A comparison of cardiac troponin T and creatine kinase-MB for patient evaluation after cardiac surgery

OBJECTIVES The aim of this study was to assess the role of serum markers of myocardial necrosis after cardiac surgery. BACKGROUND The role of serum troponin T (TnT) and creatine kinase-MB (CK-MB) for the risk stratification of patients after cardiac surgery remains undefined. METHODS Serum levels of TnT and CK-MB were measured from 224 patients every 8 h after cardiac surgery. The results of serum cardiac marker testing were correlated with adverse events, including new myocardial infarction (MI), cardiogenic shock or death, Univariable analysis identified factors predictive of complications, while stepwise logistic regression identified independent predictors of postoperative complications. RESULTS Cardiac marker elevation was universal after cardiac surgery. At all time points measured, compared with those patients without complications, the TnT levels from patients with complications were more significantly elevated (all: p < 0.0005). In contrast, among identically timed specimens, the levels of CK-MB from complicated patients were less reliably discriminatory. Multivariable analysis suggested that a TnT level in the highest quintile (greater than or equal to1.58 ng/ml was the strongest predictor of complications, including death (post-op, odds ratio [OR] = 31.0, 9506 confidence interval [CI] 3.67 to 263.1, p = 0.002) or shock I post-op: OR = 18.9, 95% Cl = 2.29 to 156.1, p 0.006 18 h to 24 h: OR = 30.7, 95% CI = 3.75 to 250.7, p = 0.0011), as well as the composite end points of death/MI (18 h to 24 h: OR = 60.1, 95% CI 7.34 to 492.1, p < 0.0005) shock\MI (post-op: OR = 23.3, 95% Cl = 2.82 to 191.4, p = 0.003; 18 h to 24 h: OR = 37.8, 95% Cl = 4.66 to 307.3, p = 0.001) or death/shock/MI (post-op: OR = 20.0, 9506 CI = 2.81 to 142.0, p = 0.003; 18 h to 24 h: OR = 67.4, 95% Cl = 6.96 to 652.3, p < 0.0005). In contrast, in the presence of TnT, the results of CK-MB measurement added no independent prognostic information. CONCLUSIONS Troponin T is superior to CK-MB for the prediction of impending complications after cardiac surgical procedures. (C) 2002 by the American College of Cardiology Foundation.