Target INR for Warfarin in Atrial Fibrillation with Low Kidney Function and Remote MI

Standard Target INR Range

The European Society of Cardiology recommends that for patients with atrial fibrillation on warfarin, the target INR is 2.0-3.0, regardless of renal function status, to maximize stroke prevention while minimizing bleeding risk 1, 2
The optimal target to aim for within this range is an INR of 2.5, as this maximizes the proportion of time spent in the therapeutic range 2

Patients with severe chronic kidney disease or on dialysis should still target an INR of 2.0-3.0 when warfarin is used for atrial fibrillation 3
The American College of Cardiology states that renal dysfunction does not change the target INR range of 2.0-3.0 for atrial fibrillation, though dose requirements may differ 3

The American College of Cardiology recommends that the remote myocardial infarction does not alter the target INR for atrial fibrillation anticoagulation, and the target INR remains 2.0-3.0 4
When warfarin is indicated for both atrial fibrillation and post-MI indications, the target INR remains 2.0-3.0 4

An INR of 3.6 is above the therapeutic range and associated with increased bleeding risk, particularly intracranial hemorrhage when INR exceeds 3.5, according to the American College of Chest Physicians 2
Warfarin dose should be reduced to bring the INR back into the 2.0-3.0 range 2

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 stable, with more frequent monitoring for patients with renal dysfunction 3
The goal is to maintain time in therapeutic range (TTR) >65-75%, as TTR below this threshold is independently associated with increased risk of adverse events, according to the American College of Chest Physicians 2

The American College of Cardiology recommends that the combination of atrial fibrillation, renal dysfunction, and history of MI places this patient at high risk for both stroke and bleeding, making maintenance of INR within the narrow 2.0-3.0 range critical 5