Boston Scientific, sponsor of the PREVAIL study set to be featured March 9 as a late-breaking clinical trials at the American College of Cardiology (ACC) scientific sessions in San Francisco, announced that the presentation will focus on acute procedural safety results and not the complete results.

PREVAIL is a randomized controlled study that compares the Watchman Left Atrial Appendage Closure Device to long-term warfarin therapy in patients with atrial fibrillation who are at risk for stroke. David R. Holmes Jr., MD, of the Mayo Clinic in Rochester, Minn., was scheduled to present final results that included safety and efficacy endpoints.

On March 4, Boston Scientific listed only the acute procedural safety results being presented in a press release.

The ACC has been in touch with Boston Scientific and the investigators, according to Beth Casteel, director of media relations for the ACC. “We are talking with them about exactly how much data they would be able to present,” she told Cardiovascular Business.

PREVAIL was amended March 1 to launch a prospective, nonrandomized study called “Continued Access to PREVAIL (CAP2).” The goal of the study is to collect additional data of the safety and efficacy of the Watchman device. It is expected to initially enroll 300 patients, with a maximum of 1,500 patients, at 60 investigational sites in the U.S.

In April 2009, an FDA panel voted 7 to 5 to approve the Watchman “with conditions.” The panel noted the positive short-term data of the device during PROTECT AF, which showed that the Watchman reduced the risk of stroke, cardiovascular death and embolism by 30 percent of patients at 27 months of follow-up. The panel questioned the lack of long-term evidence, which PREVAIL was expected to provide.

The Watchman device is not approved for use in the U.S.