"This is a significant development because for the first time we were able to demonstrate that the WATCHMAN device was superior to warfarin for both primary efficacy and also mortality," said Dr. Reddy. "This has tremendous upside potential for patients. In the PROTECT AF trial, LAA closure with the WATCHMAN device demonstrated the potential for a device-based approach to reduce the risk of stroke in AF patients. As clinicians, we often feel uncomfortable with life-long systemic anticoagulation therapy in patients because of an increased risk of falls and bleeding. The four-year data provide additional support for LAA closure as a potential viable long-term alternative to chronic warfarin therapy for patients to reduce the risk of stroke."The PROTECT AF clinical trial is a multicenter, prospective randomized clinical trial designed to demonstrate the safety and effectiveness of the Boston Scientific WATCHMAN device in patients with non-valvular AF who are eligible for warfarin therapy and meet certain stroke risk factors. A total of 707 patients from 59 centers were randomized 2:1 to device or warfarin control. Results The PROTECT AF trial achieved superiority for the combined endpoint of all stroke, cardiovascular or unexplained death and systemic embolism. 
- The observed primary efficacy event rate was 2.3 percent and 3.8 percent in the WATCHMAN and control groups, respectively, demonstrating a 40 percent relative risk reduction in primary efficacy in the WATCHMAN group (RR = 0.60, posterior probability of superiority = 96 percent).
- All-Cause Mortality: the WATCHMAN group was superior to the control group, 3.2 percent to 4.8 percent respectively, representing a 34 percent relative risk reduction in all-cause mortality in the WATCHMAN group (HR = 0.66, p=0.0379).
- Cardiovascular Mortality: the WATCHMAN group was superior to the control group, 1.0 percent and 2.4 percent respectively, representing a 60 percent relative risk reduction in cardiovascular death in the WATCHMAN group (HR = 0.40, p=0.0045).