Faculty of Health Sciences, McMaster University, Hamilton, ON, Canada.
Divisione di Medicina Generale II, ASST Santi Paolo e Carlo, Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy.
Int J Hematol. 2023 Mar;117(3):341-348. doi: 10.1007/s12185-022-03516-4. Epub 2022 Dec 27.
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a highly prothrombotic disorder caused by anti-PF4 antibodies that activate platelets and neutrophils, leading to thrombosis. Heparin-induced thrombocytopenia (HIT) is a related anti-PF4 mediated disorder, with similar pathophysiology and clinical manifestations but different triggers (i.e., heparin vs adenoviral vector vaccine). Clinically, both HIT and VITT typically present with thrombocytopenia and thrombosis, although the risk of thrombosis is significantly higher in VITT, and the thromboses occur in unusual anatomical sites (e.g., cerebral venous sinus thrombosis and hepatic vein thrombosis). The diagnostic accuracy of available laboratory testing differs between HIT and VITT; for VITT, ELISAs have better specificity compared to HIT and platelet activation assays require the addition of PF4. Treatment of VITT and HIT is anticoagulation non-heparin anticoagulants; however, heparin may be considered for VITT if no other option is available.
疫苗诱导的免疫性血栓性血小板减少症（VITT）是一种由抗 PF4 抗体引起的高度血栓形成性疾病，可激活血小板和中性粒细胞，导致血栓形成。肝素诱导的血小板减少症（HIT）是一种相关的抗 PF4 介导的疾病，具有相似的病理生理学和临床表现，但触发因素不同（即肝素与腺病毒载体疫苗）。临床上，HIT 和 VITT 通常都表现为血小板减少和血栓形成，尽管 VITT 中血栓形成的风险显著更高，而且血栓形成发生在不常见的解剖部位（例如，脑静脉窦血栓形成和肝静脉血栓形成）。现有的实验室检测在 HIT 和 VITT 之间的诊断准确性不同；对于 VITT，ELISA 比 HIT 具有更好的特异性，血小板激活试验需要添加 PF4。VITT 和 HIT 的治疗方法均为抗凝非肝素抗凝剂；然而，如果没有其他选择，肝素可考虑用于 VITT。
