ABSTRACT NUMBER: ESOC2026A1614 ISCHAEMIC STROKES, MOYA MOYA ANGIOPATHY, DILATED CARDIOMYOPATHY AND GRAVES’ DISEASE – A RARE ASSOCIATION

Abstract Background and aims We describe a known association between Moya Moya Disease( MMD), autoimmune thyroid disease ( Graves) and dilated cardiomyopathy (DCM). This constellation points toward a shared pathogenic mechanism rather than coincidental coexistence. MMD, DCM, and autoimmune thyroid disease intersect through a genetically primed, immune-mediated vasculopathy, with RNF213 acting as a central susceptibility gene and thyrotoxicosis serving as a disease accelerator. Methods A 45-year-old Caucasian lady with MMD, Graves and DCM presented with repeated ischaemic strokes in both cerebral hemispheres with left sided weakness and cognitive issues. Diagnosis was confirmed with CTA, MRI, Thyroid and antibody profiles and cardiac imaging. She was treated intensively with control of thyroid function, ß-Blockers, MDT care (cardiac, stroke and endocrinology referrals) with some improvement. Results CTA showed changes of obliterative angiopathy with a Moyamoya pattern of collateralisation of wispy vessels. Thyroid peroxidase antibodies were extremely high in titre. Mutation of RNF213 gene is critical in angiogenesis, endothelial integrity, and smooth muscle proliferation and systemic vasculopathy. Graves’ amplifies vascular injury through immune-mediated endothelial dysfunction, and cross-reactivity of TSH-receptor antibodies with vascular tissues. Thyrotoxicosis exacerbates haemodynamic stress by increasing cerebral metabolic demand and myocardial workload. DCM may arise through tachycardia-mediated myocardial dysfunction, direct thyroid toxicity, autoimmune myocarditis, and microvascular impairment in genetically susceptible individuals. This condition represents a high-risk clinical phenotype, with increased vulnerability to stroke and cardiac decompensation during thyrotoxic states. Conclusions Early recognition, aggressive control of thyroid function, cardiac surveillance, and multidisciplinary management are essential. Understanding shared genetic/ immune mechanisms may inform targeted therapies and risk stratification. Conflict of interest Sharvari Inamdar: nothing to disclose, Kamya Rangarajan :nothing to disclose, Swarnika Kichloo: nothing to disclose, Rekha Rao :nothing to disclose, Abdulla Adil Kolakadden: nothing to disclose, Dr Kamal Chokkalingam :nothing to disclose, Dr Senthil Raghunathan :nothing to disclose, Dr Ashit Shetty: nothing to disclose, Dr Sunil K Munshi :nothing to disclose, Zahra Mohamed: nothing to disclose