Cardiac Troponin T Levels for Risk Stratification in Acute Myocardial Ischemia

Abstract

Background. The prognosis of patients hospitalized with acute myocardial ischemia is quite variable. We examined the value of serum levels of cardiac troponin T, serum creatine kinase MB (CK-MB) levels, and electrocardiographic abnormalities for risk stratification in patients with acute myocardial ischemia. Methods. We studied 855 patients within 12 hours of the onset of symptoms. Cardiac troponin T levels, CK-MB levels, and electrocardiograms were analyzed in a blinded fashion at the core laboratory. We used logistic regression to assess the usefulness of baseline levels of cardiac troponin T and CK-MB and the electrocardiographic category assigned at admission-ST- segment elevation, ST-segment depression, T-wave inversion, or the presence of confounding factors that impair the detection of ischemia (bundle branch block and paced rhythms)-in predicting outcome. Results. On admission, 289 of 801 patients with base-line serum samples had elevated troponin T levels (>.0.1 ng per milliliter). Mortality within 30 days was significantly higher in these patients than in patients with lower levels of troponin T (11.8 percent vs. 3.9 percent, P<0.001). The troponin T level was the variable most strongly related to 30-day mortality (chi-square=21, P<0.001), followed by the electrocardiographic category (chi-square=14, P=0.003) and the CK-MB level (chi-square = 11, P = 0.004). Troponin T levels remained significantly predictive of 30-day mortality in a model that contained the electrocardiographic categories and CK-MB levels (chi-square=9.2, P=0.027). Conclusions. The cardiac troponin T level is a powerful, independent risk marker in patients who present with acute myocardial ischemia. It allows further stratification of risk when combined with standard measures such as electrocardiography and the CK-MB level.