From 1979 to 1985, 109 patients were treated for congestive heart failure caused by postinfarction left ventricular aneurysm. Congestive heart failure was predominant in all patients at the time of diagnosis, 73% of whom were in Functional Class III or IV. Left ventricular end-diastolic pressure averaged 23.8 +/- 0.8 mm Hg (mean +/- standard error of the mean), total ejection fraction 29.7% +/- 1.0%, and telediastolic volume of the aneurysm 76.2 +/- 5.8 ml. Aneurysmectomy was performed in 49 patients (45%), whereas the remaining 60 patients were treated medically. The two groups did not differ in regard to clinical and hemodynamic data on admission, except for a more extensive coronary artery disease in the surgical group. Follow-up was obtained for all patients (100%) and averaged 48 +/- 3 months. Actuarial survival curves were similar, and the 5-year survival rates for surgical and medical groups were 70 +/- 7% and 64% +/- 7%, respectively (not significant). However, the 5-year complication-free rate was significantly (p = 0.05) higher among surgical patients (52% +/- 8%) than among the medical group (31% +/- 7%). Multivariate analysis showed the following variables to influence survival independently (p less than 0.05): contractile segment ejection fraction, right ventricular failure, antecedents of cardiac arrest or cardiogenic shock, and corrected contractile score. Independent variables decreasing the risk of cardiac-related complications and death (p less than 0.05) were as follows: surgical treatment, shorter interval between initial infarction and diagnosis of aneurysm, and absence of right ventricular failure. Functional improvement was directly related to surgical treatment and to residual segment contractile score (p less than 0.05). Thus, in patients with congestive heart failure caused by left ventricular aneurysm, surgical treatment improved the quality of life and prognosis for cardiac-related complications, but did not increase overall survival, compared to medical management of similar patients.