When to Stop Enoxaparin During Warfarin Bridging for LV Clot
Stop enoxaparin when the INR reaches ≥2.0 on two consecutive measurements, typically after 4-5 days of overlapping therapy with warfarin. 1
Initiation and Overlap Protocol
Start warfarin and enoxaparin concomitantly when initiating anticoagulation for LV clot, as warfarin's anticoagulant effect is delayed and requires several days to achieve therapeutic levels. 1
Continue full therapeutic-dose enoxaparin (1 mg/kg subcutaneously every 12 hours or 1.5 mg/kg once daily) throughout the overlap period to ensure continuous anticoagulation. 1, 2
Overlap therapy should continue for 4-5 days minimum to allow warfarin to produce adequate anticoagulation through depletion of vitamin K-dependent clotting factors. 1
INR Monitoring and Enoxaparin Discontinuation
Check INR daily after initiating warfarin until stable therapeutic levels are achieved. 1
Discontinue enoxaparin only when INR reaches ≥2.0 for two consecutive days, ensuring that the therapeutic effect is sustained and not a transient elevation. 3, 4
For patients with LV clot, the target INR range is 2.0-3.0, which is the standard intensity for venous thromboembolism and most arterial thrombi. 3
Critical Timing Considerations
The FDA label explicitly states that "warfarin therapy be overlapped with heparin for 4 to 5 days, until warfarin sodium tablets have produced the desired therapeutic response as determined by PT/INR. When warfarin sodium tablets have produced the desired PT/INR or prothrombin activity, heparin may be discontinued." 1 This applies equally to enoxaparin as a heparin alternative.
Do not stop enoxaparin prematurely even if a single INR measurement shows ≥2.0, as this may represent early warfarin effect that has not yet stabilized. 1
The minimum 4-5 day overlap is mandatory regardless of how quickly the INR rises, because warfarin's full anticoagulant effect requires depletion of all vitamin K-dependent factors, particularly Factor II (prothrombin), which has a half-life of 60-72 hours. 3
Special Considerations for LV Clot
LV clot represents a high thromboembolic risk condition, particularly in the setting of anterior MI with reduced ejection fraction (≤40%), making adequate anticoagulation during the transition period critical. 2
Research comparing enoxaparin to warfarin for LV thrombus prevention found that 30 days of enoxaparin followed by discontinuation resulted in numerically higher (though not statistically significant) rates of thrombus at 3.5 months compared to 3 months of warfarin, suggesting that premature discontinuation of anticoagulation may allow thrombus formation. 2
Common Pitfalls to Avoid
Never discontinue enoxaparin based on a single INR measurement, even if therapeutic, as this does not guarantee sustained anticoagulation. 1
Avoid stopping enoxaparin before the 4-5 day minimum overlap period unless there is major bleeding, as early discontinuation leaves patients vulnerable to thromboembolism during the period when warfarin has not yet achieved full anticoagulant effect. 1
Do not draw INR levels for warfarin monitoring within 5 hours of IV heparin bolus, 4 hours of stopping continuous IV heparin, or 24 hours of subcutaneous heparin/enoxaparin, as these agents can artificially elevate the INR and lead to premature discontinuation of bridging therapy. 1