CARDIAC TROPONIN-T RELEASE IN ACUTE MYOCARDIAL-INFARCTION IS ASSOCIATED WITH SCINTIGRAPHIC ESTIMATES OF MYOCARDIAL SCAR

Background: This study compared clinical-chemical estimates of infarct size with scintigraphic estimates of myocardial scar in patients with first-time acute myocardial infarction (AMI). Methods: Levels of the Cardiac isoform of the contractile protein troponin T (TnT), of creati ne kinase (CK), and of the isoenzyme MB of CK (CK MB) were tested in s erially drawn blood samples from 21 patients (two females and 19 males ; median age, 55 years). Of these 21 patients, five had anterior- and 16 had inferior-wall AMI; all patients received intravenous thrombolyt ic therapy. Single-photon emission computed tomography (SPECT) with te chnetium-99m-isonitrile (Tc-sestamibi) was performed at rest after the onset of AMI (median time, 5 weeks). Scintigraphic defects were calcu lated using ''bull's-eye'' polar coordinate maps. All patients had an uncomplicated course between discharge and myocardial scintigraphy. Re sults: Scintigraphic defect sizes ranged from 3.2% to 47.8% of the lef t ventricle (median, 27.3%). Cardiac TnT and CK MB release correlated closely with each other and with scintigraphic estimates of myocardial scar. Significant correlates were found between cardiac TnT and CK MB peak values (r = 0.87, P = 0.0001), CK MB peaks and Tc-sestamibi defe ct sizes (r = 0.73, P = 0.0014), and TnT peaks and scintigraphic defec t sizes (r = 0.73, P = 0.0011). Conclusions: Because animal studies ha ve already shown a very close correlation between histologic infarct s ize and SPECT Tc-sestamibi defect size, our results indicate that card iac TnT is a useful marker to assess infarct size noninvasively in man .