What is the protocol for bridging from Coumadin (warfarin) to Lovenox (enoxaparin) for a surgical procedure?

Warfarin to Lovenox Bridging Protocol for Surgical Procedures

For patients requiring temporary interruption of warfarin anticoagulation for surgery, a structured bridging protocol using therapeutic-dose enoxaparin (Lovenox) should be implemented, with timing based on thromboembolism risk and procedure bleeding risk. 1, 2

Risk Assessment

Thromboembolism Risk

• High risk: Mechanical heart valves, recent VTE (<3 months), antiphospholipid syndrome with recurrent thrombosis 2
• Moderate risk: Atrial fibrillation with CHA₂DS₂-VASc score 4-6, recurrent VTE 2
• Low risk: Atrial fibrillation with CHA₂DS₂-VASc score <4, single VTE >3 months ago 2

Bleeding Risk

• High bleeding risk: Major surgery, spinal/intracranial procedures, extensive debridement 2
• Low bleeding risk: Minor procedures, superficial procedures 2

Standard Bridging Protocol

Pre-Procedure Phase

1. 7-10 days before procedure:

   • Assess thromboembolism and bleeding risk
   • Check baseline labs (hemoglobin, platelet count, creatinine, INR) 1

2. 5-6 days before procedure:

   • Stop warfarin 1

3. 3 days before procedure:

   • Start therapeutic-dose LMWH (enoxaparin) 1
   • Dosing options:
     • Enoxaparin 1.5 mg/kg once daily or 1.0 mg/kg twice daily 1, 2
     • Dalteparin 200 IU/kg once daily or 100 IU/kg twice daily 1, 2
     • Tinzaparin 175 IU/kg once daily 1, 2

4. 1 day before procedure:

   • Administer last pre-procedure dose of LMWH at least 24 hours before surgery
   • Use half the total daily dose for once-daily regimens 1
   • Check INR before procedure (target ≤1.5) 1
   • If INR >1.5 but ≤1.8, consider low-dose oral vitamin K (1-2.5 mg) 1

Post-Procedure Phase

1. Day of procedure or day after:

   • Resume warfarin at maintenance dose 1, 2

2. Post-procedure LMWH resumption:

   • Low bleeding risk procedures:
     • Resume therapeutic-dose LMWH 24 hours post-procedure 1, 2
   • High bleeding risk procedures:
     • Wait 48-72 hours before resuming therapeutic-dose LMWH 1, 2
     • Consider starting with prophylactic-dose LMWH (enoxaparin 40 mg daily) 12-24 hours post-procedure if hemostasis is adequate 1, 2

3. Monitoring:

   • Check INR on day 4 post-procedure 1
   • Discontinue LMWH when INR >1.9 1, 2
   • Recheck INR 7-10 days post-procedure 1

Special Considerations

Mechanical Heart Valves

• Patients with mechanical heart valves require therapeutic-dose bridging due to high thromboembolism risk 1, 2
• The FDA has strengthened warnings that Lovenox is not recommended for thromboprophylaxis in patients with prosthetic heart valves 1
• Consider unfractionated heparin for patients with severe renal insufficiency 2

Minor Procedures

• For minor dental, skin, or eye procedures, consider continuing warfarin without interruption if bleeding risk is minimal 1

Potential Complications

• Bridging therapy is associated with increased risk of bleeding compared to warfarin interruption without bridging 3
• Wounds of patients given anticoagulation bridges may take longer to heal than those given warfarin only 4
• Carefully assess the need for bridging, as it may be unnecessary for patients at low risk of thromboembolism 3

Practical Implementation Tips

• Use intermittent pneumatic compression devices in high bleeding risk patients when LMWH is delayed 2
• Individualize the timing of post-procedure anticoagulation based on hemostasis assessment 2
• For urgent procedures, consider consulting hematology/cardiology services 1
• Outpatient bridging therapy is feasible for most patients, avoiding unnecessary hospitalization 5