From the Guidelines
Anticoagulation for patients with mechanical heart valves who have liver failure with abnormal INR should be managed with a vitamin K antagonist (VKA) at an INR goal appropriate for the comorbidity of the patient and the type and position of the mechanical valve prosthesis, with close monitoring of INR levels due to the potential for fluctuations in INR in patients with liver failure 1.
Key Considerations
- The type and position of the mechanical valve prosthesis play a crucial role in determining the INR goal, with aortic mechanical prostheses typically requiring an INR of 2.5 (range, 2.0–3.0) and mitral mechanical valves requiring an INR of 3.0 (range, 2.5–3.5) 1.
- Liver failure can compromise vitamin K-dependent clotting factor production, making VKA management challenging, but VKAs are still the preferred choice for anticoagulation in patients with mechanical heart valves 1.
- Close monitoring of INR levels is essential, as fluctuations in INR are associated with an increased incidence of complications in patients with prosthetic heart valves 1.
Management Approach
- For patients with aortic mechanical prostheses, an INR goal of 2.5 (range, 2.0–3.0) is recommended, while for patients with mitral mechanical valves, an INR goal of 3.0 (range, 2.5–3.5) is recommended 1.
- Regular monitoring of INR levels should be performed, with frequency determined by clinical stability, to minimize the risk of thromboembolic events and bleeding complications.
- Hematology consultation is strongly advised for these complex cases, and platelet counts should be monitored regularly due to the risk of heparin-induced thrombocytopenia, although heparin is not the preferred choice for anticoagulation in these patients.
From the Research
Anticoagulation Management for Mechanical Heart Valves
- The American College of Chest Physicians recommends anticoagulation with Warfarin at an INR range of 2-3 for patients with a bileaflet mechanical valve in the aortic position, and an INR of 2.5-3.5 for patients with a mechanical valve in the mitral position 2.
- For patients with a mechanical valve and a history of systemic embolization, an INR of 2.5-3.5 combined with low-dose aspirin (80-100 mg) is recommended 2.
- In patients with liver failure and abnormal INR, the use of direct oral anticoagulants (DOACs) such as factor Xa inhibitors may be considered as an alternative to vitamin K antagonists (VKAs) 3.
- A pilot study found that rivaroxaban 20 mg once daily was safe and effective in patients with mechanical aortic heart valves, with no thromboembolic or bleeding events observed 4.
Alternative Anticoagulation Options
- Low molecular weight heparin (LMWH) may be used as a temporary anticoagulation option in patients with mechanical heart valves, with a systematic review and meta-analysis finding no differences in the risk of thromboembolic or major bleeding events compared to unfractionated heparin (UFH) or VKAs 5.
- The use of LMWHs in patients with mechanical heart valves is not approved, but may be considered in certain clinical settings, such as in patients with liver failure and abnormal INR.
Monitoring and Management
- Regular monitoring of INR levels is crucial in patients with mechanical heart valves, with a target INR range of 2-3 for most patients 2.
- The time in therapeutic range (TTR) is an important factor in determining the risk of complications in patients with mechanical heart valves, with a TTR of 83% or higher associated with the best outcomes 6.