FDA looks again at Boston Scientific anti-stroke device

U.S. Food and Drug Administration staff reviewing data on Boston Scientific Corp's novel anti-stroke device highlighted the implant's failure to meet a key goal for effectiveness in a recent study but said on Monday that other data must be weighed in deciding whether it should be approved.

The FDA released documents about the device, called Watchman, ahead of a meeting on Wednesday of outside medical experts who will consider its risks and benefits and then recommend whether the FDA should approve the product for use in patients.

The device, implanted on the heart to prevent stroke in patients with a dangerous cardiac rhythm known as atrial fibrillation, was developed as an alternative to clot-preventing blood thinners. If approved, it could spare heart patients a lifetime of taking anticoagulant drugs, such as warfarin, that carry a high risk of bleeding.

An FDA advisory panel in 2009 recommended approval of the first-of-its-kind device, but the agency ultimately decided another study was needed to evaluate its safety and effectiveness.

The second clinical trial, however, failed to meet a key goal showing the device to be as effective as warfarin in preventing stroke.

FDA staff on Monday said the expert panel will need to consider follow-up results from the first trial, data from a patient registry and the new study results in making its recommendations.

"It is critical that advisory panel members review the totality of the data in making these determinations as each component of the data set has strengths and limitations," the FDA reviewers said.

Wells Fargo analyst Larry Biegelsen said he believes the FDA will approve the device, but cautioned that Wednesday's meeting could be contentious. Key issues for the panel will be the missed goal in the newer study, as well as implications of new oral anti-coagulants on the market, he said.

"The FDA stresses a number of times in the briefing documents that the panel members should consider the totality of the data, which we think is a positive sign," Biegelsen said in a research report.

Boston Scientific acquired the Watchman device when it bought Atritech in March 2011. It has been on the market in Europe since 2005.

People with atrial fibrillation, the most common type of arrhythmia, are five times more likely to suffer a stroke than those without the condition. It affects nearly 3 million people in the United States and that number is expected to increase.