Outcomes of patients with suspected heparin-induced thrombocytopenia in a contemporary multicenter cohort.

Managing patients with suspected heparin-induced thrombocytopenia (HIT) poses significant clinical challenges. Limited evidence exists on how management decisions impact clinical outcomes, leading to treatment recommendations based on low-certainty evidence. This study aimed to evaluate the treatment strategies and clinical outcomes of patients with suspected HIT in a contemporary multicenter cohort. We conducted a prospective, multicenter cohort study including consecutive patients with suspected HIT from 11 centers. Patients were stratified into 3 groups: (1) HIT confirmed, (2) HIT-negative but heparin/platelet factor 4 (PF4) antibody-positive, and (3) HIT-negative without antibodies. Clinical and laboratory data were systematically collected. HIT was diagnosed using the washed-platelet heparin-induced platelet activation test as the reference standard. Among 1393 patients (46% female, median age 67 years), HIT was confirmed in 119 (8.5%). Most patients were in intensive care (37%), or had undergone cardiac surgery (32%). Argatroban was the predominant treatment (70%), and platelet recovery occurred in 77% of patients with HIT. Among patients with HIT, subsequent venous thromboembolism occurred in 23%, arterial thromboembolism in 9%, major bleeding in 12.6%, and mortality in 18%, with no significant differences between anticoagulants. Treatment with argatroban, bivalirudin, or direct oral anticoagulants (DOACs) significantly reduced arterial thromboembolism risk. Outcomes did not differ between patients who were HIT-negative with or without heparin/PF4 antibodies. HIT, as well as the mere suspicion of HIT, remains a serious condition with a high risk of adverse outcomes, including death. Our findings provide further evidence supporting the effectiveness of DOACs, argatroban, and bivalirudin in reducing arterial thromboembolism risk.