ABSTRACT
Idiopathic hypereosinophilic syndrome is a rare systemic, leukoproliferative disorder characterized by eosinophil- mediated tissue injury causing multiple organ failure, including the heart. Cardiac involvement occurs in more than 75% of patients with hypereosinophilic syndrome. Cardiac manifestations include subendocardial fibrosis, thrombus leading to peripheral emboli, restrictive cardiomyopathy, and valvular dysfunction. It is more common in men than in women (9:1), and trends to present between the ages of 20 and 50 years. Presentation in childhood is unusual. We report for the first time a case of a 58-year-old man with idiopathic hypereosinophilic syndrome manifested by prosthetic aortic valve dysfunction that was successfully treated by steroid and hydroxyurea therapy after surgical valvular replacement.