SHM Converge Scientific Abstract ePoster Gallery-Thrombosis, Thrombocytopenia and Lupus Anticoagulant After Adenoviral Vector Vaccine

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A 53-year-old man developed extensive left-leg deep vein thrombosis and bilateral subsegmental pulmonary emboli after a trans-Atlantic flight. He also had thrombocytopenia, markedly elevated D-dimer, and a prolonged PTT that only partially corrected on mixing studies, suggesting an inhibitor. Lupus anticoagulant testing was strongly positive, while antiphospholipid antibodies, inherited thrombophilia testing, autoimmune workup, protein C, and protein S were normal.  <br /><br />Because he had received two doses of the ChAdOx1 nCoV-19 adenoviral COVID-19 vaccine six weeks earlier, vaccine-induced thrombotic thrombocytopenia (VITT) was considered. However, anti-platelet factor 4 (PF4) antibody testing was negative, which argues against typical VITT, as most definite or probable cases are PF4-positive. He was treated immediately with anticoagulation, initially low-molecular-weight heparin bridged to warfarin, then transitioned to rivaroxaban.  <br /><br />The report highlights that adenoviral vector vaccines have been associated with unusual thrombotic syndromes, likely related to PF4-mediated mechanisms, but this case suggests that thrombosis after vaccination may also occur with lupus anticoagulant positivity and without PF4 antibodies. The authors propose that vaccination may trigger a transient pro-inflammatory state that provokes lupus anticoagulant and thrombosis.  <br /><br />They recommend that lupus anticoagulant be evaluated in patients with post-vaccine thromboembolism, alongside PF4 testing, especially in individuals with additional risk factors such as long-haul travel. More evidence is needed to guide anticoagulation duration and to determine whether repeat PF4 or lupus anticoagulant testing is useful.

Asset Subtitle

Medha R. Cherabuddi

Meta Tag

Author List Medha R. Cherabuddi, Vijayalakshmi Donthireddy, Zaid Al Saheli

Category Clinical Vignettes

Concept Vaccine-associated Thrombotic Thrombocytopenia

Concept Thrombosis

Concept Thrombocytopenia

Concept Adenoviral Vector Vaccine

Concept Platelet Factor 4

Distinguished Non-Finalist

Presenter Organization Henry Ford Hospital, Detroit, MI

Presenting Author Medha R. Cherabuddi

Track Adult

Keywords

deep vein thrombosis

pulmonary embolism

lupus anticoagulant

thrombocytopenia

VITT

ChAdOx1 nCoV-19

PF4 antibody

adenoviral vaccine

anticoagulation

thromboembolism

Vaccine-associated Thrombotic Thrombocytopenia

Thrombosis

Thrombocytopenia

Adenoviral Vector Vaccine

Platelet Factor 4