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 48h 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 30days 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).