What is the best course of action for a patient with DVT whose warfarin (Coumadin) has been held?

Management of DVT with Subtherapeutic INR

For a patient with DVT whose warfarin has been held and currently has a subtherapeutic INR of 2.9 (previously 3.7), low molecular weight heparin (LMWH) should be initiated while warfarin is restarted to maintain adequate anticoagulation until therapeutic INR is achieved. 1

Immediate Management

• Restart warfarin therapy and overlap with LMWH (such as enoxaparin 1 mg/kg twice daily) until the INR returns to the therapeutic range (2.0-3.0) for at least 24 hours 1
• Monitor INR daily until stable and within therapeutic range 2
• Target INR should be 2.0-3.0 for DVT treatment 1
• Continue LMWH for a minimum of 5 days and until the INR is >2.0 for at least 24 hours 1

Considerations for Warfarin Dosing

• Adjust warfarin dose based on current INR of 2.9 (slightly below therapeutic range) 2
• Since the INR is only slightly below therapeutic range, a modest increase in warfarin dose may be sufficient 2, 3
• Avoid large loading doses as they may lead to excessive anticoagulation 3
• Consider factors that may have contributed to the INR drop, such as:
  • Medication interactions affecting warfarin metabolism 4
  • Dietary changes (increased vitamin K intake) 2
  • Poor medication adherence 4

Duration of Anticoagulation Therapy

Duration of therapy depends on the clinical context of the DVT:

• First episode related to a reversible risk factor (e.g., surgery, trauma): 3 months of anticoagulation 1
• First episode of unprovoked DVT: at least 6 months of anticoagulation 1, 5
• Recurrent DVT or unprovoked DVT: consider indefinite anticoagulation with periodic reassessment of risks and benefits 1, 6
• Cancer-associated DVT: LMWH monotherapy for at least 3-6 months or as long as cancer is active 1

Monitoring and Follow-up

• Once therapeutic INR is achieved, monitor INR regularly (typically every 1-4 weeks depending on stability) 2
• Assess for signs and symptoms of recurrent DVT or bleeding complications at each visit 4
• Consider graduated compression stockings (30-40 mmHg) for 2 years after DVT diagnosis to reduce risk of post-thrombotic syndrome 1
• Educate patient about:
  • Importance of medication adherence 4
  • Dietary consistency regarding vitamin K intake 2
  • Signs and symptoms of bleeding or recurrent thrombosis 4

Common Pitfalls to Avoid

• Failing to bridge with LMWH when INR falls below therapeutic range in a patient with recent DVT 1
• Excessive warfarin dose adjustments leading to INR fluctuations 3
• Discontinuing anticoagulation too early, especially in unprovoked DVT 1, 5
• Not considering patient-specific factors that may affect warfarin metabolism 2
• Inadequate monitoring during dose adjustments 2

By implementing this approach, you can effectively manage a patient with DVT whose warfarin has been held and currently has a subtherapeutic INR, minimizing the risk of recurrent thrombosis while safely returning to therapeutic anticoagulation.