From January 1982 to December 1991, 65 interventions were performed in 61 patients with active infective endocarditis (IE): 32 on native valves (Group 1) and 33 on prosthetic valves (Group 2). In Group 1, 23 patients had a known previous valve disease; major preoperative clinical complications occurred in 16 patients (50%); 84% were in NYHA classes III and IV. In Group 2 major preoperative clinical complications occurred in 13 patients (44.8%); 86% were in NYHA classes III and IV. The mean time interval between the onset of hemodynamic impairment of varying degrees and surgery was 13 +/- 15 days for Group 1, and 8 +/- 11 days for Group 2. In all cases, the native valves or prostheses were replaced by mechanical valve prostheses. Particular procedures were performed in three patients in Group 1 and five patients in Group 2. In Group 1 there were 8 hospital deaths (25%) and 11 (34.4%) non-fatal complications. In Group 2 there were 9 deaths (31%) and 14 (48.3%) non-fatal complications. Risk factors for hospital death were "preoperative low cardiac output syndrome" and "time interval between the onset of cardiac failure and surgery" in Group 1, "cardiac failure+sepsis" in Group 2, "time interval between the onset of cardiac failure and surgery" and "particular procedures" in all 61 patients. Sepsis alone and the type of pathogenic agent does not significantly affect the risk of death. The recurrence of acute IE was 12.6% in Group 1, and 20% in Group 2. The incidence of reintervention was 12.6% in Group 1 and 35% in Group 2.(ABSTRACT TRUNCATED AT 250 WORDS)