Boston Scientific’s Stroke Device Shows Mixed Results

Boston Scientific Corp.’s Watchman, designed to help prevent strokes in patients with an erratic heartbeat, may be a tougher sell for U.S. regulators after a study failed to confirm the device’s benefit.

The trial presented at the American College of Cardiology meeting in San Francisco two days ago found the Watchman could be used more safely than previous research. An initial analysis of the benefit, however, yielded mixed results. It wasn’t as good as the blood thinner warfarin at preventing clots, strokes and deaths in one of three primary analyses of the results.

The results make the device’s future less clear, said Raj Denhoy, an analyst at Jefferies & Co. in New York, in a note to clients. Boston Scientific officials have estimated a $500 million potential market within five years for devices used to prevent strokes by closing off a reservoir in the heart where blood pools and forms clots known as the left atrial appendage.

“The statistics remain complex and at this point it is unclear whether the data is sufficient to justify” U.S. Food and Drug Administration approval, Denhoy wrote. While the study “moved the Watchman device forward in terms of improved safety, showing improvements in every category, there remain basic questions on the design of the trial and whether the clinical benefit of the product has been proven,” he said.

St. Jude Competition

The Watchman competes against St. Jude Medical Inc.’s Amplatzer cardiac plug in Europe, where both are approved. St. Jude, based in St. Paul, Minnesota, said it started a study of the Amplatzer plug last week that will be used to try to obtain U.S. approval.

Boston Scientific rose less than 1 percent to $7.50 at the close in New York. St. Jude increased 1.1 percent to $42.70.

The FDA requested the new Watchman trial in 2009 after refusing to approve the device because the initial study showed an unacceptably high rate of complications. The new study dubbed Prevail involved 252 patients treated with the Watchman and 138 who were given the blood thinner warfarin as a comparison. Just 58 patients who received the device and 30 patients in the control group getting warfarin had completed the 18-month trial.

Boston Scientific plans to submit the findings, plus updated results from its initial Protect AF trial and other research, to the U.S. regulators to support Watchman’s approval, said Ken Stein, chief medical officer of the company’s cardiac rhythm management group.

The device probably will undergo a review at the FDA in the second half of the year, said Glenn Novarro, an analyst at RBC Capital Markets in New York.

“We peg the odds of approval at 50/50,” Novarro wrote in a note to clients. “Moreover, the Prevail results will likely reduce the positive sentiment surrounding Boston Scientific’s pipeline,” he wrote.