The Silent Surprise

Introduction Eosinophilic granulomatosis with polyangiitis (EGPA) is an eosinophil-rich small-vessel vasculitis that typically manifests with sinopulmonary disease, with a subset of patients presenting with other manifestations, e.g., neuropathy, glomerulonephritis, and/or cardiac involvement. This Clinical Grand Round will describe a case of EGPA with late cardiac involvement 26 years after the initial diagnosis of EGPA. Discussion Mrs. U, a 75-year-old ethnically European female, presented with syncope on the background of well-controlled anti-neutrophil cytoplasmic antibodies-negative EGPA on long-term maintenance therapy with mycophenolate. Her initial presentation in 1998 (26 years prior) was with eosinophilia and asthma with sinopulmonary involvement. Her last clinical flare was in 2022 (2 years prior) with constitutional symptoms and eosinophilia. As part of her syncope investigation, she was noted to have eosinophilia (1.4 × 109/L) and C-reactive protein (23 mg/L). Troponin T (23 ng/L) and elevated B-type natriuretic peptide (BNP) (2,398 ng/L). Further work up with cardiac MRI demonstrated subacute thrombus at distal left ventricle (LV) and right ventricle (RV), LV myocardial scar (by late gadolinium enhancement), and oedema at distal LV and apex. Her eosinophil cationic protein (ECP) was significantly elevated at >200 ug/L (0–13.3). Given the cardiac imaging finding and relevant clinical history/investigations, we managed her as EGPA with late-onset cardiac involvement. She was treated with combination therapy with corticosteroid, rituximab, and warfarin. Mepolizumab (IL-5 blocker) and benralizumab (IL-5 receptor alpha blocker) were considered; however, she did not qualify for them under the PBS scheme. Mrs. U made continued improvement with the combination therapy, with normalization of her eosinophil count, inflammatory markers, troponin, BNP, and eosinophil cationic protein level. This Clinical Grand Round will outline the management strategy of this late-onset cardiac involvement with EGPA. It will also review the current relevant literature on presentation, diagnosis (serology, imaging, biopsy, and ancillary tests), management, and ongoing research in this field.