BackgroundPostoperative atrial fibrillation (POAF) occurs in 20-40% patients who received isolated coronary artery cardiac bypass surgery (CABG). Several POAF risk prediction models have been developed, but none of them is widely adopted in practice. Our objective was to derive and validate a simple scoring system to estimate POAF risk after isolated CABG, using easily available clinical information. MethodsMedical records of 1,000 consecutive patients undergoing isolated CABG were reviewed. The data of first 700 patients were used for model derivation and data of the remaining 300 patients were used for model validation. Discrimination and calibration of the newly developed model were assessed. ResultsPOAF incidence in both the derivation and validation cohorts was 27.3%. Age 65, history of hypertension, heart failure, and myocardial infarction were independently associated with POAF risk. Risk scores were calculated by summing weighting points for each independent predictor. The score 3 was associated with high POAF incidence (41.1% in the derivation cohort and 44.3% in the validation cohort). The positive and negative POAF predictive value was 41.1% and 78.5%, respectively, in the derivation cohort, and 44.3% and 80.8%, respectively, in the validation cohort, when the cut-point score 3 was used. The Hosmer-Lemeshow goodness-of-fit test P-values were 0.917 and 0.894 in the derivation cohort and validation cohort, respectively. ConclusionsThis POAF risk following isolated CABG can be predicted with simple patient characteristic during the preoperative period. Patients with high risk scores (3) may constitute a target population for POAF prevention and prolonged postoperative surveillance.