Direct Oral Anticoagulants as Primary or Secondary Treatment for Heparin‐Induced Thrombocytopenia (HIT) and Associated Thromboembolism (HITT)—A Meta‐Analysis

INTRODUCTION: Heparin-induced thrombocytopenia (HIT) is associated with a high risk for thrombosis. The role of direct oral anticoagulants (DOACs) is still emerging and data are limited considering efficacy and safety among patients with HIT. The aim of this review is to evaluate current data on DOACs as primary or secondary treatment among patients with HIT. METHODS: This is a systematic review utilising Pubmed, Scopus and Embase online databases. Eligible studies were published up to December 2024 evaluating DOACs as primary or secondary treatment among patients with HIT and/or associated thrombosis (HITT). Primary outcomes included thrombosis rate (TR) and bleeding rate (BR) during follow-up. RESULTS: A total of 44 publications were included (29 case reports, 5 case studies and 10 cohort studies [n > 10 patients]). Regarding treatment, 19 articles evaluated only rivaroxaban, 7 articles only apixaban, 11 articles only dabigatran and 7 articles more than one regimen. A total of 352 patients were included. Overall, 190 patients (53.8%) were given DOAC as primary treatment whereas 162 patients were given a parenteral treatment first and continued with a DOAC. Mean nadir platelet count at diagnosis was 63 000/μL. HITT rate was 190/352 (53.9%; 8% had arterial thrombosis). Mean follow-up was 7.6 months. TR was 20/352 (Pooled proportion = 0.064 [95% CI = 0.042-0.092]) (30% of them were new thromboses without initial thrombosis), and BR was 9/352 (Pooled proportion = 0.039 [95% CI = 0.022-0.062]). Finally, there was no difference found regarding TR and BR between primary or secondary treatment, and among different regimens. CONCLUSIONS: DOACs are associated with low rates of thrombosis and major bleeding among patients treated for HIT or HITT, either as primary or secondary treatment. However, the certainty of evidence is very low because of the quality and limitations of the available studies.