When should warfarin (Coumadin) be held and bridged with Lovenox (enoxaparin)?

When to Hold Warfarin and Bridge with Lovenox: Evidence-Based Recommendations

Bridging therapy with low-molecular-weight heparin (LMWH) such as Lovenox should only be used for patients with mechanical heart valves who require interruption of warfarin therapy, as the BRIDGE trial demonstrated that most other patients do not benefit from bridging and experience increased bleeding risk. 1

Risk Stratification for Bridging Decisions

High Thromboembolism Risk (Bridging Recommended)

• Patients with mechanical heart valves 1
• FDA specifically warns against using Lovenox for thromboprophylaxis in patients with prosthetic heart valves 1

Low/Moderate Thromboembolism Risk (No Bridging Recommended)

• Patients with atrial fibrillation without mechanical heart valves 1
• The 2019 AHA/ACC/HRS guidelines specifically state that absence of bridging was found to be noninferior to bridging with LMWH for prevention of arterial thromboembolism and decreased bleeding risk 1

Evidence Against Routine Bridging

The BRIDGE trial (Bridging Anticoagulation in Patients who Require Temporary Interruption of Warfarin Therapy for an Elective Invasive Procedure or Surgery) was a landmark randomized, double-blind, placebo-controlled trial of 1,884 patients with atrial fibrillation requiring perioperative interruption of warfarin therapy. This trial demonstrated that:

• No bridging was noninferior to bridging with LMWH for prevention of arterial thromboembolism
• No bridging significantly decreased the risk of bleeding
• This evidence led to a change in guidelines, with the level of evidence upgraded from C to B-R 1

Protocol for Warfarin Management Without Bridging

For patients who do NOT require bridging (most atrial fibrillation patients):

1. Stop warfarin 5 days before procedure 1
2. Confirm INR <1.5 before procedure 1
3. Resume warfarin on the evening of or day after procedure at usual maintenance dose 1
4. Check INR 4-5 days after resuming warfarin 1

Protocol for Warfarin Management With Bridging (Mechanical Heart Valves)

For patients who DO require bridging:

1. Stop warfarin 5 days before procedure 1
2. Start therapeutic-dose LMWH (enoxaparin 1.5 mg/kg daily or 1 mg/kg twice daily) 3 days before procedure 1
3. Administer last dose of LMWH at least 24 hours before procedure 1
4. Resume warfarin at usual dose on evening of or day after procedure 1
5. Restart LMWH 24-72 hours after procedure based on bleeding risk:
   • Low bleeding risk: Resume LMWH 24 hours post-procedure
   • High bleeding risk: Wait 48-72 hours before resuming LMWH 1
6. Continue LMWH until INR reaches therapeutic range 1

Common Pitfalls to Avoid

• Unnecessary bridging in low-risk patients increases bleeding risk without reducing thromboembolism 1
• Restarting LMWH too soon after major surgery (within 24 hours) significantly increases bleeding risk 1
• Using LMWH for bridging in patients with prosthetic heart valves (FDA warning against this practice) 1
• Failure to adjust bridging protocols based on procedural bleeding risk 1
• Resuming full-dose anticoagulation too soon after procedures with high bleeding risk 1

Special Considerations

For patients undergoing minor procedures with low bleeding risk (such as dental, dermatologic, or ophthalmologic procedures), consider:

• Continuing warfarin without interruption for certain procedures 1
• Reducing warfarin dose 4-5 days before procedure to allow INR to fall to 1.3-1.5 1

Remember that the evidence strongly supports avoiding bridging therapy for most patients with atrial fibrillation, as it increases bleeding risk without providing additional protection against thromboembolism.