Direct Oral Anticoagulants Are Contraindicated in Patients with Mechanical Heart Valves
Direct oral anticoagulants (DOACs) are contraindicated in patients with mechanical heart valves and should not be used for anticoagulation in this population. Vitamin K antagonists (VKAs) such as warfarin remain the only appropriate oral anticoagulation therapy for patients with mechanical heart valves.
Evidence Against DOACs in Mechanical Heart Valves
- The 2020 ACC/AHA guideline explicitly states that "for patients with a mechanical valve prosthesis, anticoagulation with the direct thrombin inhibitor, dabigatran, is contraindicated" (Class III: Harm; Level of Evidence: B-R) 1
- Similarly, the guidelines state that "for patients with a mechanical valve prosthesis, the use of anti-Xa direct oral anticoagulants has not been assessed and is not recommended" (Class III: Harm; Level of Evidence: C-EO) 1
- The FDA label for dabigatran (Pradaxa) explicitly contraindicates its use in all patients with mechanical prosthetic valves 2
- The FDA label for rivaroxaban (Xarelto) states that its safety and efficacy have not been studied in patients with prosthetic heart valves other than TAVR, and its use is not recommended in patients with prosthetic heart valves 3
Clinical Trial Evidence
- The RE-ALIGN trial showed an increase in thromboembolic and bleeding complications with dabigatran compared to warfarin in patients with mechanical heart valves, leading to early termination of the trial 1
- Recent data from the PROACT Xa trial comparing apixaban with warfarin in patients with On-X mechanical aortic valves further supports the superiority of VKAs over DOACs for this indication 4
Appropriate Anticoagulation for Mechanical Heart Valves
- All patients with mechanical valves require lifelong anticoagulation with a VKA to decrease the incidence of thromboembolism and associated morbidity 1
- For patients with a mechanical aortic valve replacement (bileaflet or current-generation single tilting disc) without risk factors for thromboembolism, VKA therapy with a target INR of 2.5 (range 2.0-3.0) is recommended 1
- For patients with a mechanical aortic valve replacement with additional risk factors (AF, previous thromboembolism, LV dysfunction, or hypercoagulable conditions) or an older-generation mechanical valve, a higher target INR of 3.0 (range 2.5-3.5) is recommended 1
- For patients with a mechanical mitral valve replacement, anticoagulation with a VKA to achieve an INR of 3.0 (range 2.5-3.5) is indicated 1
Monitoring and Management Considerations
- Regular INR monitoring is essential for patients with mechanical valves on VKA therapy 1
- For patients with mechanical heart valves who experience a stroke or systemic embolic event while in therapeutic range on VKA anticoagulation, it is reasonable to increase the INR goal or add daily low-dose aspirin (75-100 mg), with assessment of bleeding risk 1
- The addition of low-dose aspirin (75-100 mg daily) to VKA therapy may be considered in patients with a mechanical valve who are at low risk of bleeding 1
- For patients with a mechanical On-X AVR and no thromboembolic risk factors, a lower INR target (1.5-2.0) may be reasonable starting ≥3 months after surgery, with continuation of aspirin 75-100 mg daily 1
Special Considerations
- For patients with mechanical heart valves undergoing minor procedures where bleeding is easily controlled (e.g., dental extractions, cataract removal), continuation of VKA anticoagulation with a therapeutic INR is recommended 1
- Bridging anticoagulation therapy during interruption of VKA therapy should be individualized based on valve type, position, and patient risk factors 1
- Patients with mechanical heart valves require careful monitoring of INR and dose adjustments to maintain stable anticoagulation 5
In conclusion, despite the advantages of DOACs in other clinical scenarios requiring anticoagulation, VKAs remain the cornerstone of therapy for patients with mechanical valve prostheses, and DOACs should not be used in this population.