Patients with atrial fibrillation who are ineligible for oral anticoagulation had 75 percent fewer ischemic strokes and system embolisms if they received the Watchman left atrial appendage occlusion device than if they received aspirin alone.
Lead researcher Vivek Y. Reddy, MD, MS, of the Icahn School of Medicine at Mount Sinai in New York, and colleagues published their results online in The Journal of the American College of Cardiology on May 2.
In March 2015, the FDA approved the Watchman device (Boston Scientific) as an alternative to warfarin for high-risk patients with nonvalvular atrial fibrillation.
Previously, the PROTECT AF and PREVAIL trials showed that the Watchman device was effective for stroke prevention. However, the researchers noted that patients in those trials received six weeks of oral anticoagulation.
This analysis examined the ASAP (ASA Plavix Feasibility Study With Watchman Left Atrial Appendage Closure Technology), which enrolled 150 warfarin-ineligible patients with nonvalvular atrial fibrillation at four centers. All patients received the Watchman device.
Patients received aspirin and clopidogrel for six months after implantation. They then received aspirin.
After a median follow-up period of 55.4 months, the annualized ischemic stroke or systemic embolism rate was 1.8 percent, which was 75 percent lower than the expected annual rate of 7.3 percent if they received aspirin alone. The rate was similar to the 1.6 percent rate found in the PROTECT-AF and PREVAIL studies.
In the ASAP study, the annual hemorrhagic stroke rate was 0.54 percent, the annual all-stroke rate was 2.4 percent, the annual cardiovascular/unexplained death rate was 2.3 percent, the annual all-cause mortality rate was 4.6 percent, the annual transient ischemic attack rate was 0.9 percent and the annual major bleeding event rate was 1.8 percent.
The researchers noted a few limitations of the ASAP study, including that it was non-randomized. Thus, the results could be considered hypothesis-generating but nothing more. Also, the study’s plan did not include follow-up beyond two years, and it did not have independent neurologic adjudication of events.