Surgical results for active endocarditis with prosthetic valve replacement: impact of culture-negative endocarditis on early and late outcomes.

OBJECTIVE: Surgical treatment of active infective endocarditis requires not only hemodynamic repair, but also special emphasis on the eradication of the infectious focus to prevent recurrence. This goal can be achieved by the combination of aggressive debridement of infective tissue and appropriate and adequate antibiotic treatment. We reviewed our experience with active endocarditis and identified factors determining early and late outcomes, particularly focusing on the factor of culture-negative endocarditis.
METHODS: Sixty seven patients with clinical evidence of active endocarditis who underwent operation between 1991 and 2001 were evaluated. The aortic valve was infected in 28 (42%), the mitral valve in 23 (34%), and multiple valves in 16 (24%). Native valve endocarditis was present in 58 (87%) and prosthetic valve endocarditis in 9 (13%). Mean follow-up was 5.7 years (range, 0.2-11.5 years).
RESULTS: Microorganisms were detected in 46 (69%): Staphylococcus aureus in 9 (13%), other staphylococci in 9 (13%), streptococcus species in 19 (28%), and others in 9 (28%), whereas 21 (31%) patients had culture-negative endocarditis. Operative mortality was 17.8% (12 patients). Reoperation was required in 8 (12%), while 3 late deaths (5.5% of hospital survivors) occurred. All events, including death, reoperation, periprosthetic leak, and recurrence of infection, occurred within 2 years after operation. Actuarial freedom from reoperation, late survival, and events at 5 years were 81.6, 76.4, and 68.6%, respectively. On multivariate analysis, no independent adverse predictor was detected for hospital death, whereas the following independent adverse predictors were identified: preoperative heart failure (P=0.0375), prosthetic valve endocarditis (P=0.0391) and culture-negative endocarditis (P=0.0354) for poor late survival; culture-negative endocarditis (P=0.0354) and annular abscess (P=0066) for poor event-free survival. Freedom from events was similar between patients with Staphylococcus aureus infection (3-year freedom 55.6%) and culture-negative endocarditis (3-year freedom 47.6%), whereas events were significantly low in patients with streptococcus infection (3-year freedom 100%).
CONCLUSIONS: In our analysis, no independent adverse predictor was detected for hospital death; however, culture-negative endocarditis was identified as an independent predictor for both late survival and events after surgery. Event-free survivals were similar between staphylococcus infection and culture-negative endocarditis, and all events occurred within 2 years after operation, suggesting the necessity of close follow-up during that period.