This investigation assesses the prognostic value of radionuclide measurements of cardiac function in patients undergoing coronary artery bypass grafting (CABG). Radionuclide angiograms during exercise and at rest were obtained in 182 patients before (< or = 30 days), early (< or = 3 months), and late (< or = 3 years) after CABG. Cox proportional hazard regression analysis was used to identify independent predictors of 44 cardiac deaths that occurred a median 12 years after bypass. Although the exercise ejection fractions before and early after CABG were significantly related to subsequent cardiac death (chi-square = 10.84, p = 0.001, and chi-square = 7.4, p = 0.006, respectively), the late postoperative exercise ejection fraction was the strongest predictor (chi-square = 13.9, p = 0.0002), contributing above and beyond clinical and catheterization data. These data document the validity of the exercise ejection fraction as an important predictor of cardiac death after CABG and suggest the potential clinical application of serial measurements of the exercise ejection fraction as an important noninvasive adjunct to postoperative evaluation of these patients.