Relationship between electrocardiographically estimated infarct size and morbidity during a two-year follow-up.

In 587 patients with a first myocardial infarction (MI) the electrocardiographically (ECG) estimated infarct size was related to morbidity during a two-year follow-up. Patients with transmural MI (Q- or R-wave changes in standard ECG) were more often treated for heart failure and returned to work less frequently than patients with subendocardial MI (ST-T-wave changes only). There were trends indicating a higher reinfarction rate in patients with subendocardial MI, whereas angina pectoris was observed as frequently in both groups. In a subset of patients with anterior MI, infarct size was estimated from the total Q- and R-wave amplitude in 24 precordial leads 4 days after arrival in hospital. A positive relationship was observed between ECG-estimated infarct size and treatment for heart failure, and patients with smaller infarctions according to ECG criteria returned to work less frequently. A higher reinfarction rate was observed in patients with smaller infarctions. In patients with inferior MI there were mostly weaker correlations between ECG-estimated infarct size (Q- and R-wave changes in leads II, III, and a VF) and morbidity during the two-year follow-up.