Target INR Ranges for Warfarin Therapy

Standard INR Targets by Clinical Indication

The American Geriatrics Society recommends a target INR range of 2.0-3.0 for most indications, including atrial fibrillation, deep vein thrombosis, and pulmonary embolism 2, 3
The American Geriatrics Society suggests a higher target INR range of 2.5-3.5 for mechanical heart valves and post-myocardial infarction patients with high embolic risk 3
For patients with dilated cardiomyopathy, the target INR range is 2.0-3.0 4
For patients with valvular heart disease and atrial fibrillation, the target INR range is 2.0-3.0 3, 4
For patients with rheumatic mitral valve disease and a history of embolism, the target INR range is 2.0-3.0 4
For patients with bioprosthetic heart valves, the target INR range is 2.0-3.0 for the first 3 months after insertion 3

The American Geriatrics Society recommends daily INR testing until steady state is achieved, then 2-3 times weekly for 1-2 weeks, and weekly for 1 month 2, 5
For patients with consistently stable INRs, testing frequency can be extended up to 12 weeks 6
For single out-of-range INR of ±0.5 from target, the American Geriatrics Society recommends continuing the current dose and retesting within 1-2 weeks 6
For INR <5.0 without bleeding, the American Geriatrics Society recommends withholding warfarin and observing 2, 7
For INR 5.0-9.0 without bleeding, the American Geriatrics Society recommends withholding warfarin, monitoring INR, and resuming at a lower dose 2, 7

The American College of Cardiology notes that INR values below 2.0 are associated with increased thromboembolism risk 8
The American College of Cardiology also notes that INR values above the upper limit of therapeutic range sharply increase bleeding risk 8
Failing to increase monitoring frequency during diet changes, medication changes, or intercurrent illness can lead to poor INR control 2, 5
Overlooking the need for more frequent monitoring after dose adjustments can also lead to poor INR control 2