Peripheral macrovascular thrombosis in catastrophic antiphospholipid syndrome (CAPS): A descriptive analysis from the "CAPS Registry".

OBJECTIVES: To characterize peripheral macrovascular thrombosis in patients with catastrophic antiphospholipid syndrome (CAPS) and to analyse clinical and laboratory differences between episodes with and without peripheral macrovascular thrombosis, and between arterial and venous events. METHODS: A retrospective cross-sectional study was performed using data from the international "CAPS Registry", including 843 patients. Episodes were classified according to the presence or absence of peripheral macrovascular thrombosis. Vascular characteristics were assessed in episodes with peripheral macrovascular thrombosis, while clinical manifestations, immunological profile, treatment, and mortality were compared across study groups. Univariate and multivariable analyses were performed. RESULTS: Peripheral macrovascular thrombosis occurred in 280 patients (33.2%). Events were mainly venous (58.3%), followed by arterial (30.6%) and combined arterial-venous thrombosis (11.2%). Both venous and arterial thromboses predominantly involved the lower limbs and proximal segments. Male sex, CAPS as the first manifestation of antiphospholipid syndrome, infection and malignancy as triggers, and pulmonary involvement were significantly more frequent in episodes with peripheral macrovascular thrombosis, whereas mortality did not differ significantly between groups. Episodes without peripheral macrovascular thrombosis showed higher rates of systemic lupus erythematosus, triple antiphospholipid antibody positivity, laboratory features of thrombotic microangiopathy, and multiorgan involvement. Arterial thrombosis was associated with older age, and carried high risk of major amputation, with 28 major amputations reported, accounting for 24% of episodes with peripheral arterial thrombosis. CONCLUSION: Peripheral macrovascular thrombosis is a clinically relevant manifestation of CAPS, mainly presenting as deep vein thrombosis. Peripheral arterial thrombosis carried an elevated risk of major amputation, contributing substantially to long-term morbidity.