Troponin T is a better predictor than creatine kinase-MB of long-term mortality after coronary artery bypass graft surgery

Abstract

Elevations of creatine kinase-MB (CK-MB) and cardiac troponin T (cTnT) have an uncertain long-term prognostic value after coronary artery bypass graft (CABG) surgery. We aimed to test the hypothesis that CK-MB and cTnT are predictors of long-term survival after CABG and to assess which of these 2 biomarkers is the better predictor. A total of 1,350 consecutive patients undergoing isolated on-pump CABG had CK-MB and cTnT measured at 7, 20, and 44 hours, postoperatively. The end point was all-cause mortality, and during the median follow-up time of 6.1 years, 207 patients (15.3%) died. Both peak CK-MB and peak cTnT independently predicted long-term mortality (hazard ratio [HR] 1.003, 95% confidence interval [CI] 1.001-1.005, P = .007, and HR 1.31, 95% CI 1.17-1.46, P <.001, respectively) when analyzed in separate multivariate Cox models, adjusting for baseline demographic characteristics and perioperative risk factors. However, when analyzed simultaneously in the same Cox model, cTnT was a significant predictor (HR 1.31, 95% CI 1.13-1.51, P <.001), whereas CK-MB was not (P = .99). Similar results were found when the biomarkers were analyzed together in a Cox model adjusting for European System for Cardiac Operative Risk Evaluation. The differences in mortality between the biomarker groups were consistent also when analyzing strict quartiles of peak values of CK-MB and cTnT (P = .81 and P = .001, respectively). Both CK-MB and cTnT are predictors of mortality after CABG surgery; however, our data suggest that cTnT is a better predictor of long-term mortality after CABG surgery than CK-MB.