Perioperative Anticoagulation Management

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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.

Practice Questions: Perioperative Anticoagulation Management

Test your understanding with these related questions

A 20-year-old woman with a family history of von Willebrand disease is found to have an activated partial thromboplastin time (aPTT) of 78 (normal = 32) on routine testing prior to cholecystectomy. Further investigation reveals a prothrombin time (PT) of 13 (normal = 12), a platelet count of 350,000/mm³, and an abnormal bleeding time. Which of the following should be administered in the perioperative period?

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Flashcards: Perioperative Anticoagulation Management

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A patient with well controlled DM/HTN would be classified under ASA _____

TAP TO REVEAL ANSWER

A patient with well controlled DM/HTN would be classified under ASA _____

II

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