1. A Case of HIT?
Heparin Induced Thrombocytopenia
John R. Martinelli, OD, FAAO
MD Candidate 14’, SGUSOM
St. Barnabas Medical Center
Department of Transplant Medicine
Livingston, NJ
6/20/14

2. HPI
• 43yo Caucasian Male
• SPK 5/5/14 (Discharged 5/16/14)
• ESRD, DMI, HTN, HLD, PVD, AVR/Endocarditis
• HD/PD

3. HPI
• ED 5/22/14
• Weakness, Lethargy, Nausea, Melena,
Decreased UO, Dysuria, LLQ Pain
• 111/56, 89, 20, 98.3, 97% RA
• Hgb 5.5, Platelets 102, INR 2.4

4. HPI
• Xferred to ICU -> ?GI bleed
• GI bleed @ small bowel anastomotic site
confirmed via bleeding scan
• Post-op GI bleed in setting of PO coumadin tx
• d/c Coumadin, 4U PRBC, 2U FFP, IV Vit K

5. HPI
• ICU 5/24/14
– Hgb 9.0
• ICU 5/25/14
– Hgb 9.2
• Downgraded to floor 5/26/14
• IV Heparin started due to mechanical AVR

6. HPI
• 5/29 (x 3 days IV Heparin)
• Elevated PTT >60
• Hgb 9.9 -> 8.9
• D/C Heparin, Recheck PTT/Hgb, ½ Rate @ PTT
goal (50-60)

7. HPI
• Complicated Hospital Course
– Abdominal & Pelvic Ascites (SAAD & Cr WNL)
– Hypotensive episodes
– Acute Renal Injury (ATN vs Renal Toxicity)
– Varying Hgb levels
– Varying INR
– RLE pain

8. HPI
• 6/11 Platelets @ 31 (11 Days IV Heparin)
– HIT Assay (+)
– LDH/Hapto WNL (calcineurin)
– d/c Heparin
– FFP/Platelets (->99)
– No evidence of thrombotic or hemorrhagic event

9. 4T’s

10. 4T’s
• Score Range 0 -> 8
– 0 -> 3 Low Probability (.998 NPV)
– 3 -> 6 Intermediate Probability
– 6 -> 9 High Probability (.64 PPV)

11. 4T’s
• Our Patient
– Thrombocytopenia > 50% = 2pts
– Timing approximately 11 days = 1pt
– Thrombosis not evident = 0pts
– AlTernative cause possible = 1pt
» Total = 4pts = Intermediate Risk

12. Coagulation Cascade

13. HIT Types
• Type 1
– Fall in platelet count < 2 days from administration
– Return to normal
– No clinical consequence
– Non-immune, theorized transient platelet
interference
• Type 2
– Antibody mediated -> Heparin-Platelet Factor 4

14. Type 1 vs Type 2

15. Heparin
• Unfractionated Heparin vs LMWH
– IV or SubQ
• LMWH
– Enoxaparin
– Dalteparin
– Tinsaparin

16. HIT Signs & Symptoms
• Thrombocytopenia (5- 14 days)
• PTT, PT/INR not affected
• Serology: HIT ELISA -> Serotonin Release Assay (SRA)
• Thrombosis, Emboli, or Hemorrhage (A/V)
– Acute focal neurologic deficits (Stroke)
– Acute MI
– DVT
– PE
– Petechia, Purpura, Ecchymosis

17. HIT Mechanism
• Heparin Sulfate binds to Platelet Factor-4
• Antigenic
• IgG x 5 days -> IgG+PF4+Fc -> Lysis
– Thromboxane A2 -> GPIIb/IIIa
• Platelet aggregation and thrombosis/heme

18. HIT Treatment
• r/o Other Cause
• D/C Heparin
• Platelets/FFP/Vit K
• Alternatives
– Our px w/AVR
• Apixiban
• Dabigatran
• Fondaparinux

19. Thank You