['Postoperative atrial fibrillation remains a significant source of morbidity after coronary artery bypass grafting. We reviewed the data on 2,569 patients to determine if the absence of cardiopulmonary bypass resulted in a lower incidence of atrial fibrillation.', 'All patients undergoing coronary artery bypass grafting without cardiopulmonary bypass from January 1, 1997 through June 30, 2001 were evaluated for postoperative atrial fibrillation. The data of 252 patients with no cardiopulmonary bypass (group 1) were reviewed and compared with three other patient groups. Group 2 consisted of 1,470 patients using cardiopulmonary bypass during the same study period. Group 3 consisted of 841 patients with a similar number of grafts as the study group but using cardiopulmonary bypass. Group 4 consisted of historical data for 847 patients operated on using cardiopulmonary bypass collected from January 1995 through December 1996. Prophylactic beta-blockade was instituted in January 1997. Groups 1 to 3 received this treatment, but group 4 did not.', 'Group 1 had an incidence of atrial fibrillation of 8.8%. Groups 2, 3, and 4 had incidences of atrial fibrillation of 11.6%, 9.4%, and 28.0%, respectively. When compared with group 1, the incidence of atrial fibrillation in group 4 was statistically different (p <. 0001).'] Does off-pump coronary artery bypass grafting decrease the incidence of atrial fibrillation?