A Case of HIT?Heparin Induced Thrombocytopenia

John R. Martinelli, OD, FAAOMD Candidate 14’, SGUSOMSt. Barnabas Medical CenterDepartment of Transplant MedicineLivingston, NJ6/20/14

HPI

• 43yo Caucasian Male

• SPK 5/5/14 (Discharged 5/16/14)

• ESRD, DMI, HTN, HLD, PVD, AVR/Endocarditis

• HD/PD

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

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

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

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)

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

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

4T’s

4T’s

• Score Range 0 -> 8

– 0 -> 3 Low Probability (.998 NPV)

– 3 -> 6 Intermediate Probability

– 6 -> 9 High Probability (.64 PPV)

4T’s

• Our Patient

– Thrombocytopenia > 50% = 2pts– Timing approximately 11 days = 1pt– Thrombosis not evident = 0pts– AlTernative cause possible = 1pt

» Total = 4pts = Intermediate Risk

Coagulation Cascade

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

Type 1 vs Type 2

Heparin

• Unfractionated Heparin vs LMWH– IV or SubQ

• LMWH– Enoxaparin– Dalteparin– Tinsaparin

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

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

HIT Treatment• r/o Other Cause

• D/C Heparin

• Platelets/FFP/Vit K

• Alternatives– Our px w/AVR

• Apixiban• Dabigatran• Fondaparinux

Thank You