Safety of antithrombotic therapy in hereditary hemorrhagic telangiectasia: results from a prospective cohort study.

Background: Hereditary hemorrhagic telangiectasia (HHT) is a vascular disorder characterized by a predominant bleeding phenotype. However, patients are also at risk of thrombotic events and may require antithrombotic therapy (AT), for which safety data remain limited. Objectives: To prospectively evaluate the safety of AT in patients with HHT using standardized longitudinal assessment of bleeding outcomes. Methods: We conducted a prospective observational study at a tertiary HHT referral center. Patients with a definite diagnosis of HHT and a new indication for antiplatelet or anticoagulant therapy were enrolled. The primary outcome was the incidence of hemorrhagic events, classified according to the International Society on Thrombosis and Haemostasis criteria. Secondary outcomes included worsening of epistaxis assessed by the Epistaxis Severity Score, changes in hemoglobin levels, and transfusion requirements. Results: A total of 33 patients (mean age 65.8 ± 12.9 years; 69.7% male) were included, for a total of 41 AT courses. During a mean follow-up of 21.1 ± 19.2 months, 2 major bleeding events (4.9%) occurred, both during anticoagulant therapy. Three clinically relevant nonmajor bleeds and one minor bleed were recorded. Worsening of epistaxis occurred in 24.4% of treatment courses, but mean Epistaxis Severity Score values did not differ from baseline. Hemoglobin levels and transfusion requirements were not significantly affected. Conclusions: In this prospective cohort, AT was associated with an acceptable safety profile in selected patients with HHT managed in a multidisciplinary setting. These findings strengthen the currently limited prospective evidence supporting individualized antithrombotic management in HHT, although larger multicenter prospective studies remain warranted.