Target INR Levels for Patients on Warfarin Therapy

General INR Target Ranges by Condition

The American College of Cardiology recommends a target International Normalized Ratio (INR) of 2.0 to 3.0 for most patients on warfarin therapy, with specific conditions requiring higher targets of 2.5 to 3.5 1
For patients with non-valvular atrial fibrillation, the American College of Cardiology recommends a target INR of 2.0 to 3.0 2
For mechanical aortic valves, the American Heart Association recommends an INR of 2.5 to 3.5 3, 4
For mechanical mitral valves, the American Heart Association recommends an INR of 2.5 to 3.5 3, 4
For patients with mechanical prosthetic heart valves who experience thromboembolism despite adequate anticoagulation, the American Heart Association recommends a target INR of 2.5 to 3.5 plus aspirin 75-100 mg/day 4
For bioprosthetic aortic or mitral valves with risk factors, the American Heart Association recommends an INR of 2.0 to 3.0 3

The American College of Cardiology recommends weekly INR monitoring during initiation of therapy 2
The American College of Cardiology recommends at least monthly INR monitoring when anticoagulation is stable 2, 5
Elderly patients (>75 years) may require lower warfarin doses due to increased sensitivity 5
Subtherapeutic INR (<2.0) increases thromboembolism risk, while supratherapeutic INR (>3.0 or >3.5 depending on indication) increases bleeding risk without additional antithrombotic benefit 1, 5