Warfarin Bridging Protocol for Surgery

Risk Assessment for Bridging

Patients with recent VTE within 3 months, active cancer with VTE, mechanical heart valves, atrial fibrillation with high CHADS2 score, or antiphospholipid syndrome with recurrent thrombosis are considered high thromboembolic risk and may require bridging anticoagulation 1, 2, 3, 4
Patients with atrial fibrillation and low CHADS2 score, VTE more than 3 months ago, or no other major risk factors are considered low thromboembolic risk and do not require bridging anticoagulation 2

Warfarin should be stopped 5 days before surgery, and bridging anticoagulation with LMWH should be considered for high-risk patients only 1, 2, 3
The American College of Chest Physicians recommends checking INR the day before surgery and proceeding if INR ≤1.5 4, 3
For patients with INR >1.5 and ≤1.8, low-dose oral vitamin K (1-2.5 mg) may be considered 4, 3
LMWH should be started when INR falls below 2.0, typically 3 days before surgery, at a therapeutic dose (e.g., enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily) 1, 4, 3
The last pre-operative LMWH dose should be administered 24 hours before surgery at half the total daily dose 4, 3

Warfarin should be resumed 12-24 hours after surgery, and LMWH should be continued until INR reaches therapeutic range (≥2.0) 1, 2, 4, 3
For high bleeding risk procedures, therapeutic LMWH should be delayed for 48-72 hours, and prophylactic LMWH may be considered 12 hours after surgery 1, 4

For minor dental procedures, warfarin may be continued with oral prohemostatic agents, and for minor dermatologic procedures and cataract surgery, continuing warfarin is often appropriate 2

Major bleeding risk increases with therapeutic-dose LMWH, particularly when resumed too soon after high bleeding risk procedures 4
Delaying elective procedures until at least 3 months after acute VTE may reduce the risk of thromboembolism 1

Most recommendations are based on observational studies rather than randomized trials, with a strength of evidence that is generally considered low to moderate 2