Valve Replacement for Prosthetic Valve Endocarditis Due to Staphylococcus aureus
Synopsis: Valve replacement was associated with improved survival in a retrospective analysis of patients with endocarditis of prosthetic cardiac valves due to Staphylococcus aureus.
Source: John MDV, et al. Staphylococcus aureus prosthetic valve endocarditis: Optimal management and risk factors for death. Clin Infect Dis 1998;26:1302-1309.
John and colleagues reviewed the course of 33 patients with prosthetic valve endocarditis due to Staphylococcus aureus seen between 1975 and 1995 at Massachusetts General Hospital. Twenty-two patients had mechanical valves and 11 had bioprostheses. Eighteen patients had aortic valve endocarditis alone, 14 had mitral valve endocarditis, and one patient had infection of prostheses at both positions.
Two-thirds of the patients, including nine who had cardiac abscesses, had cardiac complications of endocarditis; the remainder had worsening valve function, congestive heart failure, or EKG alterations. One-third had CNS complications, including cerebral hemorrhage, mycotic aneurysm, emboli, and abscess. Fourteen (42%) of the patients underwent valve replacement during antibiotic therapy for endocarditis. Fourteen (42%) of the total died within the three-month interval following the diagnosis of endocarditis.
The median duration of antibiotic therapy was 42 days in those who did not undergo surgery and 48 days in those who did. The median duration of antibiotic therapy prior to surgery was 19 days (range, 6-53). Seventy three percent of patients received an aminoglycoside in addition to a beta lactam or vancomycin and one-third also received rifampin. Only two infections were due to methicillin-resistant S. aureus.
Multivariate analysis identified the presence of a cardiac complication of infection as a risk factor for death (OR 13.7; P = 0.02), while valve replacement was protective (OR 0.0; P = 0.004). CNS complications were not an independent risk factor.
COMMENT BY STAN DERESINSKI, MD, FACP
Replacement of cardiac valves, whether native or prosthetic, in the face of active endocarditis is clearly and urgently indicated in the face of complications such as congestive heart failure, valve dysfunction, infection involving the annulus or myocardium, persistent bacteremia, recurrent emboli, early onset infection, and infection with certain organisms such as gram-negative bacilli and fungi. However, it has been suggested by some that the presence of prosthetic valve endocarditis, when caused by virulent organisms such as S. aureus, is in itself an indication for valve replacement.
Several years ago, Yu and colleagues evaluated the outcome of 74 patients with prosthetic valve endocarditis in a prospective multicenter observational study (Yu VL, Fang GD, et al. Ann Thorac Surg 1994;58:1073-1077; Deresinski S. Infect Dis Alert 1994;14(5):33-34). They similarly concluded that valve replacement was associated with a reduced mortality and that this was especially true in the 15 patients with S. aureus endocarditis.
Nonetheless, since not all patients treated medically die, operating on all patients with S. aureus prosthetic valve endocarditis would unnecessarily subject a number of them to surgery. Furthermore, although John et al attempted to correct for severity of illness, this is problematical in a retrospective analysis. In addition, although survival was not reported to improve in a statistically significant manner over time, one wonders about the relevance of patients treated in the late 1970s as opposed to those undergoing current methods of medical and surgical management.
Notwithstanding these concerns, in the absence of more robust data, it behooves the clinician caring for a patient with S. aureus prosthetic valve endocarditis to err on the side of early valve replacement. Clearly, in some patients, such surgery is life saving.
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