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BACKGROUND: Whether successful catheter ablation for atrial fibrillation eliminates the need for long-term oral anticoagulant therapy is unknown.

METHODS: We conducted an international, open-label, randomized, blinded-outcome-assessment trial involving 1284 patients who had undergone successful catheter ablation for atrial fibrillation at least 1 year earlier and had a CHA2DS2-VASc score (scores range from 0 to 9, with higher scores indicating a higher risk of stroke) of 1 or more (or =2 for women or for patients in whom vascular disease was a risk factor). Patients were randomly assigned to receive either aspirin (at a dose of 70 to 120 mg daily, depending on availability in the local jurisdiction) or rivaroxaban (at a dose of 15 mg) and followed for 3 years. Magnetic resonance imaging (MRI) of the head was performed after enrollment and at 3 years. The primary outcome was a composite of stroke, systemic embolism, or new covert embolic stroke (defined by =1 new infarct measuring =15 mm on MRI) at 3 years.

RESULTS: A total of 641 patients were assigned to the rivaroxaban group and 643 to the aspirin group. A primary-outcome event occurred in 5 patients (0.31 events per 100 patient-years) in the rivaroxaban group and in 9 patients (0.66 events per 100 patient-years) in the aspirin group (relative risk, 0.56; 95% confidence interval [CI], 0.19 to 1.65; absolute risk difference at 3 years, -0.6 percentage points; 95% CI, -1.8 to 0.5; P = 0.28). New cerebral infarcts measuring less than 15 mm occurred in 22 of 568 patients (3.9%) in the rivaroxaban group and in 26 of 590 patients (4.4%) in the aspirin group (relative risk, 0.89; 95% CI, 0.51 to 1.55). Fatal or major bleeding (the composite primary safety outcome) had occurred in 10 patients (1.6%) with rivaroxaban and in 4 patients (0.6%) with aspirin (hazard ratio, 2.51; 95% CI, 0.79 to 7.95) at 3 years.

CONCLUSIONS: Among patients who had had successful catheter ablation for atrial fibrillation at least 1 year earlier and had risk factors for stroke, treatment with rivaroxaban did not result in a significantly lower incidence of a composite of stroke, systemic embolism, or new covert embolic stroke than treatment with aspirin. (Funded by Bayer and others; OCEAN ClinicalTrials.gov number, NCT02168829.).

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