For an adult with atrial fibrillation on chronic warfarin undergoing an elective surgery, should the warfarin be stopped abruptly or discontinued several days beforehand, and is bridging with low‑molecular‑weight heparin necessary?

Warfarin Management for Atrial Fibrillation Before Surgery

For most patients with atrial fibrillation on warfarin undergoing elective surgery, warfarin should be stopped 5 days before the procedure without bridging anticoagulation, as bridging increases bleeding risk without reducing stroke risk in this population. 1

Discontinuation Protocol (No Bridging Required)

Warfarin must be discontinued gradually, not abruptly, following this timeline:

• Stop warfarin 5 days (five doses) before surgery to allow the INR to fall to ≤1.5 1, 2
• Check INR the day before surgery; if INR is between 1.5-1.8, consider low-dose oral vitamin K (1-2.5 mg) for reversal 1, 3
• Proceed with surgery only if INR ≤1.5 1, 2
• Resume warfarin on the evening of surgery or the next morning at the usual maintenance dose once adequate hemostasis is achieved 1

When Bridging IS Required (High Thrombotic Risk Only)

Bridging with low-molecular-weight heparin is indicated only for patients at very high thrombotic risk, specifically: 1

• Mechanical prosthetic heart valve (especially mitral position) 1
• Venous thromboembolism within the last 3 months 1
• Atrial fibrillation with mitral stenosis 3
• Prior stroke/TIA with CHADS₂ score ≥5 3

Bridging Protocol (When Required)

• Stop warfarin 5-6 days before surgery 1
• Start therapeutic-dose LMWH 36 hours after the last warfarin dose (approximately 3 days before surgery) 1
• Give the last LMWH dose 24 hours before surgery at half the normal daily dose 1
• For high-bleeding-risk procedures, delay resuming LMWH for 48-72 hours post-operatively; for low-bleeding-risk procedures, resume within 24 hours 1, 3
• Continue LMWH until INR returns to therapeutic range 3

Why Bridging Is NOT Recommended for Most AF Patients

The 2016 AAGBI guidelines explicitly state that routine bridging anticoagulation with LMWH before surgery is not recommended for patients with atrial fibrillation on warfarin. 1 This recommendation is based on evidence showing:

• Bridging increases major bleeding risk up to 20% when treatment-dose LMWH is given postoperatively without regard for surgical bleeding risk 1
• The BRUISE CONTROL trial demonstrated that bridging increased pocket hematomas from 3.5% to 16% in cardiac device procedures 1
• Stroke risk during the brief perioperative period is extremely low (approximately 0.1%) even without bridging 1

Critical Pitfalls to Avoid

• Never assume 5 days is sufficient without verification: Approximately 7% of patients still have INR >1.5 after 5 days of warfarin discontinuation 3
• Elderly patients and those with high-intensity INR ranges (3.0-4.0) may require longer interruption periods beyond 5 days 1, 2
• Do not give routine vitamin K for INR 1.5-1.9 measured 1-2 days before surgery, as it causes postoperative warfarin resistance without proven benefit 3
• Resuming full-dose LMWH too early post-procedure causes major bleeding in up to 20% of patients 3

Procedure-Specific Considerations

Low-Risk Procedures (Continue Warfarin)

For cataract surgery, dental extractions, and diagnostic endoscopy, warfarin can be continued without interruption if INR is within therapeutic range 1, 3

High-Risk Procedures (Always Stop Warfarin)

For major abdominal surgery, orthopedic surgery, neurosurgery, or procedures with neuraxial anesthesia, warfarin must be stopped 5 days before with INR verification 2, 3