Boston Scientific has completed enrolment in the PREVAIL confirmatory study, designed to gain US Food and Drug Administration (FDA) approval for the Watchman Left Atrial Appendage (LAA) Closure device.
The prospective, randomised 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.
“Watchman is the most clinically studied device of its kind,” said Vivek Reddy, director of Cardiac Arrhythmia Service at Mount Sinai Medical Center and principal investigator of the PREVAIL study. “Watchman has the potential to provide atrial fibrillation patients with a safe and effective first-in-class device-based solution to reduce risk of stroke.”
The PREVAIL study began enrolment 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 programme for Watchman includes two landmark studies: the PROTECT AF trial and the ASA Plavix (ASAP) study. In the multicentre, randomised PROTECT AF trial, the Watchman device proved to be non-inferior to warfarin and demonstrated a 38% relative risk reduction for stroke, cardiovascular death and systemic embolism compared to long-term warfarin therapy in 707 patients. Data from the prospective, multicentre ASAP study showed a 77% reduction of ischaemic stroke risk in patients with AF implanted with the Watchman device and not eligible for blood-thinning medications.
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 USA, 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.