Natural history of myocardial infarction and its prodromal syndromes

Angiographic studies have shown that the severity of obstructive coronary artery disease is a major facor determining mortality in patients with coronary artery disease. The symptomatic presentation of patients with coronary artery disease appears to be less important in determining survival than the extent of coronary artery narrowing. The extent of left ventricular dysfunction is a second major factor that determines survival. The extent of myocardial damage is also important in determining survival in patients with acute myocardial infarction. Infarct extension has been found to be a frequent occurrence in patients with acute anterior transmural infarction. Since infarct extension often occurs several days after hospital admission, an opportunity may exist to apply therapeutic interventions prophylactically to prevent or limit this additional myocardial loss. To limit the extent of myocardial damage that results from infarction may also help to reduce the frequency of ventricular arrhythmias that occur in the second week after infarction, since these arrhythmias are associated with relatively high peak CPK values and a low left ventricular ejection fraction. Studies in patients with acute nontransmural infarction suggest that infarct size may not be the major factor that affects long term survival but other factors, possibly the extent of coronary artery narrowing, may be important. Although in-hospital mortality following acute infarction may have been altered over the past decade by coronary care units, there is little to suggest that prehospital or late mortality following hospital discharge have been altered. If overall mortality associated with infarction is to be reduced, therapeutic interventions to reduce both the extent of myocardial damage and extent or effect of severe coronary artery narrowing will have to be more vigorously applied in the future.