International Normalized Ratio (INR) Targets: Atrial Fibrillation and Flutter

International Normalized Ratio (INR) Targets: Atrial Fibrillation and Flutter

The international normalized ratio (INR) recommendations below are per guidelines from 2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation.^[1]

The term “nonvalvular AF is no longer used.
Exclusion criteria for CHADS-VASc assessment and use of NOACs are now defined as moderate to severe mitral stenosis or a mechanical heart valve.
In patients with AF, anticoagulant therapy should be individualized on the basis of shared decision-making after discussion of the absolute risks and relative risks of stroke and bleeding, as well as the patient’s values and preferences.
NOACs (dabigatran, rivaroxaban, apixaban, and edoxaban) are recommended over warfarin in NOAC-eligible patients with AF/Flutter (except with moderate-to-severe mitral stenosis or a mechanical heart valve).
Among patients treated with warfarin, the international normalized ratio (INR) should be determined at least weekly during initiation of anticoagulant therapy and at least monthly when anticoagulation (INR in range) is stable.
For patients with AF or atrial flutter of 48 hours duration or longer, or when the duration of AF is unknown, anticoagulation with warfarin (INR 2.0-3.0), is recommended for at least 3 weeks before and at least 4 weeks after cardioversion.
For patients with AF or atrial flutter of less than 48 hours’ duration with a CHA2DS2-VASc score of 2 or greater in men and 3 or greater in women, administration of heparin, a factor Xa inhibitor, or a direct thrombin inhibitor is reasonable as soon as possible before cardioversion, followed by long-term anticoagulation with warfarin (INR 2.0-3.0) is recommended.
For patients with AF or atrial flutter and an elevated CHA2DS2-VASc score of 2 or greater in men or 3 or greater in women, anticoagulation with warfarin (INR 2.0-3.0), is recommended.
For patients with AF or atrial flutter and moderate-to-severe mitral stenosis regardless CHA2DS2-VASc score anticoagulation with warfarin (INR 2.0-3.0), is recommended.
For patients with AF or atrial flutter who have mechanical heart valves, warfarin is recommended regardless of CHA2DS2-VASc score, and the target international normalized ratio (INR) intensity (2.0-3.0 or 2.5-3.5) should be based on the type and location of the prosthesis.
For patients with AF or atrial flutter and hypertrophic cardiomyopathy (HCM) regardless CHA2DS2-VASc score, anticoagulation with warfarin (INR 2.0-3.0), is recommended.
In patients with AF/Flutter and end-stage CKD or on dialysis with elevated CHA2DS2-VASc score of 2 or greater in men or 3 or greater in women, the direct thrombin inhibitor dabigatran or the factor Xa inhibitors rivaroxaban or edoxaban are not recommended because of the lack of evidence from clinical trials that benefit exceeds risk; therefore, warfarin (INR 2.0-3.0), is recommended.

AF/Flutter after cardiac surgery^{[2, 3]}:

For patients with multiple episodes of AF or one episode that lasts more than 24 to 48 hours, we recommend the initiation of oral anticoagulant therapy, but only if bleeding risks are considered acceptable. As the role of direct thrombin and factor Xa inhibitors has not been established for patients with postoperative AF, we suggest that warfarin be chosen for most patients (International normalized ratio 2.0-3.0)
We suggest continuing anticoagulation for at least 4 weeks after return to sinus rhythm, particularly if the patient has risk factors for thromboembolism. Longer duration of anticoagulation is recommended by some of our experts in patients with high CHA ₂DS ₂-VASc scores, at low risk for bleeding based on the HAS-BLED, or at high risk of AF recurrence.
Consider long-term anticoagulation for patients who remain in AF or who have paroxysmal AF at 4 weeks.
We suggest maintaining oral anticoagulation in patients in which a concomitant Cox-Maze procedure has been performed for at least 3 months, regardless of no postoperative atrial arrhythmias. After 3 months with no AF recurrence, anticoagulation may be interrupted, considering the patient risk profile for stroke by the CHA ₂DS ₂-VASc score.

* CHA2DS2-VASc Score: (Congestive heart failure, Hypertension, Age ≥75 years [doubled], Diabetes mellitus, Prior Stroke or TIA or thromboembolism [doubled], Vascular disease, Age 65 to 74 years, Sex category)