Boston Scientific's Watchman Faces Surgical Risk Question

Boston Scientific Corp. (BSX)’s Watchman device to prevent strokes may face a contentious regulatory meeting this week after a U.S. report showed the surgery required to implant the product may reduce its effectiveness.

The Watchman implant failed in a new trial to block clots in the heart’s left atrial appendage from causing a stroke as well as the current standard treatment that uses the blood-thinner warfarin, Food and Drug Administration staff said in a report today. Advisers to the agency are scheduled to meet Dec. 11 to weigh Watchman’s risks and benefits.

The FDA requested a new Watchman trial in 2010 after an initial study showed a high rate of complications. While one of the endpoints wasn’t met, the device did reach a second study goal of working as well as warfarin at preventing stroke if the initial surgical risks in the first seven days are excluded from consideration, according to the report.

“The FDA documents were more mixed than we anticipated which leads us to believe that the panel will be contentious but we still expect a positive outcome and approval,” Larry Biegelsen, an analyst at Wells Fargo & Co. in New York, wrote in a note to clients.

Boston Scientific fell less than 1 percent to $11.83 at 9:34 a.m. New York time. The shares of the Natick, Massachusetts-based company had more than doubled this year through Dec. 6.

$400 Million Market

The market for devices to close the left atrial appendage may total $400 million, and Watchman may generate $162 million in worldwide sales in 2017, Biegelsen wrote. Other stroke prevention in the U.S. comes from drugs including warfarin and new anticoagulants such as Eliquis from Bristol-Myers Squibb Co. and Pfizer Inc.

St. Jude Medical Inc. (STJ) is researching a a device similar to Watchman. Both the St. Jude and Boston Scientific products are already approved in Europe. The FDA probably will approve Boston Scientific’s Watchman in the second quarter of next year and St. Jude’s Amplatzer Cardiac Plug may reach the U.S. market in 2017, Biegelsen said.

Watchman is threaded into the heart then opens, resembling a parachute made of permeable polyester fabric to block the left atrial appendage. About 90 percent of stroke-causing clots start in the appendage, according to Columbia University’s Center for Interventional Vascular Therapy.

Boston Scientific is seeking approval of Watchman for patients who are eligible for warfarin therapy. People who have certain blood disorders or a tendency to hemorrhage shouldn’t take warfarin.

To contact the reporter on this story: Anna Edney in Washington at aedney@bloomberg.net

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net

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