Target INR for Patients with Rheumatic Heart Disease Taking Warfarin
For patients with rheumatic heart disease (RHD) taking warfarin, the target INR should be 2.5 with a range of 2.0-3.0, regardless of whether atrial fibrillation is present. 1
Evidence-Based Recommendations
- For patients with rheumatic mitral valve disease, whether or not atrial fibrillation is present, long-term warfarin therapy with a target INR of 2.5 (range 2.0-3.0) is recommended 1
- This recommendation has a Class IIa level of evidence C according to American Heart Association/American Stroke Association guidelines, indicating that the weight of evidence is in favor of usefulness/efficacy 1
- The target INR range of 2.0-3.0 is consistently recommended across multiple guidelines for patients with rheumatic mitral valve disease 1, 2
Monitoring Considerations
- The safety and effectiveness of warfarin therapy depends critically on maintaining the INR within the therapeutic range of 2.0-3.0 1
- Time in therapeutic range (TTR) is an important measure of anticoagulation quality; patients should aim for TTR >65% to ensure optimal protection 1
- More frequent INR monitoring is recommended when initiating therapy (2-3 times weekly initially), then gradually reducing to every 4 weeks once stability is achieved 1
Special Considerations
- Antiplatelet agents should not be routinely added to warfarin therapy in patients with RHD to avoid additional bleeding risk 1
- For patients with RHD who have a recurrent embolism while receiving warfarin at therapeutic INR, adding low-dose aspirin (81 mg/day) may be indicated 1
- The risk of bleeding increases exponentially when INR exceeds 5.0, making close monitoring essential 3
Comparison with Other Valve Conditions
- The target INR for RHD (2.0-3.0) is lower than that recommended for mechanical prosthetic heart valves, which typically require an INR of 2.5-3.5 1
- This difference reflects the relatively lower thrombogenic risk of native rheumatic valves compared to mechanical prostheses 2
Clinical Outcomes
- Maintaining the INR within the recommended range of 2.0-3.0 is associated with reduced risk of both thromboembolic events and bleeding complications 4
- Subtherapeutic anticoagulation (INR <2.0) significantly increases the risk of thromboembolism and ischemic stroke 1, 5
- INR values >3.0 are associated with a greater incidence of major bleeding, especially intracranial hemorrhage when the INR rises above 3.5 1
Common Pitfalls to Avoid
- Targeting lower INR ranges (e.g., 1.5-2.0) is not supported by strong evidence and may lead to inadequate protection against thromboembolism 1
- Inconsistent vitamin K intake through diet can cause fluctuations in INR values, making it important to maintain consistent dietary habits 1
- Drug interactions can significantly alter warfarin metabolism and effect, requiring more frequent monitoring when starting or stopping other medications 1, 6
By maintaining the target INR of 2.5 (range 2.0-3.0) for patients with RHD on warfarin therapy, clinicians can optimize the balance between preventing thromboembolic events and minimizing bleeding risk.