- Question
- Is apixaban superior to aspirin for preventing stroke and systemic embolism in patients with device-detected subclinical atrial fibrillation?
- Design
- Randomized, double-blind, double-dummy trial of 4012 patients assigned to apixaban or aspirin, with a mean follow-up of 3.5 years.
- Population
- Patients with subclinical atrial fibrillation lasting 6 minutes to 24 hours, detected by continuous monitoring with pacemakers or defibrillators; mean age 76.8 years and mean CHA2DS2-VASc score 3.9.
- Intervention
- Apixaban 5 mg twice daily (2.5 mg twice daily when indicated).
- Control
- Aspirin 81 mg once daily.
- Primary outcome
- Composite of stroke or systemic embolism, assessed in the intention-to-treat population; the primary safety outcome was major bleeding, assessed in the on-treatment population.
- Results
- Stroke or systemic embolism occurred in 55 patients on apixaban (0.78% per patient-year) and in 86 on aspirin (1.24% per patient-year) (HR 0.63; 95% CI 0.45 to 0.88; P = 0.007).
- Safety
- Major bleeding was more frequent with apixaban (1.71% per patient-year) than with aspirin (0.94% per patient-year) (HR 1.80; 95% CI 1.26 to 2.57; P = 0.001). Fatal bleeding occurred in 5 patients on apixaban and 8 on aspirin.
- Conclusion
- In subclinical atrial fibrillation, apixaban lowered the risk of stroke or systemic embolism compared with aspirin, at the cost of a higher risk of major bleeding.
- Why it matters
- The trial provided randomized evidence on anticoagulation in subclinical atrial fibrillation, a setting that was previously uncertain, and shows that the decision must balance the reduction in embolic events against the increased bleeding risk.
Card generated automatically with AI from the abstract of the original publication and the trial registry; every figure was checked against those sources. It may contain errors: verify the data at the source before using it for clinical decisions.
Generated on October 7, 2026