Natural history six years after acute myocardial infarction. Is there a low-risk group?

One hundred fifty-four survivors of acute myocardial infarction were observed for six years. Patients with anterior lesions had increased mortality in the acute phase of infarction, a trend not sustained during the long-term follow-up period. Recurrent myocardial infarction and intraventricular conduction disturbances were associated with relatively high short-term and long-term mortality. Four groups were defined. The high-risk group had congestive heart failure, major bundle-branch block, previous myocardial infarction, ventricular tachyarrhythmias, or second- or third-degree atrioventricular block. The low-risk group had none of these stigmata. Each category was divided into those under and over the age of 60. Only patients in the low-risk group, over 60 years of age, (24 percent) had a six-year survival comparable to the standard actuarial projections. Thus, 74 percent of the survivors of the acute phase of infarction had a six-year mortality far in excess of the general population. Some were particularly vulnerable during the first year. These findings may warrant reappraisal of the indications for diagnostic and surgical approaches to managing patients after myocardial infarction.