The Watchman left atrial appendage (LAA) closure device has been approved in the United States as an alternative to warfarin for patients with nonvalvular atrial fibrillation, for a narrower indication than the one submitted for approval to the Food and Drug Administration.

The device is a percutaneously delivered permanent cardiac implant placed in the LAA to prevent the embolization of thrombi formed in the LAA, and is manufactured by Boston Scientific. The FDA approved the Watchman for reducing the risk of thromboembolism from the LAA in patients in patients with nonvalvular atrial fibrillation “who are at increased risk for stroke and systemic embolism based on CHADS2 or CHA2DS2-VASc scores, are deemed by their physicians to be suitable for warfarin; and have an appropriate rationale to seek a nonpharmacologic alternative to warfarin, taking into account the safety and effectiveness of the device, compared to warfarin,” according to a statement issued by the company on March 13.

The approved indication is worded differently than the proposed indication that was submitted to the FDA for approval and discussed at an FDA panel meeting in October, to “prevent thromboembolism from the left atrial appendage.” The changes in the indication include the replacement of “prevent” with “reduce the risk” of thromboembolism, and the addition of the following qualifiers: In patients who “are deemed by their physicians to be suitable for warfarin,” and who have “an appropriate rationale to seek a nonpharmacologic alternative to warfarin, taking into account the safety and effectiveness of the device compared to warfarin.”

“These changes were made to more accurately reflect the appropriate patient population for this device,” according to an FDA spokesperson.

At a meeting in October 2014, the FDA’s Circulatory System Devices Panel voted 6-5 with one abstention that the benefits of the device outweighed its risks for the proposed indication, but several panelists who voted no said they would support approval of a second-line indication. In addition, panelists voting on both sides of this question said that the indication was too broad and should be revised to describe the device as a second-line alternative to warfarin, making clear it is not appropriate for all warfarin-eligible patients. (At the meeting, the panel unanimously agreed that there was “reasonable assurance” that the device was safe for use in this population.)

At the first advisory panel meeting on the device, in December 2013, the panel voted 13-1 to recommend approval, based on data from the PREVAIL and PROTECT-AF studies, which compared the device to chronic warfarin, and information from the Continued Access to PREVAIL ( CAP2 ) registry.PREVAIL compared implantation of the device – with 45 days of warfarin plus 81 mg of aspirin for 45 days, followed by 325 mg of aspirin and 75 mg of clopidogrel through 6 months, followed by 325 mg of aspirin a day indefinitely – to chronic warfarin.

The October meeting was convened by the FDA to review longer follow-up data from PREVAIL, which found additional cases of ischemic strokes in the Watchman group and none in the warfarin-treated group.

The Watchman device has been available outside of the United States since 2009, is registered in 75 countries, and has been used to treat more than 10,000 patients, according to Boston Scientific.