Persisting autoimmune heparin-induced thrombocytopenia after elective abdominal aortic aneurysm repair: a case report

Abstract

Persisting heparin-induced thrombocytopenia (HIT) is characterized by ongoing thrombocytopenia more than 7 days after stopping heparin. It is part of cases referred to as autoimmune HIT (aHIT). In contrast to typical HIT cases, aHIT involves heparin-independent platelet activation mechanism highlighted by a strongly positive functional assay done without heparin. We report the first case of persisting HIT after an elective abdominal aortic aneurysm repair presenting with arterial and venous thrombosis, and describe the potential role of intravenous immunoglobulin in such patients. Keywords Case report • Heparin • Thrombocytopenia • Thrombosis • Immunoglobulin Highlights• Ongoing thrombocytopenia more than 7 days after stopping heparin and new thrombosis despite receiving treatment characterize persisting HIT. • Autoimmune HIT is characterized by a strongly positive functional assay done without heparin. • Intravenous immunoglobulin for treatment of autoimmune HIT results in improvement of thrombocytopenia and the most used dosing schedule is 1 g/kg daily for 2 doses.• Intravenous immunoglobulin should be considered as an emerging therapy for autoimmune HIT.

Intravenous Immune Globulin (IVIG) for Treatment of Autoimmune Heparin-Induced Thrombocytopenia: A Systematic Review

“…8,14-16,23-30,33,34,36,37,40,41 Three patients had both arterial and venous thromboses at HIT diagnosis. 8,23,34 DIC was reported in 5 patients. 16,27,28,33,35 A total of 12 patients had a 4T score reported.…”

“…14,28,41 The data for these patients are included in Tables 2 and 3. 8,14-16,23-30,33-41 Data in Table 2 include age, sex, patient type, initial anticoagulant used, new thrombosis and bleeding complications at HIT diagnosis, 4T score, immunoassay OD, activation assay results, aHIT variant (delayed, flush-induced, fondaparinux-associated, persistent, spontaneous), anticoagulant for HIT treatment, and platelet nadir. Data in Table 3 include platelet nadir, IVIG dose(s), weight used to calculate dose (when available), product used (when available), post-IVIG platelet recovery (defined as an increase in platelets by at least 50 × 10 9 /L), thrombosis after IVIG administration, and highest platelet count post-IVIG.…”

“…14,16,23-30 In all, 92% of patients (n = 22/24) had an immunoassay completed (median OD = 2.75; range = 1.69 to 3.83). 14,15,23-30,33-41 Although 2 patients had an OD <2 and 2 patients did not report an immunoassay, all patients reviewed, except those from Huang et al 27 (OD = 3.68), had a positive activation assay (most of them used SRA). 8,14-16,23-30,33-41 Autoimmune HIT was confirmed in 9 patients by the use of SRA (reported positive SRA results at 0 IU/mL UFH or use of the PEA assay).…”

“…8,14,33 Gamunex/Gamunex-C was administered to 3 patients. 23,24,37 In the United States, Gamunex was originally FDA approved in 2003. 58 In 2010, Gamunex received FDA approval for subcutaneous administration for primary immunodeficiency, changing to Gamunex-C. Gamunex-C is the only Gamunex product currently marketed in the United States.…”

“…22 The 4T scoring tool was reported for some cases discussed in this review. 14,16,[23][24][25][26][27][28][29][30] A discussion of other scoring systems is beyond the scope of this article (see 2018 ASH guidelines). 13 The 4T score evaluates the following: (1) the relative decrease in platelet count, (2) the timing of the onset of platelet count decrease, (3) thrombosis present or absent, and (4) other causes to explain the fall in platelets.…”