This handout is for dvt/vte with heparin-induced thrombocytopenia (hit/hitt). Your care team identified this based on: ≥50% platelet count drop occurring 5-14 days after starting heparin (ufh or lmwh) — cardinal hit trigger; 4ts pretest probability.
Other reasons your team may use this plan: new venous or arterial thrombosis during or shortly after heparin exposure — strong hit signal even if platelets only mildly down; rapid-onset thrombocytopenia within hours of heparin exposure in patient with heparin within prior 30 days (re-exposure phenomenon — pre-existing hit antibodies); limb arterial occlusion, cerebral venous sinus thrombosis, or adrenal vein thrombosis with concurrent thrombocytopenia — pursue hit workup urgently.
Take these medications exactly as prescribed. Do not stop or change a dose without talking to your provider.
| Medication | Starting dose | How | When | What it does |
|---|---|---|---|---|
| argatroban | 2 mcg/kg/min IV (start 0.5 mcg/kg/min if hepatic impairment, multi-organ failure, or post-cardiac-surgery); titrate to aPTT 1.5-3× baseline (max 10 mcg/kg/min) | IV | continuous infusion | ASH 2018 (Cuker PMID 29914917); ACCP 2021 — first-line in critically ill, renal failure (no renal dose adjustment); short half-life ~45 min; reversal by stopping infusion |
| bivalirudin | 0.15 mg/kg/h IV (renal-adjusted: CrCl 30-60 → 0.1 mg/kg/h; CrCl <30 or HD → 0.05 mg/kg/h); titrate to aPTT 1.5-2.5× baseline | IV | continuous infusion | ASH 2018; bivalirudin half-life ~25 min; useful for short procedures (PCI, CPB) and in hepatic dysfunction; renal adjustment required |
| fondaparinux | 7.5 mg SC daily (5 mg if <50 kg; 10 mg if >100 kg) | SC | daily | ASH 2018 — fondaparinux acceptable for HIT (off-label but evidence supports); does not cross-react with HIT antibodies in vivo (OASIS-5 background, Yusuf NEJM 2006); avoid CrCl <30; no antidote |
| apixaban | 10 mg BID × 7 d → 5 mg BID | PO | BID ≥3 months for thrombosis | ASH 2018 — DOAC acceptable in stable HIT patients; ARC consensus 2020 (Cuker Blood Adv 2020); Linkins 2016 cohort + observational data; especially useful for transition from parenteral non-heparin AC and outpatient management |
| rivaroxaban | 15 mg BID × 21 d → 20 mg daily | PO | BID then daily ≥3 months | ASH 2018; alternative DOAC for stable HIT |
| warfarin | 5 mg PO daily; ONLY START after platelets recover ≥150K and overlap ≥5 d with non-heparin AC; INR target 2-3 | PO | daily ≥3 months | ASH 2018 — DO NOT start warfarin until platelets ≥150K and after 5-d non-heparin AC overlap; early warfarin precipitates VENOUS LIMB GANGRENE because protein C falls faster than factors II/IX/X; if warfarin started inadvertently before platelet recovery → reverse with vitamin K 5-10 mg PO/IV and continue non-heparin AC |
| vitamin_k_phytonadione | 5-10 mg PO or IV | PO or IV | one-time | ASH 2018 — reverse early-overlap warfarin if HIT diagnosed after warfarin started; restore protein C activity to abort venous limb gangrene |
Plan: Heparin-induced thrombocytopenia — STOP all heparin, non-heparin AC immediate, warfarin only after platelet recovery (ASH 2018; ACCP 2021)
Contact your care team if any of the following happen:
Call 911 or go to the nearest emergency room right away if you have:
Hematology long-term follow-up; ≥3 mo AC for thrombosis (longer if ongoing risk); LIFELONG heparin avoidance education (UFH + LMWH including bridging) — medical alert bracelet permanent; future cardiac surgery exposure plan (antibody re-testing at 100 d if elective surgery requires CPB)
Guideline: ASH 2018 Heparin-Induced Thrombocytopenia (Cuker) + ACCP/CHEST 2021 (Stevens) for AC duration