Predictive Performances of ACEF, ACEF II, Updated ACEF II, and EuroSCORE II Risk Scores in Patients Undergoing Isolated Off-pump Coronary Artery Bypass Grafting

This study evaluated the performances of the age, creatinine, and ejection fraction (ACEF) I and II scores and compare them with that of the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II score in patients who underwent isolated off-pump coronary artery bypass grafting (OPCABG). Additionally, this study was designed to externally validate the performance of the updated ACEF II score. Retrospective observational study. A total of 936 patients who underwent OPCABG between January 1, 2013, and December 31, 2022, at a tertiary teaching center were included. None. Predicted operative mortality was calculated using a risk score model. The predictive performance of each score was evaluated using receiver operating characteristic curves and calibration plots. The ACEF II score demonstrated the highest C-statistic (area under the curve = 0.831, 95% confidence interval: 0.691-0.971), while the C-statistics for ACEF I, updated ACEF II, and EuroSCORE II were 0.793 (0.645-0.940), 0.698 (0.524-0.872), and 0.780 (0.606-0.954), respectively. The ACEF II score exhibited significantly better discriminative performance than the updated ACEF II score (p = 0.010); however, no significant differences were observed compared with the ACEF I and EuroSCORE II scores (p = 0.118 and 0.354, respectively). ACEF I and II scores are reliable risk stratification models with performances comparable to the EuroSCORE II score in patients undergoing isolated OPCABG. However, the updated ACEF II score failed to demonstrate improved performance.