Performance of EuroSCORE II compared to EuroSCORE I in predicting operative and mid-term mortality of patients from a single center after combined coronary artery bypass grafting and aortic valve replacement.

Objective: The performance comparison of the recently introduced European System for Cardiac Operative Risk Evaluation II in predicting operative as well as mid-term mortality, with its previous version in patients after combined aortic valve replacement and coronary artery bypass grafting surgery.

Methods: This retrospective analysis included 216 patients operated on at one institution from 01/1999 to 12/2005. Accuracy and calibration of EuroSCORE I and II were assessed by plotting the areas under the receiver operator curves and comparing observed and predicted mortalities.

Results: EuroSCORE II showed, regarding early mortality, a slightly higher discriminatory accuracy with an area under the receiver operator curve of 0.77, while additive and logistic EuroSCORE I areas were 0.749, 0.75, respectively. The highest specificity and sensitivity level was approached for EuroSCORE II at a predicted mortality of 4.4 %. Receiver operator curves concerning mid-term mortality revealed areas for additive, logistic EuroSCORE and EuroSCORE II of 0.745, 0.739 and 0.718 with the highest accuracy levels at predicted mortalities of 6.5, 6.48 and 3.88 %, respectively. Mean predicted mortalities by logistic EuroSCORE and EuroSCORE II were 8.35 and 3.99 %, respectively, while overall observed operative mortality was 6.3 %. In "high-risk" patients (EuroSCORE > 13), EuroSCORE II underestimated early and mid-term outcomes.

Conclusions: Regarding operative mortality, EuroSCORE II showed in this study a slightly higher discriminatory accuracy than EuroSCORE I. There were no significant differences in the calibration of the two model versions in "low-" and "moderate-risk" patients regarding early as well as mid-term mortality. Analyses in larger patient populations will contribute to further model improvement.