Target INR for Paroxysmal Atrial Fibrillation on Coumadin

Standard Target Range

The American College of Cardiology recommends a target INR of 2.0 to 3.0 for patients with paroxysmal atrial fibrillation on warfarin, with an optimal target of 2.5 to maximize stroke protection while minimizing bleeding risk 1, 2, 4
The target INR range of 2.0 to 3.0 provides maximum protection against ischemic stroke, whereas lower ranges provide only approximately 80% of the efficacy 1, 2
The American Heart Association and European Society of Cardiology guidelines state that the target INR of 2.0 to 3.0 applies to all patterns of atrial fibrillation, without distinction 3

The American College of Cardiology and American Heart Association guidelines recommend an INR of 2.5, with a target range of 2.0 to 3.0, for primary prevention in most AF patients under age 75 years and for secondary prevention 1, 2
Adjusted-dose warfarin, with an INR of 2.0-3.0, is significantly more effective than low-dose warfarin in preventing thrombotic events, although the specific relative risk reduction is not provided in the relevant citation 1, 2

For patients older than 75 years who are at high risk of bleeding, a target INR of 2.0 may be considered, although this provides incomplete stroke protection 1, 2

The American College of Chest Physicians recommends that time in therapeutic range (TTR) should ideally be ≥65-70%, with optimal control at ≥70% 4, 5
If TTR is consistently below 65%, additional measures such as more frequent INR testing and review of medication adherence should be implemented 4, 5

The American College of Cardiology recommends that INR should be checked at least weekly during warfarin initiation and dose adjustments, and at least monthly once anticoagulation is stable 3

The American College of Chest Physicians states that the conventional INR target of 2.0 to 3.0 should be employed globally, without routine use of lower INR targets 4
INR values above 3.5 are associated with increased bleeding risk, although the specific citation provides limited information on this topic 6