Platelet dynamics and clinical outcomes in patients with heparin-induced thrombocytopenia – single center experience

Abstract INTRODUCTION Heparin-induced thrombocytopenia (HIT) is a life-threatening condition that requires immediate diagnosis and treatment with alternative (non-heparin) anticoagulants. Several agents, such as bivalirudin, argatroban, danaparoid, and fondaparinux, have been used for the treatment of HIT. However, in Bulgaria, we currently have access only to fondaparinux for off-label use in these patients. Here, we present our experience by comparing platelet dynamics and clinical outcomes in a cohort of 49 patients diagnosed with HIT. MATERIALS AND METHODS Data were retrospectively collected from patients diagnosed with HIT from January 2020 to June 2024 in the National Hospital of Cardiology in Sofia, Bulgaria. Repeated measures ANOVA analysis was applied to assess the dynamics in platelet counts at three different time points: before, at the onset, and after HIT diagnosis. Overall survival (OS) was estimated using the Kaplan-Meier method. RESULTS In the entire HIT cohort (n=49), the median age was 68 years, and 38.8% of the patients were female. The majority of patients (38.8%) were diagnosed in the cardiac surgery department, followed by cardiology (30.6%), ICU (24.5%), and vascular surgery (6.1%). Heparin was stopped at HIT diagnosis in all patients. Alternative anticoagulation with fondaparinux was started in 36 patients (73.5%), whereas 10 (20.4%) did not receive any alternative anticoagulation, and three patients (6.1%) were directly switched to oral anticoagulants. We compared platelet counts in those treated with an alternative anticoagulant versus those not treated. In the treatment group, platelet counts were significantly higher before, at the time of, and after diagnosis of HIT (p < 0.001). No bleeding episodes were reported in both groups. Importantly, 17 patients (34%) died during the observation period, with the highest mortality rate in HIT-positive patients in the ICU department. There was a significantly inferior OS in the non-treatment group (p < 0.0001). CONCLUSION Treatment with alternative anticoagulants besides cessation of heparin is crucial in patients with HIT. Our data support the off-label use of fondaparinux as an effective and safe alternative anticoagulant. The dynamics of platelet counts after diagnosis may be an important tool for assessing treatment efficacy. Despite treatment, the mortality rate in critically ill patients with HIT remains high.