Isoenzymes of creatine phosphokinase in acute myocardial infarction.

Serial determinations of creatine phosphokinase (CPK) isoenzymes were performed in 400 patients with definite acute myocardial infarction (AMI). The findings were correlated with the clinical course and the findings in another 300 cases of increased CPK levels. MB-CPK, the cardiac fraction, was present in all 400 cases of AMI and in only 5 cases of the 300 patients with high CPK due to causes other than AMI. Based on the magnitude and time course of the total CPK in relation to the MB-CPK, five different patterns are described which correlate with the clinical course. Our findings thus suggest that the determination of CPK isoenzymes can be a most helpful diagnostic tool in the care of the cardiac patient.