What is the target International Normalized Ratio (INR) for a patient with a porcine (pig) valve?

From the Guidelines

The goal INR for patients with pork (porcine) heart valves is typically 2.0-3.0 for the first three months after implantation, after which many patients can be transitioned to aspirin therapy alone. This approach is based on the most recent guidelines, which prioritize minimizing the risk of thromboembolism while also considering the potential risks associated with long-term anticoagulation therapy 1. The decision to use anticoagulation therapy and the target INR range should be individualized based on the patient's specific risk factors and clinical circumstances, including the presence of conditions such as atrial fibrillation. Key considerations include:

• The type and position of the valve
• The patient's comorbidities
• The risk of thromboembolism and bleeding
• The patient's ability to tolerate long-term anticoagulation therapy According to the 2024 ACC/AHA clinical performance and quality measures for adults with valvular and structural heart disease, anticoagulation with a VKA is protective against valve thrombosis and thromboembolic events, but the specific target INR range should be determined on a case-by-case basis 1. It is essential to note that bioprosthetic valves, such as pork valves, have a lower risk of thromboembolism compared to mechanical valves, which is why they do not generally require lifelong anticoagulation 1. However, the specific anticoagulation regimen should always be determined by the patient's cardiologist based on individual risk factors and clinical circumstances. In general, the target INR range for bioprosthetic valves is lower than for mechanical valves, and aspirin therapy alone may be sufficient after the initial period of anticoagulation 1. Ultimately, the goal is to minimize the risk of thromboembolism and bleeding while also considering the patient's quality of life and ability to tolerate long-term anticoagulation therapy.

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 goal INR for a patient with a bioprosthetic pork valve is not explicitly stated, but for bioprosthetic valves in general, a target INR of 2.5 (range, 2.0 to 3.0) is recommended for valves in the mitral position and suggested for valves in the aortic position for the first 3 months after valve insertion 2.

From the Research

INR Goal for Pork Valve

• The optimal INR goal for patients with mechanical heart valves is still a topic of debate, with different studies suggesting different target ranges 3, 4, 5.
• For patients with mechanical aortic valves, an INR goal of 2 to 3 is recommended for low-risk patients, while a goal of 2.5 to 3.5 is recommended for high-risk patients 4.
• For patients with mechanical mitral valves, an INR goal of 2.5 to 3.5 is recommended for new generation prosthetic valves, while a goal of 3.5 to 4.5 is recommended for older types of valves 5.
• The use of non-vitamin K antagonist oral anticoagulants (NOACs) in patients with bioprosthetic valves or prior surgical valve repair is also being explored, with studies suggesting that NOACs may be an effective and safe treatment strategy for these patients 6.
• The risks and benefits of short-term anticoagulation in patients receiving bioprosthetic aortic valves have been debated, with studies suggesting that aspirin plus warfarin may be associated with a reduced risk of death and embolic events, but at the cost of an increased bleeding risk 7.

Key Findings

• The ESCAT I study found that anticoagulation self-management after mechanical heart valve replacement decreased complication rates by maintaining INR levels closer to the target range 3.
• The ESCAT II study found that lowering the target range for INR self-management may further reduce complication rates 3.
• A study published in the Journal of pharmacy practice found that the INR goal for patients with mechanical aortic valves should be 2 to 3 for low-risk patients and 2.5 to 3.5 for high-risk patients 4.
• A study published in Interactive cardiovascular and thoracic surgery found that the optimal target INR for warfarin therapy in patients with prosthetic mechanical mitral heart valves is 2.5-3.5 5.