Relationship between the enzymatically estimated infarct size and clinical findings in acute myocardial infarction

In 580 patients with a definite myocardial infarction (MI) and no previous MI, the enzymatically estimated infarct size was related to the clinical course including various complications. In all patients, heat-stable lactate dehydrogenase activity (EC 1.1.1.27, LD) was analyzed every 12 hours for 48-108 hours and in a subgroup (n = 170) creatine kinase activity (EC 2.7.3.2, CK) and creatinine kinase subunit B (CK B) were analyzed every 6 hours for 48 hours. The highest recorded enzyme activity was used as a rough estimate of infarct size. A positive correlation was found between serum enzyme activity and most of the clinical variables studied, such as incidence of congestive heart failure, treatment with furosemide, incidence of hypotension, cardiogenic shock, pericarditis, post myocardial infarction syndrome, AV block III, and the duration of hospitalization. We conclude that the enzymatically estimated infarct size determined by heat-stable LD, CK and CK B closely reflects the severity of the infarction.