Prospective randomized evaluation of the watchman left atrial appendage closure device in patients with atrial fibrillation versus long-term warfarin therapy: The PREVAIL trial

Abstract

Objectives: Assessing the safety and effectiveness of left atrial appendage (LAA) (pouch found in the upper chambers of the heart) occlusion, using the Watchman device compared to long term warfarin therapy (drug that reduces clot formation), in preventing the risk of stroke in patients with atrial fibrillation (most common type of irregular heart beat). 90% of strokes in atrial fibrillation arise from clots forming in this pouch. By mechanically blocking it using the device less clots are suggested to be formed. This is an alternative to taking warfarin especially in patients who cannot take it.

Setting and participants: 50 sites in the United States enrolled 407 participants. After being randomly allocated, the device group had 269 participants and warfarin group (comparator)had 138 participants.

Method: Patients with atrial fibrillation and at high risk of stroke were randomly allocated a group after they were deemed eligible. Patients in the device group had to take warfarin and aspirin for 45days till the complete closure of the LAA. The oral anticoagulant was followed by dual antiplatelet therapy until 6months and then ASA. Patients in the warfarin group have to take it for life and were continually monitored. The study ran for 26months.

Main outcome measures: The trial assessed the rate of adverse events using three endpoints:

Results: The PREVAIL trial was not designed to show superiority, but non-inferiority. It met the safety endpoint and one efficacy endpoint for the watchman device compared to long term warfarin for overall efficacy of the device. The results established that LAA occlusion is not worse than warfarin intake for the prevention of stroke more than 1week after randomization. Compared to previous trials, the safety of the device has also improved.

Conclusion: LAA occlusion is a reasonable alternative to chronic warfarin therapy in stroke prevention for patients with atrial fibrillation.