Warfarin Resumption After 5-Day Interruption in Valve Replacement Patient
Resume warfarin immediately at the usual maintenance dose of 5mg tonight, and restart bridging anticoagulation with therapeutic-dose heparin (either IV unfractionated heparin or subcutaneous LMWH) until the INR returns to therapeutic range (2.5-3.5 for mechanical valves). 1
Immediate Management Algorithm
Step 1: Check Current INR
- Obtain stat INR to assess current anticoagulation status 1
- After 5 days off warfarin, the INR is almost certainly subtherapeutic (<1.5) given warfarin's 42-hour half-life 1
- The patient is currently at high risk for valve thrombosis during this unprotected period 1
Step 2: Restart Warfarin Tonight
- Give the usual maintenance dose of 5mg orally tonight—do not use a loading dose 2, 3
- Loading doses increase hemorrhagic complications without providing faster protection against thrombosis 2
- The anticoagulant effect will not be therapeutic for 48-72 hours due to the time required to deplete vitamin K-dependent clotting factors 1
Step 3: Initiate Bridging Anticoagulation Immediately
For mechanical valve patients (which this patient has), bridging is mandatory—this is a Class I recommendation: 1
Option A: IV Unfractionated Heparin (UFH)
- Start continuous IV infusion immediately 1
- Adjust to maintain aPTT at 1.5-2.5 times control (or anti-Xa 0.3-0.6 IU/mL) 1
- Continue until INR is therapeutic (≥2.0) for at least 24 hours 1
Option B: Subcutaneous LMWH
- Give therapeutic dose subcutaneous LMWH twice daily 1
- Dose: 1 mg/kg enoxaparin every 12 hours (or equivalent LMWH) 1
- Monitor anti-Xa levels 4-6 hours after dose, targeting 0.8-1.2 U/mL 1
- Continue until INR is therapeutic (≥2.0) for at least 24 hours 1
Critical Risk Assessment
Why This Patient Requires Bridging
All mechanical valve patients who have been off anticoagulation for 5 days are at high thrombotic risk and require bridging: 1
- Mechanical valves (especially mitral position) carry the highest thrombotic risk 1
- Five days without anticoagulation represents significant unprotected time 1
- The risk of valve thrombosis without bridging far exceeds bleeding risk from heparin 1
The only exception where bridging might be omitted is a bileaflet mechanical aortic valve with NO other risk factors (no atrial fibrillation, no prior thromboembolism, no LV dysfunction, no hypercoagulable state) 1. However, even in this low-risk scenario, 5 days is pushing the safety limit, and bridging should be strongly considered 1.
INR Monitoring Schedule
- Check INR daily until therapeutic range is achieved 2, 3
- Once therapeutic (INR 2.5-3.5 for mechanical valves), check 2-3 times weekly for 2 weeks 2
- Then weekly for 1 month, then every 2-4 weeks if stable 2
- Target INR depends on valve type: 1, 2
- Bileaflet aortic valve: INR 2.0-3.0
- Tilting disk or bileaflet mitral valve: INR 2.5-3.5
- Caged ball/disk valve: INR 2.5-3.5 plus aspirin 75-100mg daily
Common Pitfalls to Avoid
Do NOT give high-dose vitamin K to "speed up" warfarin effect—this creates a hypercoagulable state and makes subsequent anticoagulation difficult 1
Do NOT restart warfarin without bridging anticoagulation in a mechanical valve patient—the 48-72 hour gap before therapeutic INR is achieved leaves the patient vulnerable to catastrophic valve thrombosis 1
Do NOT use a loading dose of warfarin (>5mg)—this increases bleeding risk without faster protection 2, 3
Do NOT stop bridging anticoagulation until INR has been therapeutic for at least 24 consecutive hours 1
Special Considerations
If this interruption was planned (e.g., for a procedure), the management was suboptimal. For future procedures, warfarin should be stopped only 2-4 days before (not 5 days), and bridging should have been started when INR fell below 2.0 1. The current 5-day gap without bridging represents a dangerous lapse in anticoagulation management for a mechanical valve patient 1.