Cardiovascular · Year 1 · from Cardiovascular

Case 3: Warfarin Reversal - Anticoagulation Emergency

Clinical Image

Source: Wikimedia Commons - Warfarin mechanism - CC BY-SA 4.0

Patient Presentation

A 72-year-old man on warfarin for atrial fibrillation falls at home and strikes his head on the floor. He is brought to the emergency department by ambulance after his wife found him confused with a large scalp laceration. He took his warfarin dose this morning and cannot recall how much.

Demographics

  • Age: 72 years
  • Sex: Male
  • Past Medical History: Atrial fibrillation, mechanical mitral valve replacement (5 years ago), hypertension
  • Medications: Warfarin 7.5 mg daily (target INR 2.5-3.5 for mechanical valve), lisinopril, metoprolol

Chief Complaint

Fall with head trauma and confusion

Physical Examination

  • Blood pressure: 168/92 mmHg
  • Heart rate: 82 bpm (irregularly irregular)
  • GCS: 13 (E3V4M6)
  • General: Confused, large scalp laceration with active bleeding
  • Pupils: Left 4 mm, right 3 mm, both reactive but sluggish
  • Cardiovascular: Irregular rhythm, mechanical click audible
  • Neurological: Left-sided weakness (right hemiparesis), difficulty speaking

Workup

  • INR: 4.8 (supratherapeutic)
  • PT: 52 seconds
  • Hemoglobin: 10.2 g/dL
  • Platelet count: 178,000/μL
  • CT head (non-contrast): Right-sided acute subdural hematoma with 8 mm midline shift

Diagnosis

Traumatic Intracranial Hemorrhage (Subdural Hematoma) in setting of Supratherapeutic Anticoagulation

Treatment

  1. Emergent INR reversal:
  • 4-Factor Prothrombin Complex Concentrate (4F-PCC) 50 units/kg IV
  • Preferred over FFP for speed and volume
  • Repeat INR in 15-30 minutes (target INR <1.5)
  1. Vitamin K 10 mg IV (slow infusion to prevent anaphylaxis)
  • Works over 6-24 hours; PCC provides immediate reversal
  1. Neurosurgery consultation for potential surgical evacuation
  2. Blood pressure control (target SBP <140 mmHg)
  3. Avoid antiplatelet agents
  4. Post-stabilization: Discuss long-term anticoagulation strategy given mechanical valve (cannot remain off anticoagulation indefinitely)
  5. Home safety evaluation before discharge

Physiological Principles Demonstrated

  • Warfarin mechanism: Warfarin inhibits vitamin K epoxide reductase (VKORC1), preventing recycling of vitamin K. This impairs hepatic synthesis of factors II, VII, IX, and X (and proteins C and S).
  • Factor half-lives: Factor VII has the shortest half-life (~6 hours), so PT/INR rises first. Full anticoagulant effect takes 3-5 days as all factors decline.
  • 4F-PCC vs. FFP: 4F-PCC provides concentrated clotting factors (II, VII, IX, X) in small volume with rapid administration. FFP requires large volumes, thawing time, and risks volume overload.
  • Vitamin K importance: PCC provides temporary factor replacement; vitamin K is needed to restore hepatic synthesis of clotting factors for sustained reversal.
  • Mechanical valve considerations: Mechanical valves have high thrombotic risk without anticoagulation. After stabilization, anticoagulation must be resumed, often with bridging strategies.

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