CARDIAC TROPONIN-I RELEASE CORRELATES WITH MYOCARDIAL-INFARCTION SIZE

Cardiac troponin I, creatine kinase, and creatine kinase MB activity w ere tested in serial blood samples from 15 patients with first-lime Q wave acute myocardial infarction (2 anterior and 13 inferior wall infa rctions). All patients received intravenous thrombolytic therapy. Card iac troponin I and creatine kinase MB activity were compared with scin tigraphic estimates of myocardial scar (single photon emission compute d tomography [SPECT] with (99m)Technetium-isonitrile [Tc-sestamibi]) o n late images at rest about 5 weeks after myocardial infarction. Scint igraphic defect sizes ranged from 3.2 to 41.2% (median: 27.3%) of left ventricle. Cardiac troponin I increased and peaked in parallel with c reatine kinase MB activity, and the peak values correlated with each o ther (r = 0.76, p = 0.002). Troponin I stayed increased for several da ys longer than creatine kinase and creatine kinase MB activity. It cou ld be detected at least until the 4th day after admission. Significant correlation coefficients were found between Tc-99m-isonitrile defect sizes and areas under cardiac troponin I curves (r = 0.53, p = 0.042) and between Tc-99m-isonitrile defect sizes and cumulative creatine kin ase MB activity release (r = 0.64, p = 0.01). Animal studies have alre ady shown a very close correlation between histologic infarct size and SPECT Tc-99m-isonitrile defect size. Therefore, our results indicate that cardiac troponin I release in patients with infarct size.