Performance of the ACEF and ACEF II risk scores in predicting mortality after off-pump coronary artery bypass grafting

The age, creatinine, and ejection fraction (ACEF) I and II scores are known to predict operative mortality after cardiac surgery. However, data from few cases of off-pump coronary artery bypass grafting (OPCAB) were considered during the development of these scores. This study aimed to validate and update the ACEF I and II scores for the prediction of in-hospital mortality after OPCAB. Single-center retrospective observational study. Tertiary university hospital. All adult patients (≥18 years) who underwent isolated OPCAB between 2011 and 2020 were included in our analysis. Predicted in-hospital mortality after OPCAB was calculated using ACEF and ACEF II scores. Performance of ACEF I and II scores in predicting in-hospital mortality after OPCAB was evaluated using receiver operating characteristics curves and calibration plots. Scores were recalibrated and modified using the closed testing procedure and multivariable fractional polynomial analysis. In total, 1450 patients were analyzed. The ACEF I and II scores discriminated in-hospital mortality with the c-statistics of 0.86 and 0.83, respectively. The calibration plots revealed that both scores overestimated the risk of in-hospital mortality. The ACEF I score was recalibrated by re-estimating only the model intercept. The ACEF II score was modified by substituting hematocrit with left main coronary artery disease. The c-statistic of the updated ACEF II score increased to 0.86. Both the updated ACEF I and II scores were well-calibrated. The ACEF I and II scores discriminated in-hospital mortality after OPCAB with excellent accuracy, although calibration properties were suboptimal. The updated scores showed even better discrimination and calibration. Thus, the ACEF I and ACEF II scores can be relatively straightforward and useful tools for prognostication of patients undergoing OPCAB. • ACEF I and II scores accurately discriminated in-hospital mortality after OPCAB. • However, calibration performance of the scores was suboptimal. • Updated ACEF I and II scores showed even better discrimination and calibration. • ACEF I and II scores are useful for prognostication of patients undergoing OPCAB.