What is the protocol for bridging anticoagulation with Lovenox (enoxaparin)?

Perioperative Bridging Protocol with Enoxaparin (Lovenox)

The standard protocol for bridging anticoagulation with enoxaparin involves stopping warfarin 5 days before the procedure, initiating therapeutic-dose enoxaparin when INR falls below 2.0 (typically 3 days before procedure), administering the last pre-procedure dose 24 hours before surgery at half the total daily dose, and resuming anticoagulation based on bleeding risk. 1

Patient Selection for Bridging

Bridging anticoagulation should be reserved for patients at high thromboembolic risk:

• Mechanical heart valves (especially older-generation or mitral position)
• Recent venous thromboembolism (<3 months)
• Atrial fibrillation with CHADS₂ score ≥5
• Recent stroke or TIA (<3 months)
• Active cancer with thrombosis
• Thrombophilia syndromes 1

Pre-Procedure Protocol

1. Stop warfarin: Discontinue 5 days before procedure 2, 1
2. Check baseline labs: Hemoglobin, platelet count, creatinine, INR (7-10 days before procedure) 2
3. Stop antiplatelet drugs: If applicable, 7 days before procedure 2
4. Initiate enoxaparin: When INR falls below 2.0 (typically 3 days before procedure) 1
5. Dosing options:
   • Therapeutic dose: 1 mg/kg subcutaneously twice daily or 1.5 mg/kg once daily 2, 1
   • Intermediate dose: 0.5 mg/kg twice daily or 40 mg twice daily (less studied but showing favorable safety profiles) 2, 3
   • Adjust for renal impairment (CrCl <30 mL/min): Reduce to 1 mg/kg once daily 1
6. Last pre-procedure dose: Administer 24 hours before surgery at half the total daily dose 2, 1
7. Pre-procedure INR check: Proceed with surgery if INR ≤1.5; if INR >1.5 and ≤1.8, consider low-dose oral vitamin K (1-2.5 mg) 2

Post-Procedure Protocol

Based on bleeding risk assessment:

Low Bleeding Risk Procedures

• Resume warfarin: Evening of procedure or next morning 2, 1
• Resume enoxaparin: At previous dose within 24 hours after procedure 2, 1
• Monitor INR: Check on day 4 and discontinue enoxaparin when INR >1.9 2
• Follow-up INR: Recheck at 7-10 days 2

High Bleeding Risk Procedures

• Resume warfarin: Evening of procedure or next morning 2
• Delay enoxaparin: Wait 48-72 hours post-procedure before restarting 2, 1
• Monitor INR: Check on day 4 and discontinue enoxaparin when INR >1.9 2
• Follow-up INR: Recheck at 7-10 days 2

Special Considerations

• Major surgery: Higher risk of bleeding (up to 20%) with therapeutic-dose enoxaparin; consider delaying resumption or using prophylactic doses 4
• Cardiac surgery patients: Both full-dose and half-dose regimens appear safe, with slightly more bleeding events in full-dose regimens and more thromboembolic events in half-dose regimens 5
• Very low bleeding risk procedures: Consider continuing warfarin without interruption (e.g., cataract surgery, dental extractions) 1
• DOACs: Bridging with enoxaparin is generally not required due to their short half-lives 1

Common Pitfalls and Caveats

• Administering the last pre-procedure dose too close to surgery can result in elevated anti-factor Xa levels during surgery, increasing bleeding risk 1
• Resuming therapeutic anticoagulation too early after high bleeding risk procedures can lead to major bleeding (rates as high as 20%) 1
• Failing to adjust dosing for renal impairment can lead to drug accumulation and increased bleeding risk 1
• Not considering procedure-specific bleeding risk when determining resumption timing can lead to preventable bleeding complications 1

The evidence supports that bridging therapy with enoxaparin is feasible and associated with a low incidence of major bleeding and thromboembolic complications when appropriate protocols are followed 6.