Bioprosthetic Valve Endocarditis: Indicators for Surgical Intervention

Among 1,000 patients with bioprosthetic valves, there were 20 cases of bacterial endocarditis. Eleven patients (Group 1) died or had surgery performed. Nine patients (45%) (Group 2) were sterilized by medical treatment alone. The main features of the patients cured with antibiotics were infection by streptococci, normal two-dimensional echocardiograms, and normal hemodynamic function of the valve prosthesis. Patients in Group 1, on the other hand, had more aggressive bacterial or fungal infections, thickening of the leaflets or masses present in the two-dimensional echocardiographic study, and severe transprosthetic gradients at cardiac catheterization. Valves recovered in Group 2 (3 patients) revealed normal macroscopic and histopathological findings, while in Group 1 (11 patients), all patients showed severe obstruction of the bioprosthesis (mainly from thrombotic vegetations filling the valve cusps), severe destruction of the bioprosthesis with collagen breakdown, infiltration by acute inflammatory cells, and secondary calcification. Only 3 of these patients also showed spread of perivalvular infection into the host tissue. The presence of any clinical, two-dimensional echocardiographic, or hemodynamic sign of bioprosthetic stenosis should prompt urgent operation to prevent sudden death or quick downhill cardiac failure. Obstruction of a bioprosthesis in the presence of infection is a sign of endocarditis that cannot be cured by medical treatment alone. Two-dimensional echocardiography is a highly reliable and noninvasive means of discovering valve changes.