Anıl AKBAŞ, Tamer CEBE, Ahmet İbrahim BALKAYA
Cardiovascular Surgery and Interventions - 2026;13(2):66-71
Objectives: This study aimed to compare the discrimination and calibration performances of the Society of Thoracic Surgeons (STS) PROM and European System for Cardiac Operative Risk Evaluation II (EuroSCORE II) risk models in predicting early postoperative mortality and to evaluate the prognostic value of preoperative clinical factors in patients undergoing isolated coronary artery bypass grafting (CABG). Methods: Sixty-four consecutive patients (mean age: 62.1+/-10.1 years; 71.9% male) who underwent isolated CABG were included in this retrospective, single-center study. The discriminative capacity of the models was evaluated using receiver operating characteristic (ROC) curve analysis and the DeLong test, while calibration was assessed using observed/expected (O/E) mortality ratios. Results: The overall operative mortality was 21.9% (n=14), demonstrating a statistically significant increase with surgical urgency (2.8% in the elective group; p<0.001). Both models underestimated actual mortality, particularly in emergency and salvage cases (O/E ratios: EuroSCORE II 24.7, STS PROM 21.9). In comparative group analyses, preoperative leukocyte (white blood cell) levels were significantly higher in the mortality group (11.95+/-3.46 vs. 9.15+/-2.74, p=0.006). ROC analysis revealed similar discriminatory power for both models (area under the curve: STS PROM 0.749, EuroSCORE II 0.740; p=0.866). However, the sensitivity of the STS PROM model (71.4%) was higher than that of EuroSCORE II (57.1%). Conclusion: In our small, single-center exploratory cohort undergoing isolated CABG, surgical urgency and elevated leukocyte levels were observed as potential clinical parameters associated with early mortality in comparative group analyses. Although the STS PROM and EuroSCORE II models demonstrated acceptable discriminatory capacity, they tend to underestimate operative mortality in cases of high surgical urgency. Nevertheless, for regional centers managing high-risk profiles, the STS PROM model may represent a more practical option when prioritizing sensitivity. These findings are strictly hypothesis-generating and warrant validation in larger, multicenter cohorts.
