What anticoagulant is recommended for patients with mechanical heart valves?

Anticoagulation for Mechanical Heart Valve Patients

For patients with mechanical heart valves, warfarin (vitamin K antagonist) is the only recommended anticoagulant, with specific INR targets based on valve position and risk factors. 1

Anticoagulation Regimen by Valve Position

Mechanical Aortic Valve

• Target INR 2.5 (range 2.0-3.0) for:

  • Bileaflet mechanical valves
  • Medtronic Hall valves
  • No additional risk factors 1, 2

• Target INR 3.0 (range 2.5-3.5) for:

  • Additional risk factors (AF, previous thromboembolism, LV dysfunction, hypercoagulable conditions)
  • Older-generation mechanical valves (ball-in-cage valves) 1, 2

Mechanical Mitral Valve

• Target INR 3.0 (range 2.5-3.5) for all mechanical mitral valves 1, 2

Dual Mechanical Valves (Aortic and Mitral)

• Target INR 3.0 (range 2.5-3.5) 1

Additional Antithrombotic Therapy

• Add low-dose aspirin (75-100 mg daily) to warfarin therapy for all patients with mechanical valves (Class IIa, Level of Evidence: A) 1
• Use caution with aspirin in patients with increased bleeding risk (e.g., history of GI bleeding) 1

Important Considerations

Novel Oral Anticoagulants (NOACs)

• NOACs (direct thrombin inhibitors, factor Xa inhibitors) are contraindicated in patients with mechanical heart valves (Class III: Harm) 1
• The RE-ALIGN trial showed increased thromboembolic and bleeding complications with dabigatran compared to warfarin in patients with mechanical heart valves 1

Bridging Therapy

• For patients requiring temporary interruption of warfarin for procedures:
  • Low-risk patients (bileaflet mechanical AVR without risk factors): Stop warfarin 48-72h before procedure, restart within 24h after procedure
  • High-risk patients (any mechanical MVR or AVR with risk factors): Use therapeutic UFH when INR falls below 2.0 1

Monitoring

• INR should be monitored at least weekly during initiation of therapy
• Once stable, INR should be monitored at least monthly 1
• Home INR monitoring may be considered for suitable patients 3

Clinical Pitfalls to Avoid

1. Never use NOACs for mechanical valves - The RE-ALIGN trial demonstrated increased thromboembolic and bleeding complications with dabigatran compared to warfarin 1

2. Don't underanticoagulate mitral valves - Mechanical mitral valves have higher thromboembolic risk than aortic valves and require higher INR targets 1, 4

3. Don't forget aspirin - The addition of low-dose aspirin (75-100 mg) to warfarin therapy is recommended for all patients with mechanical valves to further reduce thromboembolic risk 1

4. Recognize higher-risk patients - Patients with older valve designs, previous thromboembolism, atrial fibrillation, or LV dysfunction require more intensive anticoagulation 1, 2

5. Careful monitoring during initiation - The first few days and months after valve insertion carry higher embolic risk before the valve is fully endothelialized 1

While recent research has explored lower INR targets for specific valve types (e.g., On-X aortic valves) 5, current guidelines still recommend the standard INR targets outlined above for most mechanical valves to optimize protection against thromboembolism while minimizing bleeding risk.