Each surgical risk prediction model requires a validation analysis within a large ‘real-life’ sample. The aim of this study is to validate the age, creatinine and ejection fraction (ACEF) II risk score compared with the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II.

All patients operated on at 8 Italian cardiac surgery centres in the period 2009–2019 with available data for the calculation of EuroSCORE II and ACEF II were included in the study. Mortality was recorded and receiver operating characteristic curves were plotted for the overall study population and for different patient subgroups according to the type of surgery.

A total of 14 804 patients were enrolled [median age of 70 (62–77) years, 35.4% female], and among these, 3.1% underwent emergency surgery. Thirty-day mortality was 2.84% (n = 420). In the total population, the area under the curve with EurosCORE II was significantly higher than that recorded with ACEF II [0.792, 95% confidence interval (CI) 0.79–0.8 vs 0.73, 95% CI 0.73–0.74; P < 0.001]. This finding was also confirmed in the patient subgroups undergoing isolated valve surgery (EuroSCORE II versus ACEF II: 0.80, 95% CI 0.79–0.814 vs 0.74, 95% CI 0.724–0.754; P = 0.045) or isolated aortic surgery (0.754, 95% CI 0.70–0.79 vs 0.53, 95% CI 0.48–0.58; P = 0.002). In contrast, the 2 scores did not differ significantly in patients undergoing isolated bypass surgery (0.8, 95% CI 0.78–0.81 vs 0.77, 95% CI 0.75–0.78; P = 1).

In both the overall population and patient subgroups, EuroSCORE II proved to be more accurate than ACEF II. However, in patients undergoing bypass surgery, ACEF II proved to be an easy and simple to use risk score, demonstrating comparable risk prediction performance with the more complex EuroSCORE II.