What is the target International Normalized Ratio (INR) range for patients with mechanical valve replacement?

From the Guidelines

The target International Normalized Ratio (INR) range for patients with mechanical valve replacement should be 2.0-3.0 for aortic valves and 2.5-3.5 for mitral valves, as recommended by the 2020 ACC/AHA guideline for the management of patients with valvular heart disease 1. The goal of INR in patients with mechanical valve replacement is to balance the risks of thromboembolism and bleeding.

• For patients with current-generation mechanical aortic valve prostheses, an INR of 2.5 (range, 2.0–3.0) provides a reasonable balance between the risks of thromboembolism and bleeding 1.
• In patients with an aortic mechanical prosthesis who are at higher risk of thromboembolic complications, the INR should be maintained at 3.0 (range, 2.5–3.5) 1.
• For patients with mechanical mitral valves, an INR target of 3.0 (range, 2.5–3.5) provides a reasonable balance between the risks of under- or over-anticoagulation 1. It is essential to note that the INR target may vary based on individual patient factors, such as the presence of atrial fibrillation, previous thromboembolism, or hypercoagulable state.
• Regular blood testing is necessary to monitor the INR level and adjust the anticoagulation therapy as needed 1.
• Patients should maintain consistent vitamin K intake through diet and avoid missing doses of anticoagulation medication to ensure stable INR levels.
• It is crucial to inform all healthcare providers about this anticoagulation therapy before any procedures to minimize the risk of complications. The 2020 ACC/AHA guideline for the management of patients with valvular heart disease provides evidence-based recommendations for the management of patients with mechanical valve replacement, including the target INR range and anticoagulation therapy 1.

From the FDA Drug Label

For all patients with mechanical prosthetic heart valves, warfarin is recommended. For patients with a St. Jude Medical (St. Paul, MN) bileaflet valve in the aortic position, a target INR of 2.5 (range, 2.0 to 3. 0) is recommended. For patients with tilting disk valves and bileaflet mechanical valves in the mitral position, the 7th ACCP recommends a target INR of 3.0 (range, 2.5 to 3.5). For patients with caged ball or caged disk valves, a target INR of 3.0 (range, 2.5 to 3. 5) in combination with aspirin, 75 to 100 mg/day is recommended.

The goal of INR in patients with mechanical valve replacement is to maintain a target INR range, which varies depending on the type and position of the valve.

• St. Jude Medical bileaflet valve in the aortic position: target INR of 2.5 (range, 2.0 to 3.0) 2
• Tilting disk valves and bileaflet mechanical valves in the mitral position: target INR of 3.0 (range, 2.5 to 3.5) 2
• Caged ball or caged disk valves: target INR of 3.0 (range, 2.5 to 3.5) in combination with aspirin, 75 to 100 mg/day 2

From the Research

Target INR Range for Mechanical Valve Replacement

The target International Normalized Ratio (INR) range for patients with mechanical valve replacement varies depending on the position of the valve and the presence of additional risk factors for thromboembolism.

• For mechanical aortic valve replacement, the recommended INR range is between 2.0 and 3.0 3, or 2.5 to 3.5 for patients with additional risk factors for thromboembolism 4, 5.
• For mechanical mitral valve replacement, the recommended INR range is between 2.5 and 3.5 5, 6.
• Some studies suggest that lower INR targets may be acceptable for certain types of mechanical valves, such as the On-X valve, with an INR range of 1.5 to 2.5 3.

Factors Influencing INR Target Range

The INR target range may be influenced by various factors, including:

• Valve position (aortic or mitral) 5
• Valve type (e.g. On-X valve) 3
• Presence of additional risk factors for thromboembolism (e.g. atrial fibrillation) 4, 5
• Patient age and comorbidities 5

Clinical Evidence

Several studies have investigated the optimal INR target range for patients with mechanical valve replacement, including:

• The ESCAT I and II trials, which demonstrated that anticoagulation self-management can reduce complication rates by maintaining INR levels closer to the target range 7
• The PROACT Mitral trial, which found that low-dose warfarin (target INR 2.0-2.5) was not noninferior to standard-dose warfarin (target INR 2.5-3.5) for patients with mechanical mitral valve replacement 6
• A review of current guidelines and published literature, which suggests that an INR range of 2.5 to 3.5 may be appropriate for patients with mechanical aortic valves and additional risk factors for thromboembolism 3