Abstract: Objective To investigate the risk factors of postoperative atrial fibrillation (POAF) in patients with onpump coronary artery bypass grafting (ONCAB). Methods The clinical data of 200 patients with ONCAB were retrospectively analyzed. The patients were divided into POAF group (n=52) and non POAF group (n=148) according to the occurrence of POAF after operation. The perioperative data including age and gender of all patients were collected and analyzed. The index of opinion of statistical results was classified by two categories Logistic regression analysis, and the related risk factors of POAF were analyzed. The receiver operating characteristic (ROC) curves of the age, red blood cell (RBC), left atrial diameter (LAD) and left ventricular ejection fraction (LVEF) were analyzed in two groups. Results The incidence rate of POAF was 26%, mostly occurred in the postoperative period from 1 d to 3 d. Compared with non POAF group, the age, the proportion of patients with age ≥ 62.5 years or older, the proportion of patients with LAD ≥ 35 mm, left ventricular end- diastolic diameter and perioperative transfusion of RBC were increased in POAF group, and data of mechanical ventilation time, ICU stay time and hospitalization time were prolonged, but the LVEF level decrease (P < 0.05). Among them, the elderly (≥ 62.5 years), increased LAD (≥ 35 mm), the higher perioperative transmission amount of RBC were the independent risk factors of POAF after ONCAB, and the higher LVEF was a protective factor for ONCAB. The optimal thresholds for age, RBC, LAD and LVEF were 62.5 years, 1U, 35.5 mm, and 0.34. Conclusion The occurrence of POAF after ONCAB is related with age ( ≥ 62.5 years old)， LAD ≥ 35 mm and perioperative transfusion of RBC, which can be used as clinically to predict the occurrence of POAF.

Key words: atrial fibrillation, postoperative complications, risk factors, Logistic models, ROC curve, coronary artery bypass,on-pump