A device that closes the left atrial appendage to prevent stroke in patients with nonvalvular atrial fibrillation showed a 95.6% procedural success rate in a study of real-world experience since it was approved by the FDA in 2015, according to a report presented at the Transcatheter Cardiovascular Therapeutics annual meeting and published simultaneously in the Journal of the American College of Cardiology.

The study was based on data collected by Boston Scientific, the manufacturer of the Watchman device, regarding 3,822 consecutive patients who underwent the implantation during a 14-month period. The “excellent” procedural success rate, together with low short-term complication rates, are especially “remarkable” because 71% of the interventional cardiologists and electrophysiologists who performed these procedures had no experience with the device prior to FDA approval, said Vivek Y. Reddy, MD , of Mount Sinai Medical Center, New York.

Previous randomized controlled trials found that this left atrial appendage (LAA) closure device was noninferior to warfarin in preventing stroke or systemic embolism and superior in reducing hemorrhagic stroke, cardiovascular mortality, and bleeding events.

For this study, the implantations were done by 382 physicians at 169 U.S. medical centers. A total of 3,653 procedures were successful. The median duration of the implantation was “an acceptable” 50 minutes (range, 10-210 minutes), and an average of 1.38 devices (range, 1-6) were required per patient. In 23% of cases, a “partial recapture” of a device was necessary to reposition it (J Am Coll Cardiol. 2016 Nov. doi: 10.1016/j.jacc.2016.10.010).

The rates of major complications within 1 week – pericardial tamponade (<1%), procedure-related stroke (0.08%), and mortality (0.08%) – were characterized as “favorable.”

The most common complication was pericardial effusion requiring intervention, which developed in 39 patients (1.02%). The effusions were drained percutaneously in most (24) of these patients. Another 11 patients (0.29%) developed mild pericardial effusions requiring only conservative management.

Three strokes, two ischemic and one hemorrhagic, were deemed related to the procedure, though the hemorrhagic bleed may have resulted chiefly from anticoagulation medications. Three deaths were judged to be related to the procedure: All were secondary to pericardial tamponade associated with perforation by the device.

“It is worth comparing [this] cardiac tamponade rate with [that of] another left atrial cardiovascular procedure, catheter ablation of atrial fibrillation,” Dr. Reddy noted.

A worldwide survey of more than 20,000 catheter ablations reported a pericardial tamponade rate of 1.31%, and another study of more than 93,000 ablation procedures performed during a 1-year period reported a rate of 1.52%, he said at the meeting, which was sponsored by the Cardiovascular Research Foundation.

Other short-term complications in this study included nine cases of device embolization (0.24%). Six of these required surgical removal of the device, while three were retrieved percutaneously.

No sponsor was cited for this study. Boston Scientific, maker of the Watchman left atrial appendage closure device, collected the data on all implantations of the device in the United States following FDA approval. Dr. Reddy and his associates reported ties to Boston Scientific, Coherex, SentreHeart, Abbott Vascular, and St. Jude Medical.