Boston Scientific has reported Watchman Left Atrial Appendage Closure (LAAC) device results from a ASA Plavix (ASAP) study.

The multi-center, prospective study, which enrolled 150 patients with contraindications to warfarin, was designed to study the safety and effectiveness of the Watchman device.

Patients with contraindications to warfarin were implanted with the Watchman device and treated with dual antiplatelet therapy for six months post-procedure.

The results demonstrated a reduction in the risk of ischemic stroke by 75% in patients with atrial fibrillation who have a contraindication to oral anticoagulants such as warfarin.

Boston Scientific global chief medical officer Keith Dawkins said, "WATCHMAN is the most studied LAA closure device with more than 2,000 patients enrolled in prospective studies and nearly 4,000 patient-years of follow up."

The company is currently enrolling US patients in the Prevail study which is designed to gain the US Food and Drug Administration approval and the enrollment is expected to be completed in the second quarter of 2012.

The Watchman device has received CE mark approval in 2009, while is limited to investigational use in the US.