Relationship between serum enzyme activity in acute myocardial infarction and morbidity during a 2-year follow-up.

In 585 patients with a first myocardial infarction the enzymatically estimated infarct size was related to the clinical course during a 2-year follow-up. Infarct size was estimated from maximum heat-stable lactate dehydrogenase activity. A higher maximum serum activity was associated with a higher mortality rate, more treatment with diuretics, digitalis and antiarrhythmics and a lower frequency of return to work. Patients with smaller infarcts according to maximum serum activity, however, had a higher incidence of angina pectoris and a higher reinfarction rate. We conclude that although there is a strong association between serum enzyme activity and mortality during a 2-year follow-up, the relation with morbidity appears to be more complex.