DIFFERENT TIME COURSES OF CARDIAC CONTRACTILE PROTEINS AFTER ACUTE MYOCARDIAL-INFARCTION

For the first time we have compared time courses of cardiac myosin lig ht chain-1 (MLC-1), beta-type myosin heavy chain (MHC), troponin T (Tn T), myoglobin, creatine kinase (CK) and CKMB in the same patients with acute myocardial infarction (AMI). Blood samples were serially collec ted in 23 patients with first-time AMI. All but 3 patients received in travenous thrombolytic treatment. TnT and MLC-1 time courses were biph asic in most patients and showed two distinct peaks in 13 and 8 patien ts, respectively. MHC time courses were usually monophasic, Only 1 pat ient showed a biphasic MHC time course with two distinct peak values. Although MHC and MLC were lower by about the fourth day after onset of AMI in early reperfused patients, reperfusion did not qualitatively a lter MLC and MHC release (no significant influence on the first appear ance in blood or on time to peak). MLC and MHC peaks correlated closel y (r = 0.75, P = 0.0001), whereas TnT peaks were correlated less close ly with MLC or MHC peaks (r = 0.58 each, P < 0.007). Peak values of al l cardiac contractile proteins correlated closely and significantly wi th CKMB peaks (0.75 less than or equal to r less than or equal to 0.81 , P less than or equal to 0.0006). Myoglobin was the first marker to i ncrease in blood after AMI and showed the earliest peaks, whereas MHC increased latest showing the latest peaks. TnT increased significantly (P = 0.0001) earlier than MLC and MHC. These results can be explained by the impact of the intracellular compartmentation of a cardiac prot ein on the rapidity with which it is released after AMI.