European Registry Results Presented for Boston Scientific's Watchman LAAC Device
May 12, 2017—Boston Scientific Corporation announced positive safety and efficacy rates of the Watchman left atrial appendage closure device from the EWOLUTION registry, which were presented during a late-breaking clinical trial session at Heart Rhythm 2017, the Heart Rhythm Society's 38th annual scientific session in Chicago, Illinois. Additional data from EWOLUTION will be presented on May 18 at the annual EuroPCR scientific congress in Paris, France.
The company reported that data confirmed that the Watchman device had a high implantation success rate and was effective in reducing stroke for patients with nonvalvular atrial fibrillation (AF), including patients deemed unsuitable for oral anticoagulation.
According to Boston Scientific, the prospective, single-arm, multicenter EWOLUTION registry evaluated 1,025 patients with nonvalvular AF who are at a high risk for stroke and systemic embolism. Patients were enrolled at 47 centers throughout Europe, Russia, and the Middle East. More than 70% of the patients were deemed unsuitable for short- or long-term anticoagulation at the time of Watchman implantation. Transient ischemic attacks, ischemic stroke, vascular disease, and a history of major bleeding were present in approximately half of the patients.
At 1 year after device implantation, there was an 84% reduction in the annual stroke rate (1.1 vs 7.2 per 100 patient-years) as compared to predicted rates of untreated patients with a similar risk profile, as well as a 48% reduction in the annual rate of major bleeding (2.6 vs 5 per 100 patient-years) as compared to predicted rates for patients treated with warfarin.
The company noted that CHA2DS2VASc and HAS-BLED scores have been validated to predict annual rates of ischemic stroke and bleeding, respectively. To provide context for the results given the absence of a control group, analyses compared EWOLUTION event rates to rates for patients of a similar risk profile.
In the company's press release, EWOLUTION Principal Investigator Lucas V.A. Boersma, MD, commented, "This impressively low ischemic stroke rate favors left atrial appendage closure as an important therapy for patients ineligible for long-term oral anticoagulation. The results further validate the utility of the Watchman device as an excellent alternative to anticoagulant therapy and its related bleeding risks for patients with nonvalvular AF." Dr. Boersma is an electrophysiologist at St. Antonius Hospital in Utrecht, the Netherlands.