From the Guidelines
The target INR for an On-X valve is between 1.5 and 2.0 [ 1 ]. Aspirin is often recommended in conjunction with warfarin, at a dose of 81-100 mg per day [ 1 ]. The duration of anticoagulation therapy is typically lifelong, but may be adjusted based on patient-specific factors.
Key Considerations
- For patients with a mechanical On-X AVR and no thromboembolic risk factors, a goal INR of 1.5-2.0 may be reasonable starting 3 months after surgery [ 1 ].
- Warfarin dosing is targeted to an INR of 2.5 (range 2.0-3.0) for the first 3 months after surgery [ 1 ].
- Aspirin is recommended in conjunction with warfarin, at a dose of 75-100 mg daily [ 1 ].
- The decision to use anticoagulation therapy should be individualized, taking into account the patient's risk of bleeding and thromboembolism [ 1 ].
Anticoagulation Regimen
- The anticoagulation regimen for patients with an On-X valve should be tailored to their individual risk factors and clinical judgment [ 1 ].
- The use of dual-antiplatelet therapy may be considered in certain situations, but it is not recommended as a standard practice [ 1 ].
- The duration of anticoagulation therapy is typically lifelong, but may be adjusted based on patient-specific factors [ 1 ].
From the Research
Target International Normalized Ratio (INR) for On-X Mechanical Aortic Valve
The target INR for patients with an On-X mechanical aortic valve is a topic of ongoing research. Several studies have investigated the optimal INR range for these patients, with varying results.
- The study by 2 found that an INR range of 1.5-2.0 is safe and effective for patients with an On-X aortic mechanical valve, with a significant reduction in major bleeding and similar rates of thromboembolic events.
- The study by 3 reported a low target INR regimen of 1.5-2.0, with a median INR of 1.92, and found that this regimen resulted in a significantly low risk of bleeding.
- The review by 4 suggested that the INR goal in high-risk On-X aortic valve recipients can be managed at 1.5 to 2.5 with low-dose aspirin 3 months after valve implantation.
- The study by 5 found that an INR range of 1.5-2.0 is safe after mechanical aortic valve replacement with the On-X valve, with a significantly lower risk of bleeding and no significant increase in thromboembolism.
- The review by 6 confirmed that low-dose warfarin (INR 1.5-2.0) is associated with lower major bleeding and no difference in thromboembolic events compared to standard anticoagulation (INR 2.0-3.0) after implantation of On-X aortic prostheses for patients at high risk of thromboembolic events.
Key Findings
- An INR range of 1.5-2.0 is considered safe and effective for patients with an On-X mechanical aortic valve.
- This INR range is associated with a lower risk of bleeding and similar rates of thromboembolic events.
- The use of low-dose aspirin in combination with warfarin may also be beneficial in reducing the risk of bleeding and thromboembolism.