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Heparin-Induced Thrombocytopenia — FRCA Final MCQ

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HardIntensive Care MedicineHeparin-Induced ThrombocytopeniaFRCA Final

A 62-year-old man remains critically ill in the ICU after cardiac surgery. He is receiving an unfractionated heparin infusion, with an aPTT ratio of 2.5. His platelet count has fallen from 180 to 55 × 10⁹/L. His 4Ts score is 7, and both an anti-PF4/heparin immunoassay and a functional platelet-activation assay are positive. He has no active bleeding and no severe hepatic impairment. Which is the most appropriate immediate management?

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Correct answer: B — Discontinue all heparin; once the residual heparin effect on aPTT has declined, commence reduced-dose argatroban and titrate using aPTT

The correct answer is B. Confirmed immune-mediated HIT is intensely prothrombotic, so all heparin—including flushes and heparin-coated sources—must be stopped and therapeutic non-heparin anticoagulation started; thrombocytopenia alone is not a reason to observe. Argatroban is a licensed direct thrombin inhibitor suitable here. Because he is critically ill following cardiac surgery, the SmPC supports starting at 0.5 microgram/kg/min, after allowing residual heparin-related aPTT prolongation to decline, then titrating to 1.5–3.0 times baseline without exceeding 100 seconds. Warfarin must not be initiated during acute thrombocytopenia because rapid protein C depletion may cause microvascular thrombosis and venous limb gangrene. Prophylactic platelet transfusion is generally avoided; it may be considered for clinically important bleeding or an urgent invasive procedure. Reducing rather than stopping heparin leaves the pathogenic stimulus in place.

Reference: Ethypharm UK Ltd. Exembol 1 mg/ml Solution for Infusion, Summary of Product Characteristics, sections 4.1–4.4; text revised 31 October 2024. https://www.medicines.org.uk/emc/product/16026/smpc