4T Score
- Recall, for thrombosis the event can be arterial (e.g. MI) or venous (e.g. DVT)
- Interpretation
- 0-3 (low risk) → HIT unlikely → monitor platelets
- 4-5 (moderate risk) → HIT possible → stop 🚫 heparin
- ≥6 (high risk) → HIT likely → stop 🚫 heparin
Treatment
- Stop all heparin
- Obtain platelet factor 4 antibody testing (or SRA for confirmation)
- 📝 Sometimes SRA can take ~1 week to get result. PF4 Ab results faster.
- Start direct thrombin inhibitor
- Argatroban (⚠️ hepatic excretion)
- Bivalirudin
- Warfarin (after platelet count recovery)
- DOAC
- 📝 Place heparin on allergy list