Our objectives were to study the success rate of electrical cardioversion after percutaneous balloon mitral valvuloplasty (PBMV) in patients with symptomatic moderate-to-severe mitral stenosis and atrial fibrillation (AF) and the maintenance rate of sinus rhythm for < or =1 year. We studied patients with mitral stenosis and AF who were scheduled for PBMV. Electrical cardioversion was performed 1 month after PBMV. Amiodarone 200 mg/day was started the day after PBMV. The primary outcomes studied were the rate of successful cardioversion and the maintenance rate of sinus rhythm at 12 months. Of 272 patients scheduled for PBMV, 70 were enrolled. The average age was 45 +/- 10 years. The average mitral valve area was 0.82 +/- 0.22 cm(2). Cardioversion was successful in 50 patients (71%). Logistic regression analysis revealed that left atrial size and associated aortic valvular disease were predictors of successful cardioversion. Of the 50 patients with successful cardioversion, AF recurred in 24 (48%). An increased left atrial diameter was the only factor associated with AF recurrence at 12 months. In conclusion, good candidates for cardioversion after PBMV were those with a left atrial diameter of <60 mm and no associated aortic valvular disease -- approximately 43% of patients with AF scheduled for PBMV. In this group, about 2/3 were in sinus rhythm at 12 months after cardioversion.