Prosthetic valve endocarditis. Analysis of factors affecting outcome of therapy.

We analyzed the outcome of 116 patients with prosthetic valve endocarditis treated between 1975 and 1983 and used multivariate analysis to identify risk factors for in-hospital mortality and bad outcome during follow-up. Complicated prosthetic valve endocarditis was defined as the presence of a new or changing heart murmur, new or worsening heart failure, new or progressive cardiac conduction abnormalities, or prolonged fever during therapy. Complicated prosthetic valve endocarditis was present in 64% of patients; factors associated with complicated prosthetic valve endocarditis included aortic valve infection (odds ratio 4.3, p = 0.002) and onset of endocarditis within 12 months of the cardiac operation (odds ratio 5.5, p = 0.0001). The in-hospital mortality rate for prosthetic valve endocarditis was 23%; patients with complicated prosthetic valve endocarditis had a higher mortality than patients with uncomplicated infection (odds ratio 6.4, p = 0.0009). Combined medical-surgical therapy was used in 39% of patients; surgical therapy was more common in patients with complicated prosthetic valve endocarditis (odds ratio 16, p less than 0.0001) and in patients infected with coagulase-negative staphylococci (odds ratio 3.9, p = 0.003). Survival after initially successful therapy for prosthetic valve endocarditis was adversely affected by the presence of moderate or severe congestive heart failure at hospital discharge (p = 0.03). Bad outcome during follow-up (death, relapse of prosthetic valve endocarditis, or subsequent cardiac operation related to sequelae of the original infection) was more common in the medical than the medical-surgical therapy group (p = 0.02). The difference in long-term outcome between patients treated initially with medical or with medical-surgical therapy was particularly evident in those with complicated prosthetic valve endocarditis (p = 0.008). The presence of complicated prosthetic valve endocarditis is a central variable in assessing prognosis and planning therapy; the majority of patients with complicated prosthetic valve endocarditis are best treated with medical-surgical therapy. Those who are not treated surgically during their initial hospitalization are at high risk for progressive prosthesis dysfunction and require careful follow-up.