Heparin-Induced Thrombocytopenia and Thrombosis in Patients With or Without a Thrombophilia Background: A Systematic Review Involved 602 Cases.

Background: Heparin-induced thrombocytopenia (HIT), often accompanied by thrombotic events and collectively referred to as heparin-induced thrombocytopenia and thrombosis (HITT), is worthy of attention. Herein, we analyzed the features of HITT in patients with or without a thrombophilia background present prior to heparin exposure, aiming to identify and customize treatment. Methods: We searched PubMed and EMBASE to identify studies published up to November 2024, via the keywords "heparin," "thrombocytopenia," "thrombosis," and "thrombophilia." Case series and reports with confirmed HITT were included. Results: A total of 602 patients (277 males and 325 females with a mean age of 57.00 ± 17.20 years), reported in 481 papers, were carefully analyzed. The median time of thrombocytopenia and thrombosis onset postheparin exposure was Day 9 (5-12) and Day 9 (6-12), respectively. The abnormal platelet counts recovered by Day 5 (3-7) after the cessation of heparin. A more pronounced platelet count reduction was shown in patients with a thrombophilia background than those without this entity ( Conclusions: HITT typically presents as newly formed venous thrombosis in patients with a thrombophilia background and as arterial thrombosis in those without thrombophilia. Whereby, screening for thrombophilia in patients with HITT is suggested, as well as considering prolonged alternative anticoagulation therapy in patients with a thrombophilia background.