Could Watchman® Results Mean FDA Approval Will Follow?

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In short

It’s the American College of Cardiology, annual “Sceintific Sessions” meeting in San Francisco this weekend. While the event is likely to be the usual action-packed affair, one device-related study is being presented that is sure to draw most attention: The Watchman Left Atrial Appendage (LAA) occlusion device vs long term Warfarin in the prevention of strokes.

Background 

We’ve covered Boston Scientific’s Watchman left atrial appendage closure device for some time, most recently last summer when it gained CE mark approval for use in patients unable to undergo warfarin or other anticoagulant therapy. Find that article here.

For the hitherto uninitiated, the Watchman device is intended to close off the LAA, this anatomical feature being the source of blood clots that can be associated with strokes. Watchman works by capturing any clots that may form in the appendage, reducing the risk of stroke and potentially eliminating the need for long term use of blood thinning medications. CE mark approval suggests the European authorities were happy that this was the case, but the FDA has been so far unconvinced and required further study evidence.

Around the same time as the new CE mark approval last August Boston Scientific announced that it had completed enrollment in the so-called PREVAIL clinical trial, which was to directly compare stroke prevention rates between Watchman and blood thinning therapy. Indeed the presentation is billed in the ACC meeting’s program as final results of the confirmatory safety and efficacy trial requested by the FDA when it turned down Atritech’s Watchman device in 2010.

The Watchman study is the focus of one of the ACC Scientific Sessions so-called “late breaking” clinical trial presentations. The study compared left atrial appendage closure with long-term warfarin (Coumadin) therapy for stroke prevention in patients with nonvalvular atrial fibrillation.

The company announced earlier this week that only the acute procedural safety results would be released at the meeting but reversed course yesterday, saying that, in fact, all three coprimary endpoints would be presented.

Either way, early safety of the device compared with warfarin is the key question, as the pivotal PROTECT HF showed equal efficacy between treatment arms but a 69% higher risk of bleeding and procedure-related complications with left atrial appendage closure.

Physician comments

The promise of device-based stroke prophylaxis centers on circumventing the bleeding risk that anticoagulation brings, conference chair Miguel Quiñones, MD, chief of cardiology at Methodist DeBakey Heart Center in Houston, explained at a pre-meeting press briefing.

“If in fact this trial does show positive results, the impact could be quite striking,” he said.

Source: Medpage today