Left and right ventricular performance characteristics in operative candidates with combined aortic and mitral regurgitation (AR/MR) have not been well defined. Therefore, we determined radiomudide cineangiographic ejection fractions, as well as echocardiographic and hemodynamic parameters, in 8 symptomatic patients undergoing double-valve replacement with pure, severe AR/MR. In order to gain insight into the basis for the poor postoperative survival in patients with this intrinsically biventricular disease, we compared these results with those of 29 symptomatic patients with isolated AR and with 18 symptomatic patients with isolated MR, all also undergoing valve replacement. Before operation, patients with AR/MR had significantly lower left ventricular (LV) ejection fraction than patients with MR (rest, 40 ± 9% vs 52 ± 10%, p <0.025; exercise, 35 ± 12% vs 54 ± 12%, p <0.005) and tended to have lower LV ejection fraction than patients with AR alone (rest, 40 ± 9% vs 45 ± 12%, difference not significant; exercise, 35 ± 12% vs 39 ± 11%, difference not significant); right venbiclar (RV) ejection fraction was lower in AR/MR than in AR (p <0.01), and tended to be lower than in MR (difference not significant). At average postoperative follow-up of 72 to 76 months (survivors in each group), symptomatic patients with AR/MR had significantly poorer survival than symptomatic patients with isolated MR (p <0.05) and were more likely to have persistent symptoms than patients with AR (p <0.05). These findings suggest that symptomatic patients with AR/MR have poorer LV and RV performance than similarly symptomatic operative candidates with AR or MR alone. These findings are paralleled by poorer operative outcome, in terms of survival and symptom persistence, in the AR/MR group. © 1990.