Objectives. This study was undertaken to determine which exercise and radionuclide ventriculographic variables predict prognosis in advanced heart failure. Background. Although cardiopulmonary exercise testing is frequently used to predict prognosis in patients with advanced heart failure, little is known about the prognostic significance of ventriculographic variables. Methods. The results of maximal symptom-limited cardiopulmonary exercise testing and first pass radionuclide ventriculography in patients with advanced heart failure referred for evalu tion for cardiac transplantation were analyzed. Results. Sixty seven patients with advanced heart failure (mean [+/-SD]; age 51 +/- 10 years, New York Heart Association functional classes III (58%) and IV (18%); mean left ventricular ejection fraction 0.22 +/- 0.07) underwent simultaneous upright bicycle ergometric cardiopulmonary exercise testing and first-pass rest/exercise radionuclide ventriculography. Mean peak oxygen consumption (Vo(2)) was 11.8 +/- 4.2 ml/kg per min, and mean peak age- and gender-adjusted percent predicted oxygen consumption (%Vo(2)) was 38 +/- 11.9%. Univariate predictors of overall survival included right ventricular ejection fraction greater than or equal to 0.35 at rest and greater than or equal to 0.35 at exercise and %Vo(2), greater than or equal to 45% (all p < 0.05). In a multivariate proportional hazards survival model, right ventricular ejection fraction greater than or equal to 0.35 at exercise (p < 0.01) and %Vo(2) greater than or equal to 45% (p = 0.01) were selected as independent predictors of overall survival. Univariate predictors of event-free survival included right ventricular ejection fraction greater than or equal to 0.35 at rest (p = 0,01) and greater than or equal to 0.35 at exercise (p < 0.01), functional class II (p < 0.05) and %Vo(2) greater than or equal to 45% (p = 0.05). Right ventricular ejection fraction greater than or equal to 0.35 at exercise (p = 0.01) was the only independent predictor of event-free survival in a multivariate proportional hazards model. Cardiac index at rest, Vo(2), left ventricular ejection fraction at rest, and exercise-related increase or decrease >0.05 in left or right ventricular ejection fraction were not predictive of overall or event-free survival in any univariate or multivariate analysis. Conclusions. 1) Right ventricular ejection fraction greater than or equal to 0.35 at rest and exercise is a more potent predictor of survival in advanced heart failure than Vo(2) or %Vo(2); 2) %Vo, rather than Vo(2) predicts survival in advanced heart failure; 3) neither %Vo(2) nor Vo(2) predicts survival to the combined end point of death or admission for inotropic or mechanical support in patients with advanced heart failure.