Troponin-T and CK MB (Mass) in early diagnosis of ischemic myocardial injury. The Helsingborg study, 1992

Abstract

We evaluated cardiac troponin T (S-troponin T) versus CK MB in serum (S-CK MB) sampled 4, 10, 16, and 22 h after onset of acute symptoms in 207 consecutive cases admitted to our coronary care unit in Helsingborg, Sweden, May–October 1992. These were primarily classified into 106 acute myocardial infarctions (AMI) and 101 NOT-AMI cases by conventional cardiological criteria plus S-CK MB (mass). Time curves of S-troponin T and S-CK MB data were plotted for each individual case. Twelve of the 101 cases in the NOT-AMI group showed increased S-troponin T indicating ischemic myocardial injuries. The same cases also showed changes of S-CK MB (mass), though below its discriminator. Seven of these cases were reclassified as minor myocardial damage, constituting 25% of our 28 cases of unstable angina. The remaining five cases showed a combination of constantly increased S-troponin T and decreasing or low S-CK MB mass values as seen after a recent infarction. Consequently, the patient material was reclassified into 118 cases of ischemic myocardial injury (106 conventional AMI + 7 minor myocardial damage + 5 postinfarctions) and 89 cases of NOT-ischemic myocardial injury. The frequency distributions of the maximal S-troponin T and S-CK MB (mass) values of each case were plotted in double test evaluation histograms. For troponin T, discriminator 0.20 μg/L, clinical sensitivity for ischemic myocardial injury was 97% and specificity 99%. With a lower discriminator of 0.10 μg/L, sensitivity increased to 99% and specificity decreased to 89%. For S-CK MB (mass), discriminator 10 μg/L, sensitivity was 91%, specificity 98%. With a lower discriminator of 5 μg/L sensitivity increased to 96% and specificity decreased to 78%. We conclude that as a single routine test, S-troponin T is the marker of choice for early diagnosis of ischemic myocardial damage. The combination S-troponin T and S-CK MB (mass) provides additional, detailed information in reinforction and postinfarction unstable angina pectoris.