Objective To examine the incidence and risk factors associated with atrial fibrillation in elderly coronary heart disease patients who underwent off-pump coronary artery bypass surgery.Methods From Jun.2008 to Jun.2009,one hundred and eleven patients received OPCAB in our hospital.Clinical data including coronary angiography,diseased vessels,number of bypass grafts,postoperative electrolyte,postoperative hemodynamic measurements,anti-arrhythmic drugs used and other risk factors for atrial fibrillation was collected and reviewed individually.The mean age of patients was(73.19±2.79)years(range from 70 to 82 years).Seventy-nine patients were male and 32 were female.The mean left ventricular ejection fraction(LVEF)was 0.57±0.12,NYHA Ⅰ-Ⅳ.All patients received OPCAB.Saphenous vein(SV)and left internal mammary artery(LIMA)were harvested and used as grafts.LIMA was routinely anastomosed to the left anterior descending artery (LAD),and SV was anastomosed to the other target vessels.The average number of grafts.was(2.79±0.54)per case.The mean operation time was(3.70±0.88)hours and the duration of ICU-staying was(1.32±0.94)days.The patients were divided into 2 groups:atrial fibrillation group and non-atrial fibrillation group.Results Four deaths occurred perioperatively.The mortality was 3.42%.Major postoperative complications included low cardiac output,respiratory dysfunction and acute kidney injury.Twenty seven out of 111 patients who underwent off-pump coronary artery bypass surgery had atrial fibrillation postoperatively.The incidence was 24.3%.Single factor analysis revealed that CVP,serum levels of potassium,magnesium,and SPO2 were lower significantly in atrial fibrillation group than those in the non-atrial fibrillation group,P<0.05.Conclusion Changes of perioperative electrolytes and circulating blood volume,decline in the oxygen saturation,and the occurrence of perioperative myocardial infarction after coronary artery bypass surgery were the risk factors associated with atrial fibrillation.