A patient is receiving heparin infusion post-cardiac surgery and develops heparin-induced thrombocytopaenia (HIT) with thrombosis on day 5. The platelet count has fallen from 280 to 60 × 10⁹/L. What is the MOST appropriate next step?

• A Stop heparin and administer platelet transfusion to maintain >50 × 10⁹/L
• B Stop heparin and start warfarin immediately
• C Reduce heparin dose by 50% and recheck platelet count in 24 hours
• D Stop heparin and start argatroban or bivalirudin ✓

Explanation

HIT type II is an immune-mediated, prothrombotic condition caused by antibodies against heparin-PF4 complexes. All heparin must be stopped immediately (including heparin flushes and LMWH). Because of the extreme thrombotic risk, a non-heparin anticoagulant (direct thrombin inhibitor) such as argatroban or bivalirudin must be started. Warfarin is contraindicated acutely because it depletes protein C first, worsening hypercoagulability and risking limb gangrene. Platelet transfusions are relatively contraindicated as they may fuel thrombosis ('fuel on the fire').

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.