Background: Postoperative atrial fibrillation is the most common arrhythmia after coronary artery bypass grafting, with a reported incidence of 10% to 60%. Preoperative clinical and Echocardiographic data, especially the atrial electromechanical interval, predict postoperative atrial fibrillation in elective coronary artery bypass patients. Methods: A prospective study evaluated preoperative clinical and Echocardiographic data in 192 patients who underwent elective coronary artery bypass from 2010 to 2012. Results: 18 (9.37%) patients developed postoperative atrial fibrillation. Compared to patients without postoperative atrial fibrillation, these 18 had significantly longer intensive care unit and hospital stays, they were significantly older (58.62 ±10.02 vs. 53.22±8.23 years; P=0.02), with a larger left atrial volume (83.39±8.31 vs. 55.47±8.37 cm3,P=0.001), longer atrial electromechanical interval (133.67±8.15 vs. 98.05±6.71 ms P