Perioperative Anticoagulation Bridging: When, Why, and How?

Visual Element: An interactive "Bridging Calculator". User inputs patient risk factors (Mechanical Valve, AF stroke risk) and surgery bleeding risk to get a "Bridge / No Bridge" recommendation.

Managing anticoagulation in the peri-operative period is high-stakes poker. Stop the drugs too early, and the patient has a catastrophic stroke or valve thrombosis. Stop them too late (or bridge unnecessarily), and you cause a spinal hematoma or a infected joint hematoma requiring washout.

The old dogma was simple: "Admit everyone on Warfarin 5 days early and bridge with Heparin." This is wrong. The BRIDGE trial (2015) and subsequent studies have shown that for most patients (especially Atrial Fibrillation), bridging causes more harm (bleeding) than good (stroke prevention).

This guide outlines the modern, risk-stratified approach.

Part 1: Warfarin (Vitamin K Antagonists)

Warfarin is tricky because of its long half-life (36-42 hours) and variability.

To Bridge or Not to Bridge?

You must stratify the patient's Thromboembolic Risk.

High Risk (MUST BRIDGE):

• Mechanical Heart Valves: Mitral valve prostheses (any), or older Aortic valves (caged-ball/tilting disc). Recent stroke (<6 months).
• Atrial Fibrillation: CHADS2 score 5 or 6. Recent stroke/TIA (<3 months). Rheumatic valvular heart disease.
• VTE: DVT or PE within the last 3 months. Severe thrombophilia (e.g., Protein C deficiency).

Moderate Risk (Consider Bridging - Clinical Judgement):

• AF: CHADS2 score 3-4.
• VTE: History of VTE 3-12 months ago.

Low Risk (DO NOT BRIDGE):

• AF: CHADS2 score 0-2.
• VTE: Remote history (>12 months).
• Mechanical Valve: Bileaflet Aortic valve without other risk factors.

The Protocol

• Day -5: Stop Warfarin.
• Day -3: Start Therapeutic Enoxaparin (Clexane) 1mg/kg BD IF bridging.
• Day -1: Check INR. If > 1.5, give Vit K 1-2mg orally. Stop Clexane 24 hours pre-op.
• Day 0: Surgery.
• Day +1: Restart Warfarin (usual dose). Restart Clexane (prophylactic or therapeutic dose depending on surgical bleeding risk) until INR therapeutic.

Part 2: Direct Oral Anticoagulants (DOACs)

Apixaban (Eliquis), Rivaroxaban (Xarelto), Dabigatran (Pradaxa). These agents have short half-lives (~12 hours). Bridging is NEVER indicated for DOACs. The "bridge" is simply the pharmacokinetic washout.

Stopping Rules (Normal Renal Function)

• Low Bleeding Risk Procedure (Arthroscopy, Hand, Foot):
  • Stop 24 hours prior (skip 2 doses).
• High Bleeding Risk Procedure (Arthroplasty, Spine, Revision):
  • Stop 48-72 hours prior (skip 4-6 doses).

The Renal Trap

DOACs are renally cleared (Dabigatran >80%). In renal failure, the half-life extends massively.

• Dabigatran: If CrCl < 50 mL/min, stop 4 days prior to high-risk surgery.
• Apixaban/Rivaroxaban: Less dependent, but extend to 72 hours if CrCl < 30.

Part 3: Neuraxial Anaesthesia (Spinal/Epidural)

This is the surgeon's blind spot. You might be happy to operate, but the anaesthetist will refuse the spinal. An epidural hematoma leads to paraplegia. ASRA Guidelines are the bible here.

Part 4: Antiplatelet Agents

Elective Surgery

• Aspirin: generally CONTINUED for most cardiac patients. The risk of cardiac events upon cessation outweighs the mild increase in surgical bleeding. Exception: Intracranial/Spine surgery (surgeon preference).
• Clopidogrel / Ticagrelor: Stop 5-7 days prior.

The Coronary Stent Patient

• Bare Metal Stent: Elective surgery delayed for 4-6 weeks.
• Drug Eluting Stent (DES): Elective surgery delayed for 6-12 months (minimum 6 months).
• The Danger Zone: If you must operate within this window (e.g., hip fracture), DO NOT STOP ASPIRIN. Consult cardiology regarding the P2Y12 inhibitor (Clopidogrel). Often, we bridge with short-acting IV agents (Tirofiban) or continue DAPT if the bleeding risk is manageable. Stent thrombosis has a 50% mortality.

Part 5: Emergency Reversal

You are in the trauma bay. Patient has a bleed on Xarelto. What do you do?

1. Tranexamic Acid (TXA): 1g IV. Give it to everyone.
2. Specific Reversal Agents:
   • Idarucizumab (Praxbind): Specifically for Dabigatran. Instant reversal.
   • Andexanet Alfa: For Apixaban/Rivaroxaban. (Expensive, less available).
   • Prothrombinex (PCC): Factors II, IX, X. The standard for Warfarin reversal (along with Vit K). Also used off-label for Apixaban/Rivaroxaban bleeders.

Conclusion

The art of peri-operative medicine is minimizing the "Time at Risk."

• Minimize the time off drugs to prevent clots.
• Minimize the drug effect during surgery to prevent bleeds.
• Stop Bridging low-risk patients.

ASRA Guidelines App

Download the official ASRA Coags app for real-time guidance on neuraxial anesthesia intervals.