When to initiate Lovenox (enoxaparin) prior to a procedure with a 4-day warfarin hold for a patient with a goal INR of 2.5-3.5?

Initiating Lovenox for a Patient with Goal INR 2.5-3.5 Requiring a 4-Day Warfarin Hold

For a patient with a goal INR of 2.5-3.5 requiring a 4-day warfarin hold before a procedure, therapeutic-dose Lovenox (enoxaparin) should be initiated when the INR falls below 2.0, typically 48 hours after stopping warfarin.

Bridging Protocol Based on Thrombotic Risk

The approach to bridging anticoagulation depends on the patient's thrombotic risk:

High Thrombotic Risk Patients (Goal INR 2.5-3.5)

Patients with a goal INR of 2.5-3.5 are typically considered high-risk for thromboembolism, which includes:

• Mechanical heart valves (especially mitral position)
• Recent thromboembolism
• Atrial fibrillation with previous stroke/TIA or multiple risk factors

For these high-risk patients:

1. Stop warfarin 4 days before the procedure
2. Begin therapeutic-dose Lovenox when INR falls below 2.0 (typically 48 hours after stopping warfarin) 1
3. Use weight-based dosing: 1 mg/kg subcutaneously every 12 hours or 1.5 mg/kg once daily
4. Administer the last dose of Lovenox 24 hours before the procedure 1
5. Resume Lovenox 24-48 hours after the procedure once hemostasis is achieved 1
6. Restart warfarin within 24 hours after the procedure if hemostasis is adequate 1
7. Continue Lovenox until the INR returns to the therapeutic range (2.5-3.5)

Dosing Considerations

• For patients with normal renal function, use full therapeutic dosing: 1 mg/kg every 12 hours
• Adjust dose for renal impairment:
  • CrCl 30-50 mL/min: Consider 1 mg/kg once daily
  • CrCl <30 mL/min: Use caution or consider unfractionated heparin instead

Timing of Perioperative Anticoagulation

Time	Action
Day -4	Stop warfarin
Day -2 (or when INR <2.0)	Start Lovenox
Day -1	Last Lovenox dose (24h before procedure)
Day 0	Procedure
Day +1	Resume Lovenox if hemostasis adequate (24h post-procedure)
	Resume warfarin
Days +1 to +X	Continue Lovenox until INR reaches 2.5-3.5

Important Considerations

• The higher target INR range (2.5-3.5) suggests this patient likely has a mechanical heart valve or other high-risk condition, warranting aggressive bridging 1
• For patients with mechanical heart valves, therapeutic anticoagulation is critical to prevent valve thrombosis and systemic embolization 1
• Avoid using high-dose vitamin K to reverse warfarin, as this may create a hypercoagulable state 1
• If the procedure is ultra-high bleeding risk, consider consulting the proceduralist about the timing of postoperative anticoagulation resumption

Potential Pitfalls

1. Delayed INR recovery: After restarting warfarin, it may take 5-10 days to reach therapeutic range, necessitating continued Lovenox
2. Bleeding risk: Resuming full-dose anticoagulation too soon after a procedure increases bleeding risk
3. Inadequate bridging: Starting Lovenox too late or stopping too early increases thrombotic risk
4. Renal function: Failure to adjust Lovenox dosing for impaired renal function can lead to accumulation and bleeding

By following this protocol, you can minimize both thrombotic and bleeding risks during the perioperative period for this high-risk patient requiring temporary interruption of warfarin therapy.