What are the implications for a patient on Coumadin (warfarin) for paroxysmal atrial fibrillation (paf) with a subtherapeutic International Normalized Ratio (INR) of 1.9, undergoing a planned procedure in two days?

From the Guidelines

For a patient on Coumadin (warfarin) for paroxysmal atrial fibrillation with an INR of 1.9 and a planned procedure in two days, I recommend proceeding with the procedure without interrupting the Coumadin, as suggested by the most recent guidelines 1. An INR of 1.9 is very close to the therapeutic range (typically 2.0-3.0) for atrial fibrillation and is acceptable for most procedures. The slight difference between 1.9 and 2.0 is clinically insignificant and does not substantially increase thrombotic risk. For the procedure itself, local hemostatic measures should be used as needed, including pressure, topical hemostatic agents, or suturing. If the procedure is high-bleeding risk (such as neurosurgery, major abdominal surgery, or cardiac surgery), consultation with the proceduralist is warranted to determine if temporary Coumadin interruption is necessary. In such cases, bridging with low molecular weight heparin might be considered depending on the patient's stroke risk, as outlined in the 2024 AHA/ACC/ACS/ASNC/HRS/SCA/SCCT/SCMR/SVM guideline for perioperative cardiovascular management for noncardiac surgery 1. Following the procedure, the patient should continue their regular Coumadin dosing schedule with INR monitoring within 3-5 days to ensure maintenance of therapeutic levels. This approach balances the risk of thromboembolism from atrial fibrillation against the risk of procedural bleeding, and is in line with the recommendations from the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 2 and the 2014 AHA/ACC guideline for the management of patients with valvular heart disease 3. Key considerations include:

• The patient's stroke risk, as assessed by the CHA2DS2-VASc score 2
• The type of procedure and its associated bleeding risk 1
• The need for bridging anticoagulation, if any 3
• The importance of regular INR monitoring to ensure therapeutic anticoagulation levels 2

From the FDA Drug Label

The dose of warfarin should be adjusted to maintain a target INR of 2.5 (INR range, 2.0 to 3.0) for all treatment durations. Oral anticoagulation therapy with warfarin is recommended in patients with persistent or paroxysmal AF (PAF) (intermittent AF) at high risk of stroke

The patient's current INR is 1.9, which is below the target range of 2.0-3.0. The warfarin dose may need to be adjusted to achieve a therapeutic INR before the planned procedure in two days. It is recommended to consult the patient's healthcare provider to determine the best course of action. 4

From the Research

Patient on Coumadin for Atrial Fibrillation with INR of 1.9

• The patient has an INR of 1.9, which is below the therapeutic range for atrial fibrillation, indicating that the patient may be at risk for thromboembolic events 5.
• The patient is scheduled for a procedure in two days, which may require interruption of warfarin therapy.

Bridging Anticoagulation Therapy

• A standardized periprocedural anticoagulation regimen with low-molecular-weight heparin (LMWH) can be used to bridge the patient during the interruption of warfarin therapy 6.
• LMWH has been shown to be effective and safe in preventing thromboembolic events in patients with atrial fibrillation who require temporary interruption of warfarin therapy 6, 7, 8.
• The use of LMWH as bridging therapy has been associated with a low risk of thromboembolic and major bleeding complications 6, 8.

Management of Warfarin Therapy

• Warfarin therapy should be managed carefully to avoid excessive anticoagulation, which can increase the risk of bleeding complications 5.
• The patient's INR should be monitored frequently to ensure that it remains within the therapeutic range 5.
• If the patient's INR is too high, vitamin K1 can be administered to reverse the anticoagulant effect of warfarin 5.

Procedure-Related Bleeding Risk

• The risk of bleeding complications during and after the procedure should be assessed, and the use of LMWH as bridging therapy should be tailored to the individual patient's risk factors 9, 8.
• Patients with a high risk of bleeding complications may require a more cautious approach to bridging anticoagulation therapy, such as the use of unfractionated heparin (UFH) instead of LMWH 9, 8.