Do you have to bridge warfarin (Coumadin) in outpatients?

Bridging Warfarin in Outpatients

Routine bridging anticoagulation is NOT recommended for most outpatients on warfarin who require temporary interruption of therapy for procedures. 1

Risk Stratification for Bridging Decisions

High Thrombotic Risk (Bridging Recommended)

• Mechanical mitral valve 1
• Prosthetic valve with atrial fibrillation 1
• Recent venous thromboembolism (<3 months) 1, 2
• Severe thrombophilia (protein C or protein S deficiency, antiphospholipid syndrome) 1, 2
• Non-valvular atrial fibrillation with CHADS-VASc score >5 1

Low to Moderate Thrombotic Risk (Bridging NOT Recommended)

• Non-valvular atrial fibrillation with CHADS-VASc score ≤5 1
• Venous thromboembolism >3 months ago 1
• Most thrombophilias (including Factor V Leiden and prothrombin mutations) 1
• Stable coronary artery disease 1

Evidence Supporting No Bridging for Most Patients

The BRIDGE trial demonstrated that for patients with atrial fibrillation (without moderate-severe mitral stenosis or mechanical heart valves), no bridging was non-inferior to bridging with LMWH for prevention of arterial thromboembolism and significantly decreased bleeding risk 1. This high-quality evidence has shifted practice away from routine bridging.

Multiple guidelines now recommend against routine bridging for most patients, as it increases bleeding risk without reducing thromboembolic events 1, 2. Studies show higher rates of major hemorrhage with bridging (2.7% vs 0.5%) with no reduction in thromboembolism 2.

Standard Protocol for Warfarin Interruption

For patients NOT requiring bridging:

1. Stop warfarin 5 days before procedure 1
2. Check INR before procedure to ensure it's <1.5 1
3. Resume warfarin on the evening of or day after procedure at usual dose 1
4. No LMWH needed 1

For patients requiring bridging (high thrombotic risk):

1. Stop warfarin 5 days before procedure 1
2. Start LMWH (e.g., dalteparin 100 IU/kg twice daily) 2-3 days after stopping warfarin 3
3. Administer last dose of LMWH at least 24 hours before procedure 1
4. Resume warfarin evening of procedure at usual dose 3
5. Resume LMWH 24 hours after procedure for low bleeding risk procedures 1
6. For high bleeding risk procedures, delay LMWH for 48-72 hours 1
7. Continue LMWH until INR reaches therapeutic range (≥2.0) 1, 2

Common Pitfalls to Avoid

1. Unnecessary bridging in low-risk patients - increases bleeding risk without benefit 2
2. Failure to bridge truly high-risk patients - increases thrombotic risk in patients with mechanical valves or recent VTE 2
3. Restarting LMWH too soon after high bleeding risk procedures - significantly increases bleeding risk 2
4. Continuing bridging too long - continuing LMWH after warfarin is therapeutic (INR ≥2.0) increases bleeding risk 2

Special Considerations

Even when warfarin is temporarily discontinued, patients still have an increased risk of post-procedure bleeding compared to non-anticoagulated patients 1. Consider deferring elective high-risk procedures beyond 3 months of anticoagulation if safe to do so, especially for patients with recent VTE 2.

For patients undergoing minor procedures with low bleeding risk (dental, skin, cataract procedures), consider continuing warfarin without interruption 1.