Myoglobin, creatine kinase MB isoforms and creatine kinase MB mass in early diagnosis of myocardial infarction in patients with acute chest pain

Objectives: Measurements of myoglobin and creatine kinase (CK)-MB isoforms have been suggested to be sensitive tests for the early diagnosis of myocardial infarction (MI). We have investigated, the utility of myoglobin, creatine kinase (CK)-MB isoforms and creatine kinase MB mass (CK-MBm) in early diagnosis of MI using cardiac troponin T (cTnT) positivity as a reference. Design and Methods: The study population comprised 440 patients who had had chest p-am for less than 12 h. Patients were divided into cTnT negative (cTnT-) or cTnT positive (cTnT+) patients (concentration (if cTnT >0.1 mug/L at two different time points during 72 h). Results: At the time of admission to the emergency department receiver operating characteristics (ROC) curves of CK-MB isoforms and CK-MBm were not better than that of myoglobin. Six hours after admission CK-MB isoforms and CK-MBm, provided statistically significantly larger areas under the curve (AUC) than myoglobin (p < 0.01). When ROC curves were related to the onset of chest pain (< 3 h, 3-6 h, and > 6 h) there were no significant differences between the cardiac markers studied. Conclusions: According to the present findings, CK-MB isoforms or myoglobin offer no advantage over CK-MBm ass early markers of myocardial infarction. (C) 2002 The Canadian Society of Clinical Chemists. All rights reserved.