What is the target International Normalized Ratio (INR) goal for patients with an aortic valve replacement?

INR Goals for Aortic Valve Replacement

For patients with a mechanical aortic valve replacement, the target INR should be 2.5 (range 2.0-3.0) for most patients, while those with additional risk factors for thromboembolism should aim for an INR of 3.0 (range 2.5-3.5). 1

Mechanical Aortic Valve Replacement

Standard Risk Patients

• Target INR: 2.5 (range 2.0-3.0) 1
• This provides optimal balance between preventing thromboembolism while minimizing bleeding risk
• The American College of Cardiology/American Heart Association (ACC/AHA) guidelines strongly recommend this target range for mechanical aortic valves without additional risk factors 1

High-Risk Patients

• Target INR: 3.0 (range 2.5-3.5) 1
• Indicated for patients with additional risk factors:
  • Atrial fibrillation
  • Previous thromboembolism
  • Hypercoagulable state
  • Older-generation prosthesis (e.g., ball-in-cage)
  • Severe left ventricular dysfunction 1

Special Considerations for On-X Valves

• For patients with On-X mechanical aortic valves without risk factors, a lower INR of 1.5-2.0 plus aspirin (75-100 mg daily) may be reasonable starting 3 months after surgery 1, 2
• Recent research shows this reduced anticoagulation level resulted in 57% reduction in the composite endpoint of thromboembolism, valve thrombosis, and major bleeding compared to standard dosing 2

Mechanical Mitral Valve Replacement

• Target INR: 3.0 (range 2.5-3.5) 1
• Higher target due to increased thrombogenicity in the mitral position
• The GELIA study showed lower survival rates with lower INR targets in mitral valve patients 1

Bioprosthetic Aortic Valve Replacement

• Anticoagulation with warfarin (INR 2.0-3.0) is typically recommended only for the first 3 months after valve insertion 3
• After 3 months, antiplatelet therapy with aspirin 75-100 mg daily is usually sufficient 1

Management After Thromboembolic Events

• For mechanical aortic valve patients who experience a stroke or systemic embolic event while in therapeutic range:
  • Increase INR goal from 2.5 to 3.0 (range 2.5-3.5) OR
  • Add daily low-dose aspirin (75-100 mg) after assessing bleeding risk 1

Important Caveats

• Direct oral anticoagulants (DOACs) are contraindicated for mechanical valves 1
• Dabigatran is specifically contraindicated for mechanical valve prostheses 1
• Anti-Xa direct oral anticoagulants have not been assessed and are not recommended for mechanical valves 1
• Antiplatelet therapy alone is insufficient for mechanical valves and carries unacceptable thrombosis risk 1

Monitoring Considerations

• Time in therapeutic range is critical for optimal outcomes
• Studies show patients with target INR 2.0-3.5 stayed in range 74.5% of the time, while those with target 3.0-4.5 were in range only 44.5% of the time 1
• Higher INR targets are associated with increased bleeding risk without significant improvement in thromboembolic protection 4

Recent evidence challenges the higher intensity anticoagulation (INR 3.0) for mechanical AVR patients with additional risk factors, as one study showed increased bleeding without reduction in thromboembolic events 4. However, current guidelines still recommend the higher target for these high-risk patients until more definitive evidence emerges.