The New England Journal of MedicineApixaban for Stroke Prevention in Subclinical Atrial Fibrillation

Apixaban vs. Aspirin in Subclinical Atrial Fibrillation: Balancing Stroke Reduction and Bleeding Risk

This clinical trial evaluates the efficacy and safety of apixaban compared to aspirin in patients with subclinical atrial fibrillation, a condition linked to increased stroke risk but often asymptomatic and detectable only through continuous monitoring. The study aims to discern optimal treatment strategies in this patient group.

Study Design:

• Patient Group: 4,012 patients, mean age 76.8 years, 36.1% women.
• Condition: Subclinical atrial fibrillation lasting 6 minutes to 24 hours.
• Treatment: Randomized to receive either apixaban (5 mg twice daily or 2.5 mg when indicated) or aspirin (81 mg daily).
• Monitoring: Shift to anticoagulation if atrial fibrillation exceeds 24 hours or becomes clinical.
• Primary Outcomes: Stroke or systemic embolism (efficacy); major bleeding (safety).

Key Findings:

• Incidence of Stroke/Systemic Embolism: Lower in apixaban group (0.78% per patient-year) than aspirin group (1.24%).
• Major Bleeding: Higher in apixaban group (1.71% per patient-year) compared to aspirin (0.94%).
• Overall Assessment: Apixaban reduced stroke risk but increased major bleeding compared to aspirin.

Patients with atrial fibrillation are at a 5 times higher risk of stroke and 3 times more likely to experience heart failure compared to those without the condition.

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