Using CK-MB and hs-cTnT to Predict 30-Day Mortality After CABG: A Combined Biomarker Risk-Stratification Approach

Background Accurate diagnosis of perioperative myocardial infarction after coronary artery bypass grafting remains challenging due to uncertainty over postoperative cardiac biomarker interpretation. Objectives The authors aimed to evaluate the prognostic value and performance of postoperative creatine kinase-myocardial band (CK-MB) and high-sensitivity cardiac troponin T (hs-cTnT) and explore a combined approach to identify patients at risk of early death. Methods This multicenter cohort study involved 9,856 patients undergoing isolated coronary artery bypass grafting at hospitals in Innsbruck, Freiburg, Gothenburg, and Reykjavik. A combined biomarker matrix was created to assess synergistic effects. Associations of biomarkers with 30-day all-cause mortality were evaluated using multivariable Cox regression (adjusted HR) and area under the receiver-operating curve (AUC) analysis. Results Thirty-day all-cause mortality was 2.0%. Median peak values within 72 hours postsurgery were 2.24 (Q1-Q3: 1.66-3.36) × upper reference limit for CK-MB and 52.06 (Q1-Q3: 29.79-90.00) × upper reference limit for hs-cTnT. Both postoperative CK-MB (adjusted HR: 1.95; 95% CI: 1.79-2.12; P < 0.001) and hs-cTnT (adjusted HR: 1.71; 95% CI: 1.61-1.82; P < 0.001) were associated with higher mortality risk per doubling in concentration independent of EuroSCORE II. Predictive accuracy of CK-MB and hs-cTnT was similar (AUC: 0.787 vs 0.784; P = 0.99), yet stratification using Youden-derived thresholds identified distinct patient subgroups with limited overlap. In a combined analysis, mortality risk was increased only when CK-MB was in the top tertile and hs-cTnT in the mid (adjusted HR: 4.34; 95% CI: 1.78-10.62; P < 0.001) or top tertile (adjusted HR: 14.78; 95% CI: 6.85-31.88; P < 0.001). Conclusions The combined use of CK-MB and hs-cTnT enables a simple and robust risk-stratification strategy for early postoperative mortality, with direct implications for clinical surveillance and future cardiac surgery trials.