Officials at Boston Scientific (NYSE:BSX) announced this week that they would reveal only limited patient safety results when they present data from a clinical trial of the Watchman stroke prevention implant at the American College of Cardiology conference this week.
The Massachusetts-based medical device giant revealed in a press release that it plans to "present the acute procedural safety results of the PREVAIL clinical trial," keeping 2 other safety endpoints under wraps for the time being.
"We find this highly unusual given that Prevail is one of the featured late-breaking trials at ACC," Wells Fargo analyst Larry Biegelsen said in a note to investors. The hesitation to reveal the full safety results may indicate that the Watchman device failed to meet the other endpoints, he speculated. "Given the unusual nature of this development, i.e. only one of 3 primary endpoints being presented, we would not be surprised to see this decision change by Saturday."
Representatives for the ACC conference, which begins this weekend, said they were "surprised" by Boston Scientific’s announcement and that they would investigate further.
The company is still analyzing the Watchman trial’s efficacy data to determine whether it will be ready for presentation, spokesman Steve Campanini told Bloomberg news.
The Watchman device, which is already available in 30 countries, is introduced via catheter and threaded into the heart to close off the left atrial appendage and capture any blood clots that may form there. The device aims to reduce the risk of stroke and may potentially eliminate the need for long-term use of blood-thinning medications.
Natick, Mass.-based Boston Scientific acquired the Watchman device along with AtriTech for up to $375 million in 2011. Last summer the company closed enrollment in a 2nd trial of the device, with more than 2,000 subjects signing on for the randomized comparison of Watchman with warfarin in high-risk patients with atrial fibrillation. In August the device won expanded CE Mark approval in the European Union for the catheter-based clot-capture system, to patients with atrial fibrillation who can’t be treated with warfarin or new oral anticoagulants.