1990 Volume 2 Issue 2 Pages 113-119
It is not easy to diagnose acute myocardial infarction (AMI) during the first few hours after the onset, because the indicators for diagnosis, such as electrocardiogram (ECG) and conventional plasma enzymes and isozymes values are within normal ranges. Isoforms of creatine kinase (CK; ATP: creative N-phosphotransferase, EC 2.7.3.2) -MM evolve through posttranslational modification in blood stream from tissue (MM3) to MM2 and MM1. In this study, we quantified changes in CK-MM Isof orm profiles in the first available serum samples from patients with acute myocardial infarction and normal subjects. CK-MM isoform profiles were measured by a specific monoclonal antibody against CK-M (lysine) that contains lysine at the C-terminal residue, and CK-MM isoform index was expressed as CK-M (lysine) /CK-M, having no lysine at the C-terminal residue. In the 114 control subjects, the CK-MM isoform index was 0.56±0.14 (mean±SD), and the upper limit of normal (defined as the mean plus 2SD) was 0.84. In contrast, among the 34 patients with AMI, the index in the first available plasma sample averaged 0.85±0.52 (p<0.01), compared with control subjects. The first available samples were obtained 3.7±2.5 hr after the onset of symptoms. In 13 of 34 patients (38.2%), the index was greater than the normal. Total CK and CK-MB activities were greater than normal in 11 and 10 of 34 patients, respectively. The CK-MM isoform index can be an excellent indicator for early diagnosis of AMI.
