From the Guidelines
Anticoagulation therapy is strongly indicated for all patients with a history of valve thrombosis to prevent recurrence, with lifelong warfarin therapy recommended for mechanical heart valves and warfarin with a target INR of 2.0-3.0 for at least 3-6 months for bioprosthetic valves. For mechanical heart valves, the target INR should be 2.5-3.5, with higher targets for mitral or multiple valve replacements 1. Direct oral anticoagulants (DOACs) like apixaban and rivaroxaban are contraindicated for mechanical valves 1. The rationale for anticoagulation is that patients with previous valve thrombosis have demonstrated a hypercoagulable tendency, and the artificial valve surface provides a nidus for thrombus formation, particularly with mechanical valves where blood flow is disrupted by the valve components. Bridging therapy with unfractionated heparin or low-molecular-weight heparin is necessary during warfarin initiation or interruption, and regular INR monitoring is essential, initially weekly then monthly once stable 1.
Some key points to consider in the management of patients with valve thrombosis include:
- The type of valve prosthesis, with mechanical valves requiring lifelong anticoagulation and bioprosthetic valves potentially requiring anticoagulation for a limited period 1
- The presence of risk factors for thromboembolism, such as atrial fibrillation, previous thromboembolism, or hypercoagulable conditions, which may necessitate higher target INR values or more intensive anticoagulation regimens 1
- The risk of bleeding, which must be carefully weighed against the benefits of anticoagulation therapy, particularly in patients with bioprosthetic valves or those at high risk of bleeding complications 1
- The potential role of antiplatelet therapy, such as aspirin, in patients with bioprosthetic valves or those at low risk of bleeding, although the addition of dual-antiplatelet therapy can significantly increase the risk of bleeding complications 1.
Overall, the management of patients with valve thrombosis requires careful consideration of the individual patient's risk factors, valve type, and overall clinical context, with a focus on minimizing the risk of recurrent thrombosis and bleeding complications while optimizing quality of life.
From the FDA Drug Label
For patients with AF and prosthetic heart valves, anticoagulation with oral warfarin should be used; the target INR may be increased and aspirin added depending on valve type and position, and on patient factors. Mechanical and Bioprosthetic Heart Valves For all patients with mechanical prosthetic heart valves, warfarin is recommended.
La indicación para el uso de anticoagulación en pacientes con prótesis valvular y trombosis valvular previa es la anticoagulación con warfarina. El objetivo es prevenir la formación de nuevos trombos y reducir el riesgo de embolia sistémica.
- La dosis de warfarina debe ser ajustada para mantener un INR dentro del rango terapéutico recomendado, que puede variar dependiendo del tipo y posición de la válvula, así como de los factores de riesgo del paciente.
- La anticoagulación con warfarina es recomendada para todos los pacientes con prótesis valvulares mecánicas.
- La duración de la terapia anticoagulante debe ser individualizada y continuada hasta que el riesgo de trombosis y embolia haya pasado 2, 2.
From the Research
Indication for Anticoagulation in Patients with Previous Valve Thrombosis
The indication for anticoagulation in patients with previous valve thrombosis is to prevent further thromboembolic events. According to the studies, anticoagulation therapy is essential for patients with mechanical heart valves, as they have a high risk of thrombus formation on the valve and subsequent systemic embolism 3, 4, 5.
Recommended Anticoagulation Regimens
- For mechanical heart valves, anticoagulation with Warfarin at an INR range of 2-3 for patients with a bileaflet mechanical valve in the aortic position, and an INR of 2.5-3.5 for patients with a mechanical valve in the mitral position 4.
- For patients with a mechanical valve and a history of systemic embolization, an INR of 2.5-3.5 combined with low-dose aspirin (80-100 mg) is recommended 4.
- The American College of Chest Physicians recommends anticoagulation with Warfarin at an INR range of 2.0 to 3.0 for patients with an On-X mechanical aortic valve 6.
Importance of Anticoagulation
Anticoagulation therapy is crucial in preventing valve thrombosis and valve-related thromboembolism in patients with mechanical heart valves 3, 6, 5. The adequacy of warfarin anticoagulation is the most important factor affecting thrombotic and bleeding complications in patients with mechanical valves 7.
Special Considerations
- For patients with bioprosthetic heart valves, heparin is followed by oral anticoagulation for 3 months after mitral or aortic valve replacement, and indefinitely after mitral valve replacement if there is atrial fibrillation or a very large left atrium 5.
- Aspirin may be recommended indefinitely after aortic valve replacement 5.
- Antithrombotic therapy is also considered for special situations such as noncardiac surgery, prosthetic valve endocarditis, anticoagulation after a thromboembolic event, and antithrombotic therapy during pregnancy 5.