PO061 | LONG-TERM HEADACHE IMPROVEMENT WITH VITAMIN K ANTAGONISTS IN PRIMARY AND SECONDARY ANTIPHOSPHOLIPID SYNDROME: 2-YEAR OBSERVATIONAL COHORT

A. Hoxha^1|2, C. Belizna³, E. Esteve-Valverde⁴, A. Prundean⁵, A. Godon⁶, G. Gobbo^1|2, A. Anunciación-Llunell^7|8|9, R. Ferrer-Oliveras¹⁰, J.O. Latino¹¹, S. Udry¹¹, J. Alijotas-Reig^7|8|9 | ¹Department of Medicine, University of Padua, Padova, Italy; ²Internal Medicine Unit, Thrombosis and Bleeding Disorder Center, University Hospital of Padua, Padova, Italy; ³Vascular and Coagulation Department, University Hospital Angers, Angers, France; ⁴Systemic Autoimmune Diseases Unit, Department of Internal Medicine, Hospital Sant Camil, Consorci Sanitari del Garraf, Barcelona, Spain; ⁵University of Angers, Inserm, CNRS, MITOVASC, SFR ICAT, Angers, France; ⁶Centre Hospitalier Universitaire Angers, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Centre de Recherche en Cancérologie et Immunologie Intégrée Nantes Angers, Laboratoire d'Hématologie, Université d'Angers, Nantes Université, Angers, France; ⁷Department of Medicine, Universitat Autònoma de Barcelona, Spain; ⁸Systemic Autoimmune Disease Unit, Department of Internal Medicine, Vall d'Hebron University Hospital, Spain; ⁹Systemic Autoimmune Diseases Research Unit, Vall d'Hebron Institut de Recerca, Barcelona, Spain; ¹⁰Obstetrics Department, High-Risk Unit, Hospital Universitario Quirónsalud, Barcelona, Spain; ¹¹Autoimmune, Thrombophilic Diseases and Pregnancy Division, Dr. Carlos G. Durand Hospital, Buenos Aires, Argentina

Background and aims. Headache is a frequent and often disabling manifestation in patients with antiphospholipid syndrome (APS) and in individuals positive for antiphospholipid antibodies (aPL). While previous reports have suggested a potential benefit of anticoagulation on headache symptoms, available evidence remains limited, heterogeneous, and largely retrospective. This study aimed to evaluate the long-term effect of vitamin K antagonists (VKA) on headache outcomes in a well-characterized APS cohort over a 24-month follow-up.
Methods. We conducted a prospective observational cohort study including 26 patients fulfilling ACR/EULAR classification criteria for APS, all presenting with chronic or recurrent headache prior to anticoagulation. Patients received long-term warfarin with therapeutic INR targets. The cohort included predominantly thrombotic APS phenotypes (23 venous events, 3 ischemic strokes), with 18 primary APS and 6 APS secondary to systemic lupus erythematosus. No additional headache-specific treatments were introduced during follow-up. Headache severity and impact were systematically assessed at baseline, 12, and 24 months using validated tools (Numeric Rating Scale [NRS], HIT-6, and MIDAS). Outcomes were categorized as complete resolution, major improvement (≥50% reduction in pain), or no improvement.
Results. At 12 months, complete headache resolution was observed in 8 (30.8%) patients. This proportion increased to 13 patients (50%) at 24 months, with an additional 10 patients (38%) experiencing major improvement. Overall, 88% of patients demonstrated clinically meaningful benefit after two years of VKA therapy. Warfarin was well tolerated, with no unexpected safety concerns. Sustained improvement was observed across both primary and secondary APS subgroups.
Conclusions. This study provides the first longitudinal evidence supporting a significant and sustained improvement of headache symptoms in APS patients treated with vitamin K antagonists. The findings reinforce the hypothesis of a pathogenic link between aPL-related mechanisms and headache, and highlight anticoagulation as a potential therapeutic strategy in selected patients. These results warrant confirmation in controlled prospective trials to better define indications and optimize management strategies.