COMPARISON OF CARDIAC TROPONIN-I, CREATINE KINASE-MB, AND MYOGLOBIN FOR DETECTION OF ACUTE ISCHEMIC MYOCARDIAL INJURY IN A SWINE MODEL

To study the comparative value of the levels of cardiac troponin I (cT nI), creatine kinase-MB isoenzyme (CK-MB), and myoglobin in the detect ion of acute ischemic myocardial injury; we serially measured plasma c oncentrations of these cardiac proteins in 12 pigs with myocardial isc hemia subtending severe coronary artery stenoses and in 5 pigs with a sham operation performed but without coronary artery stenosis. In the stenosis group, flow in the left anterior descending (LAD) artery was reduced by 36% and maintained for 24 hours (n = 3), 7 days (n = 6), or 4 weeks (n = 3). Flow in the coronary artery was measured by a flowme ter and regional left ventricular dysfunction was monitored by echocar diography. Myocardial infarction was identified with triphenyltetrazol ium chloride staining. All pigs with stenosis of the LAD had significa nt ultrastructural abnormalities consisting of loss of myofibrils and an increase in mitochondria and glycogen deposition. Cardiac proteins were released in all pigs with stenosis of the LAD artery during the d evelopment of myocardial ischemia; the levels of cTnI, CK-MB, and myog lobin increased significantly, relative to the baseline. The sensitivi ty and specificity for cTnI were higher than for CK-MB or myoglobin. R esults of this study, show that cTnI is the better marker for the dete ction of acute ischemic myocardial injury. Increased levels of cTnI ca n be found in reversible and irreversible myocardial ischemic injury i n this model.