Although pulmonary congestion during acute myocardial infarction (AMI) is recognized as an important adverse event, the detailed clinical features, natural history and predictive value of standard diagnostic tests in such patients have not been well characterized. As part of a multicenter prospective postinfarction trial, 123 patients with pulmonary congestion during AMI, who survived and were discharged from the coronary care unit, were studied. These patients were compared with similar patients who did not develop pulmonary congestion. Patients with pulmonary congestion had a significantly higher 1-year mortality rate compared with 744 patients without pulmonary congestion during AMI (28 vs 5.5%). Patients with pulmonary congestion were characterized by a lower ejection fraction, more frequent anterior infarction, diminished ability to perform exercise testing and higher incidence of subsequent cardiac events. Even without these variables, pulmonary congestion was associated with increased mortality. In patients with pulmonary congestion, ejection fraction (dichotomized at 30%) and exercise testing were the most discriminating tests in risk stratification. An ejection fraction greater than 30% and completion of the exercise test was associated with a 7% mortality while an ejection fraction less than 30% and inability to take or complete the exercise test was associated with a 44% 1-year mortality. A greater incidence of reinfarction, ischemia during exercise and ischemic events at the time of death in the pulmonary congestion group suggests that ischemia may be an important factor in this high risk category.