A female patient is described in whom the diagnosis of
idiopathic hypereosinophilic syndrome (HES) with
heart disease and
peripheral neuropathy was made at the age of 32 years. Although
prednisone induced a prompt and longstanding complete hematological remission, progressive and eventually intractable
heart failure developed, and the patient died 6 years later. Endomyocardial biopsy at diagnosis showed infiltration with intact and disintegrated eosinophils and Charcot-Leyden crystals. Echocardiographic follow-up (including Doppler-Echocardiography) revealed
mitral regurgitation with thickening and impaired motility of the posterior mitral leaflet, as well as progressive
dilated cardiomyopathy. At autopsy, a diffuse interstitial
fibrosis with patchy prominence in an eccentric hypertrophic and highly dilated heart was found. There were no significant endocardial thickening and no mural thrombi. In contrast to the findings of the initial endomyocardial biopsy, autopsy revealed no eosinophilic infiltrate. In this case, eosinophil-induced
heart disease manifested as
dilated cardiomyopathy, without endocardial
fibrosis as originally described by Löffler. We speculate, that eosinophils have been deposited predominantly in the myocard at an early stage of disease, and - activated locally - secreted their granule
proteins producing an initial damage to capillary endothelial cells and myocytes. After
prednisone-induced clearance of eosinophils from blood and tissues, progressive, self-perpetuating interstitial
fibrosis of the myocard and loss of myocytes eventually resulted in end-stage
dilated cardiomyopathy.