Abstract
We report a rare case of idiopathic hypereosinophilic syndrome (iHES) associated with extensive multivessel coronary artery ectasia (CAE), a vascular complication seldom described in this condition. A 56-year-old man with known iHES presented with progressive exertional chest pain. Coronary angiography revealed diffuse ectasia of all major epicardial coronary arteries, with a critical stenosis in the mid-right coronary artery. Secondary causes of eosinophilia were excluded, and no clinical or serological evidence of vasculitis or connective tissue disease was found. The patient was treated with corticosteroids, immunosuppressants, and dual antiplatelet therapy, with a favorable outcome. This case illustrates the potential for eosinophil-mediated vascular injury in iHES and emphasizes the need for comprehensive cardiovascular assessment in patients with persistent hypereosinophilia, even in the absence of systemic symptoms. Increased awareness of this underrecognized manifestation may help guide timely diagnosis and management.