Should INR (International Normalized Ratio) be monitored until therapeutic in patients receiving a biventricular ICD (Implantable Cardioverter-Defibrillator) on warfarin (Coumadin) to minimize the risk of pocket hematoma?

INR Monitoring for Biventricular ICD Patients on Warfarin

For patients receiving a biventricular ICD while on warfarin, the INR should be monitored until therapeutic to minimize pocket hematoma risk, with continuation of warfarin during the procedure rather than interruption and bridging. 1

Evidence-Based Recommendations

The 2022 American College of Chest Physicians (ACCP) guidelines provide strong evidence supporting the continuation of warfarin therapy during cardiac device implantation procedures. This recommendation is based on high-quality evidence showing significantly lower rates of pocket hematoma when warfarin is continued versus interrupted with bridging therapy.

Key Points from Clinical Trials:

• The BRUISE CONTROL trial demonstrated that clinically significant pocket hematoma occurred in only 3.5% of patients in the warfarin continuation group compared to 16.0% in the warfarin interruption-bridging group (RR = 0.19; 95% CI: 0.10-0.36) 1
• Meta-analyses of observational studies showed similarly low (2-6%) rates of pocket hematomas when warfarin was continued during pacemaker/ICD implantation 1

Monitoring Protocol for Biventricular ICD Implantation

Pre-Procedure:

1. Check INR within 24 hours before the procedure
2. Ensure INR is <3.0 before proceeding with device implantation 1
3. Continue warfarin at the patient's usual dose without interruption

Post-Procedure:

1. Monitor INR daily until stable
2. Once stable, check INR 2-3 times weekly for 1-2 weeks
3. Then weekly for 1 month
4. Finally, every 1-2 months if stability is maintained 1

Pocket Hematoma Risk Assessment

Research shows that the risk of pocket hematoma is significantly higher with dual antiplatelet therapy (DAPT) than with warfarin alone:

• Hematoma formation occurs in approximately 3.5% of patients on warfarin during device implantation 2
• Patients on DAPT (aspirin + clopidogrel) have a significantly higher risk of hematoma formation compared to those on warfarin alone (P<0.0001) 3
• Pocket revision for hematoma evacuation is needed more frequently in patients on DAPT than those on warfarin alone 3

Important Considerations and Pitfalls

Pitfalls to Avoid:

• Do not interrupt warfarin and bridge with heparin - this approach increases bleeding risk significantly (16% vs 3.5% hematoma rate) 1
• Do not proceed with implantation if INR >3.0 - higher INR values correlate with increased bleeding risk 1, 4
• Do not overlook medication interactions that may affect INR stability during the post-procedure period 1

Special Considerations:

• More frequent monitoring is indicated during fluctuations in diet and weight, changes in concomitant medications, during intercurrent illness, or with any indication of minor bleeding 1
• For elderly patients (>75 years), who may exhibit greater than expected PT/INR response to warfarin, closer monitoring may be necessary 4

Conclusion

Maintaining warfarin therapy during biventricular ICD implantation with careful INR monitoring is the recommended approach to minimize pocket hematoma risk. The target INR should be maintained at <3.0 for the procedure, with regular monitoring post-procedure to ensure therapeutic levels are maintained.