Background: Data on predictors of failure of electrical cardioversion of acute atrial fibrillation are

scarce.

Methods: We explored 6,906 electrical cardioversions of acute (<48 hours) atrial fibrillation in 2,868 patients in a retrospective multicenter study.

Results: The success rate of electrical cardioversion was 94.2%. In 26% of unsuccessful cardioversions, the cardioversion was performed successfully later. Antiarrhythmic drug therapy, short (<12 hours) duration of atrial fibrillation episode, advanced age, permanent pacemaker, history of atrial fibrillation episodes within 30 days before cardioversion, and β-blockers were independent predictors of unsuccessful electrical cardioversion. In the subgroup of patients with cardioversion of the first atrial fibrillation episode (N = 1,411), the short duration of episode (odds ratio [OR] = 2.28; 95% confidence interval [CI] 1.34–3.90, P = 0.003) and advanced age (OR = 1.03; 95% CI 1.02–1.05, P < 0.001) were the only independent predictors of unsuccessful cardioversion. After successful cardioversion, the rate of early (<30 days) clinical recurrence of atrial fibrillation was 17.3%. The index cardioversion being performed due to the first atrial fibrillation episode was the only predictor of remaining in the sinus rhythm.

Conclusion: A short (<12 hours) duration of acute atrial fibrillation is a significant predictor of

unsuccessful cardioversion, especially during the first attack. First atrial fibrillation episode was the only predictor of remaining in the sinus rhythm.