The Role of Risk Stratification in the Early Management of a Myocardial Infarction

Abstract

To review the literature on early management of myocardial infarction. Papers published or referenced in major English-language cardiology journals for the last 15 years. Large recent multicenter studies and the guidelines for early management of patients with acute myocardial infarction (American College of Cardiology/American Heart Association Task Force) were emphasized. A strategy for risk stratification was developed from information available in the emergency department, from the first days of the hospitalization, and before discharge to identify patients in whom intervention might improve prognosis. Treatment of myocardial infarction requires establishing patency of the infarct-related artery, usually with thrombolysis. Risk stratification begins in the emergency department (phase 1) using clinical (primarily the electrocardiogram) and historical data to identify patients at risk for massive infarction. For patients at highest risk, the efficacy of thrombolytic therapy must be assured and, if not effective, emergency angiography and mechanical reperfusion should be considered. During days 2 to 5, (phase 2), patients with large amounts of ischemic myocardium, postinfarction angina, "flash" pulmonary edema, or anterior non-Q infarctions are identified and studied. Predischarge (phase 3) stratification identifies those patients at risk for early death. A previous infarction, an ejection fraction less than 0.40, pulmonary congestion during the hospitalization, delayed afterpotentials on signal-averaged electrocardiography, symptomatic ventricular ectopic beats, decreased heart rate variability, limited exercise tolerance, or ischemia on exercise testing identifies patients at high risk. Patients with jeopardized myocardium must be identified for revascularization to try to improve survival. More data are needed to determine whether angioplasty or bypass surgery will improve prognosis in these patients.