anti-heparin/platelet factor 4 antibodies, cardiopulmonary bypass surgery, flow cytometry assay, heparin-induced thrombocytopenia, Medicine (General), R5-920

There are few studies on heparin-induced thrombocytopenia (HIT) reported from Taiwan and Asian countries. We conducted a prospective study to investigate the frequency of HIT in patients undergoing cardiopulmonary bypass surgeries. Methods: A cohort of 54 patients was enrolled from January 01, 2010 to October 31, 2011. Patients' clinical information was obtained for 4T score classification. Plasma (2–4 mL) was also collected before surgery and on Days 5 and 10 following heparin administration during the bypass procedure. This was tested for anti-heparin/PF4 antibodies and functional assay using flow cytometry (FC). Results: The mean platelet count for this cohort followed the expected pattern in the postoperative setting. Seven of the 54 (13%) patients had positive antibodies assays before bypass surgery. This increased to 32% on Day 5 and was markedly elevated to 63% on Day 10 after surgery. Only one of the 54 patients (1.8%) was found to have both positive antibody assay and platelet activation, but no clinical HIT/thrombosis developed. Conclusion: Our study is the first report on the rates of HIT in the setting of cardiopulmonary bypass surgery in Taiwan and demonstrated no clinical HIT occurrence, despite the high frequency of HIT antibody in our cohort.