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A comparison of mechanical valve performance in a poorly anticoagulated community
M A Williams1, L Crause, S Van Riet
1Department of Cardiothoracic Surgery, Provincial Hospital, Port Elizabeth, Republic of South Africa.
Insights
The On-X valve showed superior performance in mitral positions compared to Carbomedics and Medtronic Hall valves, especially in populations with limited anticoagulation. No significant differences were observed in aortic valve performance across the three types.
Area of Science:
- Cardiac Surgery
- Biomaterials Science
- Clinical Performance Evaluation
Background:
- Evaluating mechanical heart valve performance is crucial, particularly in resource-limited settings.
- Incomplete anticoagulation coverage presents unique challenges for valve durability and patient outcomes.
- This study focuses on Carbomedics, Medtronic Hall, and On-X valves in such a demanding environment.
Purpose of the Study:
- To assess the clinical performance of three distinct mechanical heart valve prostheses.
- To compare valve-related complications in patients with suboptimal anticoagulation.
- To identify potential differences in valve thrombosis and thromboembolism rates.
Main Methods:
- Retrospective analysis of patients receiving Carbomedics, Medtronic Hall, or On-X valves.
- Data collection included valve type, position (aortic/mitral), anticoagulation adequacy, and follow-up duration.
- Linearized rates of complications (thromboembolism, bleeding, thrombosis) were calculated and compared.
Main Results:
- Hospital mortality was low across all groups, with no valve-related deaths.
- In the mitral position, Carbomedics valves showed a significantly higher thrombosis rate (6.5%/patient-year) compared to On-X (0.0%/patient-year).
- Aortic valve performance was comparable among the three types, with low rates of major complications.
Conclusions:
- The On-X valve demonstrated superior performance in the mitral position, with a significantly lower thrombosis rate.
- Carbomedics valves exhibited a higher incidence of thrombosis in the mitral position.
- No significant performance differences were noted between the three valve types in the aortic position.
Background:
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.
Methods:
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.
Results:
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).
Conclusions:
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).
