A prospective cohort of patients with mitral stenosis and no history of atrial arrhythmias showed no decrease in the incidence of atrial fibrillation (AF) after successful versus unsuccessful Inoue balloon percutaneous balloon mitral valve commissurotomy. Advanced age and left atrial dimension best predicted which patients developed AF during follow-up, whereas percutaneous balloon mitral valve commissurotomy procedural success and left atrial pressure reduction did not have an impact on incidence of AF.