December 12th, 2013

FDA Panel Gives Support to Left Atrial Appendage Closure Device

The FDA’s Circulatory System Devices Panel yesterday gave a vote of confidence to Boston Scientific’s Watchman left atrial appendage closure device for the prevention of stroke in atrial fibrillation patients. By a large majority, the panel agreed that the device was effective, that it was safe, and that the benefits outweighed the risks. In each case the vote was 13-1.

The panel decision may herald a change in fortune for the device, which has had a long and difficult history. In 2010, the FDA issued a complete response letter and earlier this year a scandal broke out when the American College of Cardiology cancelled a prestigious late-breaking clinical trial presentation of the PREVAIL trial after the company broke an embargo by giving trial results to investors.

The FDA is expected to make a decision whether to allow the Watchman to enter the U.S. market in the second half of 2014. Approval now seems likely, but the lopsided voting may not provide a full indication of lingering concerns about the device by panel members. Committee discussions focused on the data from two randomized control trials, PROTECT AF and PREVAIL, and from the continued access protocol registry.

During the long session on Wednesday, panelists repeatedly expressed concern about the potential for overuse of the device. Although panel members generally agreed that the Watchman was equivalent to standard treatment  with warfarin, they acknowledged that the data to support this view was difficult to interpret. In addition, they noted that the device has not been compared with the newer oral anticoagulants which have begun to replace warfarin as initial therapy in some patients. The FDA is likely to take these concerns into account when developing the  label for the device.

Rick Lange, who was the sole panel member to vote against approval, offered the following comment:

Despite the “warts” of the PROTECT AF trial, the panel thought that the totality of the data (including followup of 5 years) showed that the Watchman left atrial occluder device was non-inferior to warfarin therapy. I was the lone dissenter, voting against approval because the PREVAIL trial, which was designed to address the shortcomings of PROTECT AF, had collected endpoint data on only 28% of their patients. As a result, I didn’t think we had sufficient information to determine if the Watchman device was noninferior to warfarin therapy. Regardless, the entire panel was concerned that the device would be overused, and that patients would not be sufficiently informed that its use is not associated with a lower risk of major bleeding or ischemic stroke than warfarin therapy.”


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