How to restart warfarin in a patient with a metallic mitral valve after clexane bridging?

Restarting Warfarin After Clexane Bridging in Metallic Mitral Valve

Resume warfarin at the patient's previous maintenance dose within 24 hours after adequate hemostasis is achieved, and continue therapeutic-dose clexane (enoxaparin/LMWH) until INR reaches 2.5-3.5 on two consecutive measurements. 1

Timing of Warfarin Resumption

• Start warfarin within 24 hours after the procedure or once hemostasis is secured 1
• For patients with metallic mitral valves (high thrombotic risk), early warfarin resumption is critical to minimize the period of subtherapeutic anticoagulation 1
• Do not delay warfarin restart beyond 24 hours in stable patients without active bleeding 1

Warfarin Dosing Strategy

Use the patient's known maintenance dose—do not use loading doses initially: 1, 2

• Resume at the exact maintenance dose that previously achieved therapeutic INR (target 2.5-3.5 for metallic mitral valve) 1, 2
• Loading doses (1.5x maintenance) may shorten time to therapeutic INR by only 1.2 days but are not routinely recommended 3
• The FDA label and ACC/AHA guidelines recommend restarting at the previous therapeutic dose rather than loading 1, 2

Important Caveat:

Monitor INR more frequently during the perioperative period, as concomitant medications (antibiotics, NSAIDs, acetaminophen), altered nutrition, and changes in drug clearance can affect warfarin response 1

Bridging Anticoagulation Management

Continue therapeutic-dose LMWH (clexane) until adequate oral anticoagulation is re-established: 1

Timing of LMWH Resumption:

• Wait ≥24 hours after surgery before restarting therapeutic-dose LMWH to reduce bleeding risk 4
• For high bleeding-risk procedures, consider waiting 48-72 hours before resuming full-dose LMWH 1
• When resuming LMWH, avoid bolus dosing and consider starting with lower-intensity dosing initially 4

LMWH Continuation:

• Continue therapeutic-dose LMWH until INR is ≥2.5 on two separate measurements at least 24 hours apart 1
• For metallic mitral valves, the target INR is 2.5-3.5 1, 2
• Do not stop LMWH prematurely—patients with mechanical mitral valves have the highest thrombotic risk and require continuous anticoagulation coverage 1

Monitoring Protocol

Check INR frequently during the transition period:

• Measure INR on day 4 after restarting warfarin 1
• Repeat INR testing on days 7-10 1
• Once INR reaches 2.5-3.5 on one measurement, recheck within 24 hours to confirm stability before discontinuing LMWH 1
• Continue weekly INR monitoring initially, then adjust frequency based on stability 2

Special Considerations for Metallic Mitral Valves

Metallic mitral valves carry the highest thrombotic risk among prosthetic valves: 1

• Annual thromboembolism risk without anticoagulation exceeds 10% 1
• These patients require bridging therapy—do not manage like lower-risk patients with bileaflet aortic valves 1
• The target INR of 2.5-3.5 is higher than for aortic mechanical valves (2.0-3.0) due to increased thrombotic risk 1, 2

Avoid These Pitfalls:

• Do not stop LMWH when INR first reaches 2.0—wait for INR ≥2.5 confirmed on repeat testing 1
• Do not use prophylactic-dose LMWH—metallic mitral valves require therapeutic dosing 1
• Do not give high-dose vitamin K to reverse warfarin, as this creates a hypercoagulable state and makes re-anticoagulation difficult 1

Algorithm Summary

1. Day 0-1 post-procedure: Resume warfarin at maintenance dose once hemostasis achieved 1
2. Day 1-2 post-procedure: Resume therapeutic-dose LMWH ≥24 hours after surgery 4
3. Day 4: Check INR 1
4. Continue LMWH at therapeutic dose until INR 2.5-3.5 on two measurements ≥24 hours apart 1
5. Discontinue LMWH only after confirmed therapeutic INR 1
6. Monitor INR closely during first 2 weeks, adjusting warfarin dose as needed 1, 2