New data from a clinical trial of Boston Scientific‘s (NYSE:BSX) Watchman anti-stroke device, presented last week at the annual Transcatheter Cardiovascular Therapies conference, showed no efficacy benefit in reducing the risk of stroke compared with the anti-coagulant warfarin
The Watchman device is scheduled for a 3rd appearance before the FDA’s Circulatory System Devices advisory panel Oct. 8, when the panel will consider the new data.
The panel has voted twice to approve the device, which is designed to reduce the risk of stroke by closing off the heart’s left atrial appendage, but the FDA has yet to make a final decision on Boston Scientific’s pre-market approval bid.
Watchman was initially rejected by FDA in 2009, because of a high rate of complications in an earlier trial. Initial results from a 2nd trial, the Prevail study, missed its efficacy endpoints.
Presenting last week at TCT, Dr. David Holmes of the Mayo Clinic said the 400-patient Prevail study found treatment with Watchman comparable to warfarin in patients with non-valvular atrial fibrillation.
"Although noninferiority was not achieved for overall efficacy, event rates were low … [and] procedural safety has significantly improved," the study showed. "This trial provides additional data that LAA occlusion is a reasonable alternative to warfarin therapy for stroke prevention in patients with NVAF who do not have an absolute contraindication to short-term warfarin therapy."
Boston Scientific spokeswoman Nisha Deo told MassDevice.com via email that the company is looking forward to "presenting the totality of evidence for the Watchman" at the upcoming FDA advisory panel hearing.
"BSC strongly believes that the Watchman clinical datasets support the safety, efficacy and positive benefit-risk ratio for the therapy in appropriately selected patients, consistent with our proposed labeling," Deo wrote. "We will not provide further commentary as it is our policy not to comment on PMA submissions or ongoing discussions with the FDA."
Prevail investigator Dr. Robert Sommer of Columbia University Medical Center in New York told MedPage today that Prevail, which Sommer said was designed to prove safety rather than efficacy, might have shown different results than the earlier Protect AF trial because of the unexpectedly good performance of warfarin.
"Why did Protect-AF show a clear benefit of [LAA] closure versus warfarin and Prevail did not?"he said. "Prevail is interesting only because the Coumadin patients did so much better than anticipated, and that is probably the big reason why there is a difference between the 2 studies."
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