Background
Prospective, multicenter, historical-controlled study (ARG-911). N=304 with heparin-induced thrombocytopenia (HIT, n=160) or HIT with thrombosis syndrome (HITTS, n=144) treated with argatroban vs 193 historical controls (HIT n=147, HITTS n=46). Argatroban is a synthetic direct thrombin inhibitor that reversibly binds the thrombin active site and does not cross-react with heparin-PF4 antibodies. HIT is an immune-mediated prothrombotic complication of heparin from anti-heparin-PF4 antibodies.
Interventions and follow up
Arm A (argatroban): Argatroban 2 µg/kg/min IV continuous infusion, adjusted to aPTT 1.5–3× baseline, in HIT (n=160) or HITTS (n=144)
Arm B (historical control): Heparin discontinuation alone without alternative anticoagulant; HIT (n=147) or HITTS (n=46)
Primary endpoint: Composite of all-cause death, all-cause amputation, or new thrombosis at 37 days
Median follow-up: 37 days
Arm B (historical control): Heparin discontinuation alone without alternative anticoagulant; HIT (n=147) or HITTS (n=46)
Primary endpoint: Composite of all-cause death, all-cause amputation, or new thrombosis at 37 days
Median follow-up: 37 days
Results
Composite endpoint (HIT patients): 25.6% (argatroban) vs 38.8% (historical control); P=.014
Composite endpoint (HITTS patients): 43.8% vs 56.5%; P=.13
Time to platelet recovery: Significantly faster with argatroban; P=.0001
New thrombosis: Significantly reduced vs historical control; P<.05
Therapeutic aPTT achieved: Within 4–5 hours of starting infusion
Composite endpoint (HITTS patients): 43.8% vs 56.5%; P=.13
Time to platelet recovery: Significantly faster with argatroban; P=.0001
New thrombosis: Significantly reduced vs historical control; P<.05
Therapeutic aPTT achieved: Within 4–5 hours of starting infusion
Adverse events
Bleeding: Similar between argatroban and historical controls
Major bleeding: ~6% (consistent with underlying disease severity)
Cross-reactivity: None with heparin-PF4 antibodies
Hepatic dosing: Hepatic impairment requires 4-fold dose reduction (hepatically metabolized)
Monitoring caveat: Prolongs PT/INR; account for during warfarin bridging (INR goal ≥4 on argatroban)
Major bleeding: ~6% (consistent with underlying disease severity)
Cross-reactivity: None with heparin-PF4 antibodies
Hepatic dosing: Hepatic impairment requires 4-fold dose reduction (hepatically metabolized)
Monitoring caveat: Prolongs PT/INR; account for during warfarin bridging (INR goal ≥4 on argatroban)
Conclusions
Argatroban significantly reduced the composite of death, amputation, or new thrombosis in HIT patients vs historical controls, with faster platelet recovery, establishing argatroban as a standard non-heparin anticoagulant for HIT.
Key Limitations
Historical (non-concurrent) controls rather than randomized, risking selection/temporal bias. HITTS composite did not reach significance (P=.13). Open-label. PT/INR prolongation complicates warfarin transition. Predates current immunoassay/SRA HIT diagnostics.
Clinical Context
Pivotal trial supporting FDA approval of argatroban for HIT. ASH 2018 guidelines recommend a non-heparin anticoagulant (argatroban, bivalirudin, danaparoid, fondaparinux, or DOAC) for acute HIT; argatroban is preferred in renal impairment given hepatic clearance.