Relationship between enzymatically estimated infarct size and short- and long-term survival after acute myocardial infarction.

In 585 patients with acute myocardial infarction (AMI) and no previous MI the maximal activity of serum heat-stable lactate dehydrogenase (LD) (EC 1.1.1.27) activity was related to 1-year and 2-year mortality rates. All patients participated in a double-blind trial with metoprolol during the first three months after an AMI. Thereafter both groups were treated in a similar way. A strong relationship was found between LD maximum activity and the in-hospital prognosis (p less than 0.001), the 1-year survival rate (p less than 0.001) and the 2-year survival rate (p less than 0.001). When the patients who were alive after primary hospitalization were analyzed as a separate group, the relationship between LD maximum activity and 1-year and 2-year survival rates remained (p less than 0.001). In a subsample of 171 patients the maximal activity of creatine kinase (CK) (EC 2.7.3.2) and CK subunit B did not correlate either with in-hospital, 1-year or 2-year survival rates. We conclude that, when a sufficiently large number of patients are investigated, there is a strong relationship between serum enzyme maximum activity and short- and long-term survival.