Perioperative Anticoagulation Management

Risk Stratification - Balancing Act

• Core Principle: Balance clot risk (thrombosis) vs. surgical bleeding risk.
• Thrombotic Risk (Patient Factors):
  • High: Mech. mitral valve; AF (CHADS2-VASc ≥4); VTE <3 mo.
  • Moderate: AF (CHADS2-VASc 2-3); VTE 3-12 mo.
  • Low: AF (CHADS2-VASc 0-1); VTE >12 mo.
• Bleeding Risk (Procedure & Patient Factors):
  • High: Major surgery (cardiac, neuro); HAS-BLED ≥3; prior major bleed.
  • Low: Minor procedures (dental, cataract).
• Decision: Individualize. Bridging for high thrombotic risk if bleeding risk acceptable.

  ⭐ Premature anticoagulation cessation in high thrombotic risk patients (e.g., mechanical mitral valve) without bridging can be catastrophic.

Anticoagulant Drugs - Pills & Pokes

• Vitamin K Antagonists (VKAs) - e.g., Warfarin (Oral)

  • Mech: Inhibits Vit K-dependent factors (II, VII, IX, X).
  • Monitor: INR (Target 2-3).
  • Stop: 3-5 days pre-op. Bridge if high risk. 📌 Warfarin Wears Off Slowly.
  • Reversal: Vit K, FFP, PCC.

  ⭐ INR > 1.5 is a relative contraindication for neuraxial anesthesia.

• Heparins (Parenteral)

  • Unfractionated Heparin (UFH)
    • Mech: Potentiates Antithrombin (AT); inactivates IIa, Xa.
    • Monitor: aPTT (Target 1.5-2.5x control).
    • Stop IV: 4-6 hrs pre-op.
    • Reversal: Protamine Sulfate (1mg per 100U UFH).
  • Low Molecular Weight Heparin (LMWH) - e.g., Enoxaparin
    • Mech: Potentiates AT; mainly inactivates Xa > IIa.
    • Stop: Prophylactic dose 12 hrs pre-op; Therapeutic dose 24 hrs pre-op.
    • Reversal: Protamine Sulfate (partial).

• Direct Oral Anticoagulants (DOACs) (Oral)

  • Direct Thrombin Inhibitors - e.g., Dabigatran
    • Stop: 24-96 hrs pre-op (depends on renal function & bleed risk).
    • Reversal: Idarucizumab.
  • Factor Xa Inhibitors - e.g., Rivaroxaban, Apixaban
    • Stop: 24-72 hrs pre-op (depends on drug, renal function & bleed risk).
    • Reversal: Andexanet Alfa (for rivaroxaban, apixaban).

Preoperative Planning - Stop & Swap

• Goal: Minimize bleeding, prevent thromboembolism.
• Assess: Surgical bleeding risk vs. patient thrombotic risk.

Drug-Specific Protocols:

• Warfarin (VKA):
  • Stop 5 days pre-op. Target INR < 1.5.
  • Bridge if high thrombotic risk (e.g., mechanical valve, recent VTE).
    • LMWH: Stop 24h (therapeutic dose), 12h (prophylactic dose).
    • UFH: Stop 4-6h pre-op.
• DOACs (Direct Oral Anticoagulants):
  • Dabigatran: Stop 48-96h pre-op (longer if CrCl < 50 ml/min).
  • Factor Xa Inhibitors (Rivaroxaban, Apixaban, Edoxaban): Stop 24-72h pre-op.
• Antiplatelets:
  • Aspirin: Continue if minor surgery & high CV risk. Stop 3-7 days if needed.
  • Clopidogrel: Stop 5 days pre-op.
  • Ticagrelor: Stop 3-5 days pre-op.
  • Prasugrel: Stop 7 days pre-op.

⭐ For patients on warfarin with a mechanical heart valve, bridging with LMWH/UFH is crucial to prevent valve thrombosis.

Flowchart: General Approach

Postoperative Resumption - Go Time Again

• Goal: Balance thrombotic vs. bleeding risk. Resume once hemostasis is adequate.
• General Timing (post-op):
  • Low Bleeding Risk Surgery:
    • Prophylactic anticoagulation (AC): ~24 hrs.
    • Therapeutic AC: 24-48 hrs (if no active bleed).
  • High Bleeding Risk Surgery:
    • Prophylactic AC: ~48 hrs.
    • Therapeutic AC: 48-72 hrs (ensure hemostasis).
• Agent-Specific Notes:
  • Warfarin: Resume usual dose evening of surgery or Post-Operative Day (POD) 1 (low bleed risk). Monitor INR.
  • Direct Oral Anticoagulants (DOACs): Resume 24 hrs (low risk) or 48-72 hrs (high risk).
  • Low Molecular Weight Heparin (LMWH)/Unfractionated Heparin (UFH) (therapeutic doses): Resume 24-72 hrs. Consider initial half-dose if high bleeding risk.

⭐ When resuming warfarin post-op with bridging: restart parenteral AC 12-24 hrs after surgery (if hemostasis adequate) alongside warfarin. Continue parenteral AC until INR is therapeutic (2.0-3.0) for at least 2 consecutive days.

High-Yield Points - ⚡ Biggest Takeaways

• Stop Warfarin 5 days pre-op; bridge with LMWH/UFH for high thrombotic risk.
• Stop DOACs 24-72h pre-op, considering renal function & bleed risk.
• Aspirin for secondary prevention often continued; stop 7 days prior for primary if high bleed risk.
• Stop Clopidogrel 5-7 days before major surgery.
• Neuraxial anesthesia demands strict anticoagulant timing to prevent spinal hematoma.
• Bridge high-risk patients (e.g., mechanical valves, recent VTE, high-risk AFib); restart 24-72h post-op once hemostasis secured.