SummaryRecent data have shown that statins can help prevent atrial fibrillation (AF). We hypothesized that statins vary in their ability to prevent AF after successful electrical cardioversion (EC).Sixty-five patients (29 receiving atorvastatin and 36 receiving simvastatin) who had undergone successful EC for persistent AF were included in the study. They received statins at least one month before EC, and continued the treatment through 2 years of followup. The statins they received were selected independently by their attending physicians.In the follow-up period, AF reoccurred in 11 (38.0%) patients of the atorvastatin group and in 24 (66.7%) patients of the simvastatin group. Using a logistic regression model, the unadjusted odds ratio (OR) of having an AF recurrence for patients on atorvastatin versus those on simvastatin was 0.31 (95% CI 0.11-0.85, P = 0.02). After adjustment for other potentially confounding variables (age, sex, hypertension, diabetes, ischemic heart disease, echocardiographic characteristics, and therapy), treatment with atorvastatin retained its significance for maintaining sinus rhythm in a multivariate model (OR 0.20, CI 0.04 to 0.98, P < 0.05).Our study suggests that atorvastatin and simvastatin exert different effects on the AF recurrence rate after successful EC. Larger prospective randomized trials are needed to definitively evaluate the role of different statins in patients with AF, especially on AF recurrence after EC. (Int Heart J 2009; 50: 153-160)