatelet therapy (84%) or no anticoagulation (9%)

The 1-year mortality rate in this population sicker than that of the clinical trials was 9.8%, of which most was from non-cardiovascular causes (rate 5.5%).

"This is excellent data that we need. These are the patients you want to treat with Watchman," commented HRS session co-chair Andrea Russo, MD, director of the Electrophysiology and Arrhythmia Service of Cooper University Hospital in Camden, N.J. "So now we can see you can do this in the patient population we would like to do this in."

However, the challenge for U.S. clinicians in implanting Watchman in patients unable to take warfarin is less regulatory or reimbursement than fear of litigation, suggested James Reiffel, MD, co-director of the Electrocardiography Lab at New York-Presbyterian Hospital/Columbia University Medical Center in New York City.

The situation is unlikely to change, Boersma suggested, until results emerge from the randomized comparison of Watchman versus single antiplatelet or no therapy in atrial fibrillation patients who can't take warfarin that is underway, the .

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