Analysts startled as Boston Scientific holds back Watchman data

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Boston Scientific is planning to present limited results from a study of Watchman.--Courtesy of Boston Scientific

Boston Scientific ($BSX) is slated to present late-breaking study data on its much-anticipated Watchman device, but now the company says it will only unveil some of the safety results, spurring analyst speculation that the stroke-prevention tech hasn't lived up to its hype.

The company is scheduled to discuss the results of its Prevail study at this weekend's American College of Cardiology meeting in San Francisco, Bloomberg reports, and Boston Scientific's announcement that it will hold back some of the data has led to an investigation by the college.

For its part, Boston Scientific told Bloomberg it is still evaluating Watchman's efficacy data to see if it will be ready for presentation on Saturday.

The news is alarming for analysts, who worry that Boston Scientific's sudden reticence could indicate that Watchman failed to reach one or more of Prevail's endpoints, meaning it may not offer the reduction in stroke rates the company has promised. Wells Fargo analyst Larry Biegelsen said in a note to investors that he wouldn't be surprised to see the company change its mind before Saturday, as backing out this late is highly unusual.

Boston Scientific has been steadily meting out data on Watchman, a left atrial appendage closure device inserted in the heart to capture blood clots and treat irregular heartbeats. The device is CE marked for both AF and stroke prevention in Europe, and Boston Scientific is deep in the PMA process to win FDA approval.

High expectations for Watchman are part of CEO Mike Mahoney's plan to reverse Boston Scientific's years of slumping sales, as he's counting on a slew of new devices and new indications for existing ones to drag the devicemaker into revenue growth for the first time since 2009.

- read Bloomberg's story

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