PO067 | LONG‑TERM SAFETY AND EFFECTIVENESS OF VITAMIN K ANTAGONISTS IN PATIENTS WITH ANTIPHOSPHOLIPID ANTIBODIES: A RETROSPECTIVE COHORT ANALYSIS

G. Sottilotta¹, G. Praticò¹, D. Megalizzi¹, F. Luise² | ¹UOSD Centro per le Microcitemie - Servizio Emostasi e Trombosi; ²Laboratorio Analisi, Grande Ospedale Metropolitano di Reggio Calabria, Italy

Background and Aims. antiphospholipid antibodies significantly increase the risk of thrombotic events, often necessitating prolonged anticoagulation. Although vitamin K antagonists (VKAs) remain the standard of care, their long‑term management in this population continues to raise questions regarding safety and therapeutic stability. This study evaluated the course of VKA therapy in patients followed at the Hemostasis and Thrombosis Service of Reggio Calabria, with particular attention to hemorrhagic and thrombotic complications.
Methods. we retrospectively analyzed 67 patients (29 males, 38 females; mean age 58.1 years, range 29–87) receiving VKA therapy (Warfarin n=66, Acenocoumarol n=1). All were treated due to antiphospholipid antibody positivity and associated clinical conditions: 50 had venous thrombosis, 15 arterial thrombosis, and 2 were treated for non‑thrombotic disorders. Twenty‑seven patients had concomitant autoimmune diseases, and eight had genetic thrombophilia (4 were heterozygous for the prothrombin G20210A mutation and 4 were heterozygous for Factor V Leiden). Clinical characteristics are summarized in Table 1. The mean follow‑up duration was 2,744.9 days (range 155–10,882). The mean Time in Therapeutic Range (TTR) during the last six months was 68% (range 27–100%).
Results. a total of 10 complications occurred in 9 of 67 patients (13.4%): 3 thrombotic events (4.5%) (1 superficial and 2 deep vein thrombosis) and 7 hemorrhagic events (10.4%) (2 nosebleeds, 2 metrorrhagias, 1 muscle hematoma, and 1 hemoperitoneum). One patient experienced both event types. The annual incidence rate was 2 complications per 100 patient‑years. All events resolved without permanent sequelae; only one case (hemoperitoneum) required hospitalization. Temporary discontinuation of VKA therapy occurred in 7 of 10 events. No fatal outcomes were recorded.
Conclusions. the low annual complication rate, together with a mean TTR exceeding 66%, underscores the safety and effectiveness of VKA therapy when managed by specialized anticoagulation centers. Until direct oral anticoagulants with proven efficacy and safety in antiphospholipid‑positive patients become available, VKAs remain a reliable and well‑established option for the treatment and prevention of thromboembolism. We also observed that venous thrombosis was more than three times as frequent as arterial thrombosis, supporting routine screening for antiphospholipid antibodies in patients with otherwise unexplained venous thrombotic events.