Shaped like a tiny umbrella, the device is preloaded into a catheter and implanted into the opening of a small pouch in the heart where it catches blood clots.


Boston Scientific speaks
Dr. Vivek Reddy, director of cardiac arrhythmia service at Mount Sinai Medical Center and coordinating investigator for this study, admitted that the trial endpoint was not as good as Boston Scientific would have liked.

But he also pointed out that the follow-up time for this study was short compared to the 2010 Protect trial, which had stronger efficacy results. Protect data followed patients for a combined total of 900 patient years, while Prevail data only studied a combined total of 380.

"We're looking at the data very early. If we looked at the Protect data at 380 patient years, it would look even worse than what we saw in Prevail," Reddy said.

What further complicates analysis of this study is that while the trial followed all the patients in the trial for six months, only 30 of 138 control patients and 58 of 269 device patients were followed for 18 months — a relatively small sample size.

Though the study was seen as a final hoop to jump through before the device received FDA approval, the fate of the device remains unclear for now.

Some experts speculate that the mixed results of the study may spur the FDA to ask for further studies, or approve the device only with a very restricted indication.

"We're very confident that we have the clinical data set to argue for approval with the FDA," said Joe Fitzgerald, president of cardiac rhythm management at Boston Scientific, though he did not elaborate whether the company aims for wider or restricted release.

The device, already available in 40 countries, was manufactured by Atritech, acquired by Boston Scientific in 2011.

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