What is the target International Normalized Ratio (INR) goal for patients with a mechanical valve?

INR Goals for Mechanical Heart Valves

For patients with mechanical heart valves, the target INR should be 2.5 (range 2.0-3.0) for aortic valve replacements without risk factors and 3.0 (range 2.5-3.5) for mitral valve replacements or aortic valves with risk factors. 1

Target INR Based on Valve Position and Risk Factors

Aortic Mechanical Valves

• INR goal of 2.5 (range 2.0-3.0) for bileaflet or current-generation single tilting disc mechanical aortic valves without additional risk factors 1
• Higher INR goal of 3.0 (range 2.5-3.5) for aortic mechanical valves with additional risk factors including:
  • Atrial fibrillation
  • Previous thromboembolism
  • Hypercoagulable state
  • Older-generation prosthesis (e.g., ball-in-cage)
  • Severe left ventricular dysfunction 1

Mitral Mechanical Valves

• INR goal of 3.0 (range 2.5-3.5) for all mechanical mitral valve replacements 1
• Higher thromboembolism risk in mitral position compared to aortic position necessitates more intensive anticoagulation 1

Special Considerations

Antiplatelet Therapy

• Addition of low-dose aspirin (75-100 mg daily) to VKA therapy may be considered for patients with mechanical valves, especially those with additional risk factors for thromboembolism 1
• The addition of aspirin should be balanced against increased bleeding risk 1

Management After Thromboembolic Events

• For patients with mechanical aortic valve who experience a stroke or systemic embolic event while in therapeutic range, it is reasonable to:

  • Increase INR goal from 2.5 (range 2.0-3.0) to 3.0 (range 2.5-3.5), or
  • Add daily low-dose aspirin (75-100 mg) after assessing bleeding risk 1

• For patients with mechanical mitral valve who experience a stroke or systemic embolic event while in therapeutic range, it is reasonable to:

  • Increase INR goal from 3.0 (range 2.5-3.5) to 4.0 (range 3.5-4.0), or
  • Add daily low-dose aspirin (75-100 mg) after assessing bleeding risk 1

Pitfalls and Caveats

• Fluctuations in INR are associated with increased complications in patients with prosthetic heart valves 1
• Patient compliance may be challenging with higher INR goals - studies show patients with target INR between 2.0-3.5 were within range 74.5% of the time, while those with target INR of 3.0-4.5 were within range only 44.5% of the time 1
• Direct thrombin inhibitors (dabigatran) are contraindicated in patients with mechanical valve prostheses 1
• Anti-Xa direct oral anticoagulants have not been assessed and are not recommended for mechanical valve prostheses 1
• For older-generation mechanical valves (Starr-Edwards valves or mechanical disk valves other than Medtronic Hall), a higher INR target of 2.5-3.5 is recommended even in the aortic position 1

Evidence Quality and Controversies

• Recent research has questioned whether higher intensity anticoagulation (INR goal 3.0) is necessary for mechanical aortic valves with additional risk factors, as it may increase bleeding without reducing thromboembolic events 2
• Some studies suggest that lower INR targets (1.5-2.5) may be safe for specific low-risk patients with bileaflet mechanical aortic valves, but the quality of this evidence is considered low 1, 3
• The FDA label for warfarin aligns with guideline recommendations, supporting an INR of 2.0-3.0 for bileaflet valves in the aortic position and 2.5-3.5 for mitral position valves 4