To study the effect of atorvastatin on recurrence of atrial fibrillation (AF) after electrical cardioversion (EC), 48 patients with AF lasting 48 hours who were scheduled for EC were randomized to the atorvastatin (group I) and control (group II) groups. Six patients in group I (25%) and 2 patients in group II (8.3%) had spontaneous conversion before EC (p >0.05). The end point was the recurrence of AF during 3 months of follow-up. Eighteen patients in group I (12.5%) and 11 patients in group II (45.8%) had recurrence (p = 0.01, log-rank test). With the Cox proportional model, the predictors of recurrence included a body mass index of 25 to 30 kg/m2 (relative risk [RR] 0.07, 95% confidence interval [CI] 0.008 to 0.59), body mass index > or = 30 kg/m2 (RR 0.24, 95% CI 0.08 to 0.72), AF duration of > or = 3 months (RR 0.28, 95% CI 0.09 to 0.83), diabetes mellitus (RR 0.34, 95% CI 0.12 to 0.98), and left atrial diameter of > or = 45 mm (RR 0.23, 95% CI 0.07 to 0.74). Atorvastatin was associated with a significantly reduced risk of developing AF (unadjusted RR 0.23, 95% CI 0.064 to 0.82, p = 0.024). This association remained significant after adjustment for these predictors (adjusted RR 0.19, 95% CI 0.052 to 0.72, p = 0.01). High-sensitivity C-reactive protein levels at baseline were not different between the 2 groups (p = 0.92). Although the high-sensitivity C-reactive protein levels decreased significantly 48 hours after EC compared with the baseline levels in group I (2.82 +/- 1.46 vs 2.56 +/- 1.3 mg/dl, p = 0.02), no significant change occurred in group II (2.87 +/- 0.8 vs 2.84 +/- 0.8 mg/dl, p = 0.09). In conclusion, atorvastatin decreased the recurrence rate of AF after EC.