Prosthetic valve endocarditis: analysis of risk factors for mortality

Between 1975 and 1990, 70 episodes of prosthetic valve endocarditis (PVE) were diagnosed in 65 patients at Leiden University Hospital. The overall mortality rate was 27%. Antecedent endocarditis attributable to the same micro-organism (mortality 63%, P = 0.02) and Staphylococcus aureus as the causative micro-organism (mortality 100%, P = 0.001) were significant predictors for mortality. Sex, type and position of the valve and therapy had no significant influence on the mortality. All patients infected with S. aureus died, irrespective of whether they received medical treatment alone or in combination with surgery. None of the patients with streption, endocarditis had abscesses at reoperation; the mortality rate for this group was 14%. Abscess formation, especially in aortic valves, was the most important finding at reoperation and corresponded with a mortality rate of 55%. Ring abscesses occurred equally in patients with mechanical and bioprosthetic valves. Seven of the 15 patients (47%) with significant prosthetic valve dehiscence died. In patients with mitral valve endocarditis, localized dehiscence of the valve was observed. In conclusion a previous endocarditis attributable to the same micro-organism and the causative micro-organism (S. aureus) were important risk factors for mortality due to PVE.