Boston Scientific Completes Patient Enrollment in PREVAIL Study for First-in-Class Watchman Device


July 6, 2012

July 6, 2012 — Boston Scientific Corp. has completed enrollment in the PREVAIL confirmatory study, designed to gain U.S. Food and Drug Administration (FDA) approval for the Watchman Left Atrial Appendage (LAA) Closure device. The prospective, randomized trial enrolled 407 patients at 42 sites and is comparing the Watchman device to warfarin in high-risk patients with atrial fibrillation (AF) eligible for long-term warfarin therapy. Patient follow up of six months is required prior to submission to the FDA.

The PREVAIL study began enrollment in November 2010. Patients were randomly selected to receive either the Watchman device or remain on long-term warfarin therapy. Those selected to receive the Watchman device remained on warfarin for 45 days following implant.

Watchman has been studied in more than 2,000 patients, exceeding 4,000 patient-years of follow up. The evidence-based clinical program for Watchman includes two landmark studies: the PROTECT AF trial and the ASA Plavix (ASAP) study. In the multi-center, randomized PROTECT AF trial, the Watchman device proved to be non-inferior to warfarin and demonstrated a 38 percent relative risk reduction for stroke, cardiovascular death and systemic embolism compared to long-term warfarin therapy in 707 patients. Data from the prospective, multi-center ASAP study showed a 77 percent reduction of ischemic stroke risk in patients with AF implanted with the Watchman device and not eligible for blood-thinning medications.

Watchman is a novel device manufactured by Boston Scientific Corporation that is introduced into the heart via a flexible tube (catheter) through a vein in the groin and closes off the LAA. The device is designed to capture any clots that may form in the appendage, reducing the risk of stroke and potentially eliminating the need for long-term use of blood-thinning medications.

Atrial fibrillation affects approximately 15 million patients worldwide and is a disorder that disrupts the ability of the heart to beat regularly and pump blood efficiently. Patients in AF are at a greater risk for stroke due to the migration of clots formed in the LAA. Blood-thinning medications have previously been the only therapy for reducing stroke risk in these patients.

The Watchman device was approved for marketing in Europe and some countries in Asia in 2005. It is contraindicated in patients who are not eligible for anticoagulation therapy.

In the United States, the Watchman device is an investigational device, limited by applicable law to investigational use and not available for sale. The device was developed by Atritech, which Boston Scientific acquired in March 2011.

For more information: