Nontransmural myocardial infarction: a comparison of hospital and late clinical course of patients with that of matched patients with transmural anterior and transmural inferior myocardial infarction.

The hospital and long-term course of 67 patients with nontransmural myocardial infarction was compared with that of 66 patients with transmural anterior and 63 patients with transmural inferior infarction matched for age, sex, previous infarction and prior congestive heart failure. During their hospital stay, patients with nontransmural infarction had significantly less congestive heart failure and fewer intraventricular conduction defects than did patients with transmural anterior infarction; fewer atrial tachyarrhythmias and less sinus bradycardia and atrioventricular block than did patients with transmural inferior infarction; and an incidence of hypotension, pericarditis and ventricular irritability similar to that of patients in the other two groups. Patients with nontransmural infarction had a significantly lower coronary care unit mortality rate (9 percent) than that of patients with transmural anterior or transmural inferior infarction (20 and 19 percent, respectively). By 3 months, the mortality rate had risen to 14 percent in patients with nontransmural infarction, but was significantly higher (29 and 27 percent, respectively) in patients with transmural anterior or transmural inferior infarction. Angina was common in all three groups, occurring in more than 50 percent of patients during a mean follow-up period of 28.6 months after hospital discharge. In contrast, the incidence of subsequent myocardial infarction was significantly greater in patients with nontransmural myocardial infarction, occurring in 21 percent at 9 months compared with only 3 percent of patients with transmural anterior (p less than 0.01) and 2 percent of patients with transmural inferior (p less than 0.05) infarction. By 54 months, 57 percent of patients with nontransmural infarction had sustained a new infarction contrasted with only 12 percent of patients with transmural anterior (p less than 0.001) and 22 percent of patients with transmural inferior (p less than 0.01) infarction. Late mortality increased in patients with nontransmural myocardial infarction and, although this group had a significantly better survival rate at 3 months, the overall late mortality of the three groups was comparable. The study suggests that nontransmural myocardial infarction is an unstable ischemic event associated with a great risk of later myocardial infarction and high late mortality rate. A more aggressive diagnostic and therapeutic approach may be warranted in patients with nontransmural myocardial infarction.