['Atrial fibrillation (AF) is the most common arrhythmia after coronary artery bypass grafting (CABG). It is a considerable source of morbidity, prolongs hospital stay and increases costs of treatment. Atrial cannulation, cardiopulmonary bypass and cardioplegic arrest have been suggested to play a role in the development of AF after CABG. The aim of this case-control study was to evaluate the role of cardiopulmonary bypass and cardioplegic arrest in the development of postoperative AF.', 'Data from 114 patients undergoing CABG without cardiopulmonary bypass and cardioplegic arrest (off-pump) between October, 1998 and December, 2002 were evaluated for the occurrence of postoperative AF. Each patient was individually matched by gender, age (+/-3 years), left ventricle ejection fraction (+/-5%), history of myocardial infarction, unstable angina, and beta-blocker medication with patients undergoing CABG with cardiopulmonary bypass and cardioplegic arrest (on-pump) during the same period. The data from off-pump and on-pump groups were compared.', 'Off-pump and on-pump groups had similar preoperative characteristics. The number of distal anastomoses was lower in the off-pump (2.3+/-0.9) than in the on-pump (3.9+/-1.1, (P<0.001) group. However, the incidence of postoperative AF in the off-pump (36.8%) and the on-pump groups (36.0%) did not differ from each other. Old age was the only independent predictor of AF after CABG.'] Does cardioplegic arrest increase the risk of atrial fibrillation after coronary artery bypass surgery?