What anticoagulant regimen to prescribe on discharge for a patient with Deep Vein Thrombosis (DVT) currently on Low Molecular Weight Heparin (LMWH) with Warfarin?

Discharge Anticoagulation for DVT Patients on LMWH with Warfarin

Continue both LMWH and warfarin together until the INR is ≥2.0 for at least 24 hours (minimum 5 days of overlap), then discharge on warfarin monotherapy with a target INR of 2.0-3.0. 1

Transition Protocol from LMWH to Warfarin

Overlap Requirements

• Warfarin should be started early (same day as LMWH initiation) and overlapped with LMWH for a minimum of 5 days AND until INR ≥2.0 for at least 24 hours 1
• Do not discontinue LMWH until both conditions are met: the 5-day minimum duration AND therapeutic INR on two consecutive measurements at least 24 hours apart 1, 2
• This overlap is critical because warfarin initially creates a prothrombotic state before achieving anticoagulation 2

Warfarin Dosing Strategy

• Start warfarin at 5 mg daily (not a loading dose) and adjust based on INR response 3, 2
• Target INR range: 2.0-3.0 (target 2.5) for all treatment durations 1
• Measure INR at least twice weekly during the transition period, then weekly once stable on warfarin monotherapy 1

Alternative: Direct Oral Anticoagulants (DOACs) - Preferred Option

For most patients with acute DVT, DOACs (apixaban, rivaroxaban, edoxaban, or dabigatran) are now preferred over warfarin due to superior safety and efficacy profiles. 1

DOAC Advantages Over Warfarin

• Strong recommendation from 2024 Chest Guidelines: DOACs are preferred over VKA (warfarin) for treatment phase anticoagulation 1
• No INR monitoring required 1
• More predictable anticoagulation effect 1
• Lower major bleeding rates in pooled analyses 1

Specific DOAC Regimens for DVT

Rivaroxaban (preferred for simplicity):

• 15 mg orally twice daily with food for 21 days, then 20 mg once daily with food 1, 4
• No LMWH bridging required - can start immediately 1

Apixaban:

• 10 mg orally twice daily for 7 days, then 5 mg twice daily 1, 5
• No LMWH bridging required 5

Edoxaban or Dabigatran:

• Require LMWH lead-in for at least 5 days before starting the DOAC 1
• Edoxaban: 60 mg once daily (30 mg if CrCl 30-50 mL/min or weight ≤60 kg) 1

Duration of Anticoagulation After Discharge

Provoked DVT (Surgery/Trauma)

• 3 months of anticoagulation for DVT related to major reversible risk factors 1
• Can safely stop after 3 months in most cases 1

Unprovoked DVT

• Minimum 3 months, but extended-phase anticoagulation (no scheduled stop date) is recommended 1
• Strong recommendation for indefinite anticoagulation with a DOAC in unprovoked VTE 1

Cancer-Associated DVT

• Oral factor Xa inhibitor (apixaban, edoxaban, or rivaroxaban) is preferred over LMWH 1
• Extended anticoagulation with no scheduled stop date is recommended 1
• If LMWH is used: dalteparin 200 IU/kg daily for 1 month, then 150 IU/kg daily for at least 3-6 months 1

Special Populations

Renal Impairment (CrCl <30 mL/min)

• Warfarin is preferred as it is hepatically metabolized 1
• Avoid DOACs in severe renal impairment (CrCl <25-30 mL/min) 5
• UFH is an alternative if warfarin is contraindicated 1

Pregnancy

• Continue LMWH throughout pregnancy - warfarin is teratogenic and absolutely contraindicated 1, 3
• LMWH is safe for nursing mothers 3

Heparin-Induced Thrombocytopenia (HIT)

• Use direct thrombin inhibitors (argatroban, lepirudin) or fondaparinux 1
• Do not start warfarin until platelet count recovers, then overlap with DTI for at least 5 days until INR ≥2.0 1

Common Pitfalls to Avoid

Critical Errors in Warfarin Transition

• Never discontinue LMWH before 5 days of overlap, even if INR is therapeutic earlier 1, 2
• Stopping LMWH too early (before adequate warfarin effect) significantly increases recurrent VTE risk 2, 6
• Initial warfarin dosing creates a transient hypercoagulable state due to rapid protein C depletion 2

Monitoring Failures

• Inadequate INR monitoring after discharge leads to 30% of patients being underdosed and 8% overdosed 6
• Ensure clear follow-up plan with primary care or anticoagulation clinic within 3-5 days of discharge 6

Drug Interactions

• NSAIDs significantly increase bleeding risk with warfarin - avoid or use with extreme caution 6
• Multiple medications affect warfarin metabolism - review all medications before discharge 1

Discharge Prescription Summary

If continuing warfarin:

• Warfarin dose (based on current INR response) with target INR 2.0-3.0
• LMWH (enoxaparin 1 mg/kg twice daily) until INR ≥2.0 x 24 hours
• INR check within 3-5 days of discharge
• Duration: minimum 3 months (longer if unprovoked or cancer-associated)

If switching to DOAC (preferred):

• Rivaroxaban 15 mg twice daily with food x 21 days, then 20 mg daily
• OR Apixaban 10 mg twice daily x 7 days, then 5 mg twice daily
• No INR monitoring required
• Duration: minimum 3 months (longer if unprovoked or cancer-associated)