Prediction of long-term survival by preoperative exercise testing in patients with depressed ejection fraction undergoing myocardial revascularization.

Ejection fraction is a major determinant of morbidity and mortality for patients with ischemic heart disease. Patients with an ejection fraction of 0.40 or less are generally recognized as having a poorer prognosis than those patients with an ejection fraction of 0.50 or better and remain a heterogeneous group. It would be useful if patients with a favorable surgical prognosis could be identified preoperatively. Fifty-five patients who underwent coronary artery bypass grafting and had an ejection fraction less than 0.40 (mean of 0.23 +/- 0.07 standard deviation) were studied by catheter measurement of pulmonary arterial pressure and radionuclide left ventriculography. Heart rate, systemic blood pressure, pulmonary artery pressures, cardiac output, and ejection fraction were measured, at rest, after nitroglycerin was given intravenously and with supine bicycle exercise. Forty-seven patients who had follow-up longer than 4 years were divided into two groups according to their life status (alive or dead) 4 years after operation. Measured variables of exercise stress tests and clinical characteristics were entered into factor analysis to obtain a cardiac function factor score for predicting the life status after 4 years. The cardiac function factor score was highly loaded by stroke index (rest, nitroglycerin), cardiac index (exercise), systemic vascular resistance index (exercise), and history of congestive heart failure. The cardiac function factor provided a predictive value superior to that of any individual variable. By dividing the patients into two groups by cardiac function factor score, the actuarial 5-year survival was 72% versus 17% for good and poor prognosis groups, respectively (p < 0.0001). Preoperative exercise stress testing data integrated by factor analysis provide a predictive tool for patients with a low ejection fraction.