A Comparison of Mechanical Valve Performance in a Poorly Anticoagulated Community

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This study was undertaken to evaluate the clinical performance of the Carbomedics, Medtronic Hall and On-X valves in the challenging setting of a Third World population with incomplete anticoagulation coverage.


In the Carbomedics group 140 valves were implanted in 126 patients (aortic 30, mitral 82, and aortic and mitral 14), 39% were adequately anticoagulated. Follow-up was 89% complete for a total of 216 patient-years. In the Medtronic Hall series 224 valves were implanted in 198 patients (aortic 50, mitral 122, and aortic and mitral 26), 39% were adequately anticoagulated. Follow-up was 93% complete for a total of 459 patient-years. In the On-X series 252 valves were implanted in 200 patients (aortic 44, mitral 104, and aortic and mitral 52), 58% were adequately anticoagulated. Follow-up was 94% complete for a total of 2217 patient-years.


Hospital mortality was 2.4% (3 patients) in the Carbomedics group, 3.9% (9 patients) in the Medtronic Hall group, and 2.0% in the On-X group. None of the hospital deaths were valve-related. The linearized rates for late complications in the mitral position (percent per patient-year) were, respectively, for the Carbomedics (CM), the Medtronic Hall (MH), and On-X valves—thromboembolism: 1.4 (CM), 1.1 (M.H.); 0.0 (On-X); bleeding: 0.0 (CM), 0.4 (MH); 0.0 (On-X); thrombosis: 6.5 (CM), 2.0 (MH); 0.0 (On-X). In the aortic position, the linearized rates of late complications were, respectively—thromboembolism: 0.0 (CM), 1.6 (MH); 2.2 (On-X); bleeding: 1.3 (CM), 1.0 (MH); 0.0 (On-X); thrombosis: 1.3 (CM), 0.0 (MH); 0.0 (On-X).


There were no significant differences in the performance of the three valves in the aortic position. In the mitral position the linearized rate of valve thrombosis was significantly higher in the Carbomedics group (p = 0.002).

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