Atrial fibrillation patients with CHA₂DS₂-VASc > 1 benefit from oral anticoagulation prior to cardioversion

Background Electrical cardioversion of atrial fibrillation is associated with an increased risk of embolic stroke, but is generally considered safe if performed within 48 h after onset. Our objective was to investigate if thromboembolism and bleeding in association with cardioversion of atrial fibrillation differed between patients with and without oral anticoagulation. Methods Retrospective study of patients with atrial fibrillation undergoing electrical cardioversion from national Swedish health registries from January 1st 2006 until December 1st 2010. Main outcome measures were thromboembolism and bleeding. Results In total 22,874 atrial fibrillation patients underwent electrical cardioversion, 10,722 with and 12,152 without oral anticoagulation pre-treatment. Patients with low stroke risk (CHA₂DS₂-VASc 0-1) did not suffer from any thromboembolic complications within 30 days after cardioversion. After adjustment for factors included in CHA₂DS₂-VASc and after propensity score matching, patients without oral anticoagulation had higher risk for thromboembolic complications, odds ratio 2.54 (95% confidence interval 1.70-3.79) and odds ratio 2.51 (95% confidence interval 1.69-3.75). There were no significant differences regarding bleeding complications between patients with or without anticoagulation after adjustment for factors included in HAS-BLED, odds ratio 1.08 (95% confidence interval 0.51-2.25), nor after propensity score matching, odds ratio 1.00 (95% confidence interval 0.48-2.10). Conclusion The results suggest that electrical cardioversion without prior anticoagulation may not be safe for patients with risk factors for thromboembolism (CHA₂DS₂-VASc score > 1 point).