Treatment of refractory delayed onset heparin-induced thrombocytopenia after thoracic endovascular aortic repair with intravenous immunoglobulin (IVIG).

Delayed onset heparin induced thrombocytopenia (HIT), is characterized by a late nadir due to persistent platelet-activating IgG antibodies. It typically begins or worsens 5 or more days after heparin is discontinued with complications such as thrombosis up to 3 weeks after exposure to heparin. In 50% of cases, the platelet count can decrease to very low numbers (<20 000/μL), which is not usual for typical HIT. Here we report 2 cases of post-operative delayed onset HIT manifesting as severe thrombocytopenia that persisted despite cessation of heparin and initiation of argatroban. Key Clinical Question: Is intravenous immunoglulin beneficial in severe refractory delayed-onset HIT?