Boston Scientific: Watchman beats warfarin in follow-up

Boston Scientific's Watchman proved more effective than warfarin in a follow-up study.--Courtesy of Boston Scientific

Boston Scientific's ($BSX) Watchman is more effective at preventing stroke than standard-of-care warfarin, according to a study, giving the company some renewed hope for the device's FDA approval and eventual large market leadership.

Watchman, an implant designed to prevent strokes in atrial fibrillation patients, was statistically superior to the blood-thinning drug at preventing cardiovascular death, all-cause stroke and systemic embolization, according to four-year follow-up data from the Protect AF trial. The device works to close off the left atrial appendage, catching blood clots before they can flow up to the brain and cause strokes.

Coupled with an earlier study establishing the device's improved safety, the results could help Watchman win FDA approval, giving Boston Scientific a much-needed sales boost and putting an end to what has dragged on into a multi-year saga for Watchman. 

In 2010, the FDA sent Watchman back to the drawing board, unsatisfied with the high rate of complications in implanting the device. Boston Scientific then launched the Prevail study, aimed to demonstrate a lower rate of device-related injuries. Back in March, at the American College of Cardiology meeting, Boston Scientific demonstrated that it had done just that, but, in those same data, the company revealed that Watchman performed just about equal to warfarin, missing the study's second endpoint.

Now, with Prevail showing improved safety and Protect AF demonstrating superiority, Boston Scientific figures it has a better shot of winning over the FDA. 

"This is a significant development because for the first time we were able to demonstrate that the Watchman device was superior to warfarin for both primary efficacy and also mortality," principal investigator Vivek Reddy said in a statement. "The four-year data provide additional support for (left atrial appendage) closure as a potential viable long-term alternative to chronic warfarin therapy for patients to reduce the risk of stroke."

The company estimates the market for Watchman at about $500 million a year, and if it wins FDA approval, the device would be the only product of its kind on the market in the U.S. Wells Fargo analyst Larry Biegelsen said in a note to investors that Watchman could rake in annual sales of about $159 million by 2017.

Watchman is a pillar of Boston Scientific's turnaround strategy, as the company is counting on new devices and expanded indications in high-growth spaces to shepherd it back to revenue growth. Last quarter, the company reported a $354 million net loss as revenue slipped 6% to $1.761 billion.

- read the statement

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