To define the group of patients at high risk for myocardial infarction (MI) and death associated with abdominal aortic aneurysm repair, resting gated blood pool studies were obtained on 50 such aneurysm patients preoperatively. The results indicated that three groups could be distinguished among these patients by cardiac ejection fraction. Group I (n = 25) had preoperative ejection fractions ranging from 56% to 85%. None of the patients in group I suffered an acute perioperative MI. Group II (n = 20) comprised patients with ejection fractions ranging from 36% to 55%. There was a 20% incidence of MI in group II but no cardiac deaths. Group III included five patients with ejection fractions ranging from 27% to 35%. There was an 80% incidence of perioperative MI in these patients, with one cardiac death and one cardiac arrest. All perioperative MIs occurred within the first 48 hours after surgery. In addition there was a 50% incidence of perioperative MI among all those patients who were 80 years of age or older. These results indicate guidelines for the management of patients undergoing abdominal aortic aneurysm repair based on their preoperative ejection fraction. The data further suggest that the noninvasive gated blood pool method of determining ejection fraction may serve a more broadly useful function in helping to determine which of those patients about to undergo major surgical procedures are at high risk for perioperative MI.