Does stopping acenocoumarol (vitamin K antagonist) require bridging anticoagulation therapy?

Does Stopping Acenocoumarol Require Bridging?

Bridging anticoagulation when stopping acenocoumarol (a vitamin K antagonist) is only recommended for patients at high risk for thromboembolism, not for all patients. 1

Risk Stratification Determines Bridging Need

The decision to bridge depends entirely on the patient's thromboembolic risk category:

High-Risk Patients (Bridging Recommended)

For high-risk patients, bridging with therapeutic-dose low molecular weight heparin (LMWH) or unfractionated heparin is suggested during the interruption period. 1

High-risk conditions include: 1

• Mechanical mitral valve in any position
• Caged ball or tilting-disk mechanical valve (any position)
• Mechanical heart valve with recent stroke or TIA (<3 months)
• Recent venous thromboembolism (<3 months, particularly <1 month)
• Atrial fibrillation with CHA₂DS₂-VASc ≥7 (or 5-6 with recent stroke/TIA)
• Severe thrombophilia (protein C/S/antithrombin deficiency, homozygous factor V Leiden)
• Active cancer with high VTE risk

Low-to-Moderate Risk Patients (No Bridging)

For low-to-moderate risk patients, bridging is not recommended as it increases bleeding risk without reducing thromboembolism. 1

Low-to-moderate risk includes: 1

• Bileaflet mechanical aortic valve without major stroke risk factors
• Atrial fibrillation with CHA₂DS₂-VASc 1-6 (without recent stroke)
• Venous thromboembolism >3 months ago

The 2022 CHEST guidelines explicitly recommend against bridging in these patients based on evidence showing increased bleeding without thromboembolism benefit. 1

Practical Bridging Protocol (When Indicated)

Preoperative Management

Stop acenocoumarol 5 days before surgery to allow INR to fall below therapeutic range. 1, 2

Start therapeutic-dose LMWH or UFH when INR falls below 2.0 (typically 36-48 hours before surgery). 1, 2

Stop bridging anticoagulation:

• 4-6 hours before surgery for intravenous UFH 1
• 12-24 hours before surgery for subcutaneous LMWH 1

Postoperative Management

Resume acenocoumarol 12-24 hours after surgery (evening of surgery or next morning) when adequate hemostasis is achieved. 1, 2

Restart bridging anticoagulation 24 hours postoperatively at therapeutic dose (or low-dose prophylactic heparin in selected cases). 1, 2

Continue both acenocoumarol and bridging therapy until INR is therapeutic (≥2.0) for 2 consecutive days, then discontinue heparin. 1, 3

Special Situations

Low Bleeding Risk Procedures

For dental extractions, cataract surgery, or minor dermatologic procedures, continue acenocoumarol without interruption using local hemostatic measures. 1, 4

If acenocoumarol must be stopped for dental procedures, stop only 2-3 days before (not the full 5 days) and use tranexamic acid mouthwash for hemostasis. 1, 4

Emergency Surgery

Reverse acenocoumarol with 4-factor prothrombin complex concentrate (onset 5-15 minutes) rather than fresh frozen plasma (onset 1-4 hours). 1, 2

Add low-dose vitamin K if needed, but avoid high doses that cause prolonged resistance to re-anticoagulation. 2

Critical Evidence and Pitfalls

The 2024 AHA/ACC guidelines note that meta-analyses show bridging increases bleeding risk 6.0- to 7.7-fold without clear thromboembolism benefit in most patients. 1 The 2022 CHEST systematic review of 6,195 VKA-treated patients found bridging increased bleeding (3.9% vs 0.4%) with no reduction in recurrent VTE (0.7% vs 0.5%). 1

Common pitfall: Bridging all patients on acenocoumarol reflexively without risk stratification leads to unnecessary bleeding complications. 1

Common pitfall: Stopping acenocoumarol for low-bleeding-risk procedures (dental work, cataract surgery) unnecessarily increases thrombotic risk. 1, 2

Common pitfall: Using bridging therapy with direct oral anticoagulants—this is not recommended as DOACs have predictable short half-lives. 1 However, acenocoumarol as a VKA requires the full 5-day washout period. 1