From the Guidelines
The International Normalized Ratio (INR) goal for a bioprosthetic mitral valve is 2.5.
INR Goal for Bioprosthetic Mitral Valve
- The American College of Chest Physicians recommends an INR goal of 2.5 for bioprosthetic mitral valves in the first 3 months after implantation 1.
- The American Heart Association/American College of Cardiology guidelines suggest an INR goal of 2.5 for at least 3 months and up to 6 months after surgical bioprosthetic mitral valve replacement (MVR) in patients at low risk of bleeding 1.
- The evidence supports the use of anticoagulation with a vitamin K antagonist (VKA) to achieve an INR of 2.5 in patients with bioprosthetic mitral valves to reduce the risk of thromboembolism and valve thrombosis.
- Aspirin 75 mg to 100 mg daily is also recommended in addition to anticoagulation with a VKA in patients with a bioprosthetic valve 1.
- The potential benefit of anticoagulation therapy must be weighed against the risk of bleeding, and the decision to extend anticoagulation up to 6 months should be individualized based on the patient's risk factors and clinical presentation.
From the Research
International Normalized Ratio (INR) Goal for Bioprosthetic Mitral Valve
- The INR goal for a bioprosthetic mitral valve is a topic of discussion in several studies 2, 3.
- According to the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy, for patients with bioprosthetic valves in the mitral position, vitamin K antagonists with a target INR of 2.5 (range, 2.0 to 3.0) are recommended for the first 3 months after valve insertion 2.
- Another study suggests that oral anticoagulants at an INR of 2.0 to 2.3 were as effective as an INR of 2.5 to 4.0 and were associated with fewer bleeding complications during the first 3 months after operation in patients with bioprosthetic valves in the mitral position 3.
- There is no direct evidence from the provided studies to support a specific INR goal for bioprosthetic mitral valves beyond the initial 3-month period, but aspirin may reduce the long-term frequency of thromboembolism in patients with bioprosthetic valves 2, 3.
Comparison with Mechanical Valves
- The INR goals for mechanical valves are more established, with a target range of 2.5 to 3.5 for tilting disk valves and bileaflet prosthetic valves in the mitral position 4, 3, 5.
- A study comparing low-dose warfarin (target INR, 2.0-2.5) to standard-dose warfarin (target INR, 2.5-3.5) in patients with mechanical mitral valves found that low-dose warfarin did not achieve noninferiority for the composite primary end point of thromboembolism, valve thrombosis, and bleeding events 5.
Anticoagulation Management
- Anticoagulation management for patients with prosthetic heart valves requires careful monitoring of INR levels to balance the risk of thromboembolism and bleeding complications 6.
- A study of 507 patients with mechanical prosthetic valve replacement found that anticoagulation-related complications, including hemorrhage and thromboembolism, occurred in 3.2% of patients per year, with a mean INR of 2.6 +/- 0.59 and mean warfarin dose of 5.17 +/- 1.6 mg 6.