What is the anticoagulation protocol for porcine (bioprosthetic) mitral valve replacement?

From the Guidelines

Patients with porcine mitral valve replacements should be treated with anticoagulation using a vitamin K antagonist (VKA) to achieve an INR of 2.5 for at least 3 months after surgical replacement, followed by lifelong aspirin therapy (75-100 mg daily) in the absence of other indications for oral anticoagulants. This approach is based on the recommendations from the 2020 ACC/AHA guideline for the management of patients with valvular heart disease 1. The guideline suggests that for patients with a bioprosthetic mitral valve replacement, aspirin 75 to 100 mg daily is reasonable in the absence of other indications for oral anticoagulants 1.

The initial 3-month period after surgery is critical, as the valve tissue is undergoing endothelialization and carries a higher risk of thrombus formation. Anticoagulation with a VKA during this period helps to mitigate this risk. After 3 months, the risk of thromboembolism decreases significantly for bioprosthetic valves, making long-term anticoagulation unnecessary for most patients. However, patients with additional risk factors for thromboembolism, such as atrial fibrillation, previous thromboembolism, left ventricular dysfunction, or hypercoagulable states, should continue warfarin indefinitely 1.

Regular monitoring is essential, especially during the initial anticoagulation period, with INR checks every 1-2 weeks until stable, then monthly. Patients should be educated about bleeding risks, medication interactions, and the importance of consistent vitamin K intake while on warfarin. The use of direct oral anticoagulants, such as dabigatran, is contraindicated in patients with mechanical valve prostheses 1.

Key considerations for managing patients with porcine mitral valve replacements include:

• Anticoagulation with a VKA for at least 3 months after surgery
• Lifelong aspirin therapy (75-100 mg daily) in the absence of other indications for oral anticoagulants
• Regular monitoring of INR and bleeding risks
• Patient education on medication interactions and consistent vitamin K intake
• Avoidance of direct oral anticoagulants in patients with mechanical valve prostheses.

From the FDA Drug Label

For patients with bioprosthetic valves, warfarin therapy with a target INR of 2.5 (range, 2.0 to 3.0) is recommended for valves in the mitral position and is suggested for valves in the aortic position for the first 3 months after valve insertion. The anticoagulation for porcine mitral valve replacement is warfarin therapy with a target INR of 2.5 (range, 2.0 to 3.0), as it is a type of bioprosthetic valve in the mitral position 2. Key points:

• The target INR range is 2.0 to 3.0.
• Warfarin therapy is recommended.
• This recommendation is for bioprosthetic valves in the mitral position.

From the Research

Anticoagulation in Porcine Mitral Valve Replacement

• The use of anticoagulation in patients with porcine mitral valve replacement has been studied to prevent thromboembolic complications 3.
• A study published in 1982 found that aspirin was as effective as Coumadin in preventing thromboembolic events in patients with porcine bioprosthesis, with a lower rate of hemorrhagic complications 3.
• Another study published in 1988 compared the long-term results of three commonly used mitral valve prostheses, including porcine bioprosthesis, and found that bioprostheses were associated with a lower rate of thromboembolic events, minimizing the need for long-term anticoagulation 4.

Alternative Anticoagulation Therapies

• A study published in 2008 explored the use of aspirin and clopidogrel as an alternative to warfarin for thromboprophylaxis in mechanical heart valves, using a swine model, and found that dual-antiplatelet therapy was effective in preventing thrombus formation 5.
• The study suggested that combination aspirin and clopidogrel could be a potential alternative to warfarin in patients with mechanical valves, although further human trials are needed 5.

Patient Selection for Porcine Mitral Valve Replacement

• A study published in 1994 discussed the indications for mitral valve replacement, including the choice of valve prosthesis, and found that bioprosthetic valves were suitable for older patients, patients with contraindications to anticoagulation, and young females desirous of future pregnancy 6.
• The study also found that patient age and presence of coronary artery disease may alter the indications for mechanical or tissue valves, with mechanical prostheses being more suitable for patients without coronary disease in their 60s and 70s 6.