Creatine kinase MB isoforms in patients with skeletal muscle injury: Ramifications for early detection of acute myocardial infarction

We measured total creatine kinase (CK), CK-MB isoen-zyme, and the MB isoforms in 202 serum and plasma samples from nine groups of patients and normal individ-uals: 39 with acute myocardial infarction (Ml), divided according to time between the onset of chest pain and blood collection (1-6 h, 7-12 h, and 13-48 h); 26 with chest pain for whom an Ml was ruled out, sampled at admission; 17 undergoing bypass surgery or cardiac catheterization, sampled within 6 h after either procedure; 1 7 with acute skeletal muscle injury, sampled within 8 h after injury; 30 marathon runners immediately after a race; 17 runners and other athletes>1 2 h after training or a race; 12 with cerebral injury or seizures, sampled at admission; 8 with closed head injury, sampled at admis-sion; and 38 normal subjects. CK-MB (relative index) and MB isoforms (MB/MB1) were respectively increased in 15 % and 75 % of Ml patients 1-6 h after onset, 94 % an