Eosinophilic myocarditis associated with dense deposits of eosinophil cationic protein (ECP) in endomyocardium with high serum ECP

A case of eosinophilic myocarditis following high serum levels of eosinophil cationic protein (ECP) is described. A 27 year old woman was admitted with New York Heart Association (NYHA) class III congestive heart failure. A haematological study showed hypereosinophilia with degranulation and vacuoles; the total eosinophil count was 7980/ml and the ECP serum concentration was noticeably high at 150 ng/ml. Endomyocardial biopsy from the right ventricle showed infiltration of eosinophils and dense deposits of ECP in the endocardium as well as the myocardium. Steroid treatment returned the total eosinophil count and serum ECP to normal, with satisfactory improvement in clinical features. Eosinophilia may cause cardiac damage, and this report confirms that eosinophil degranulation is toxic. Thus, serum ECP seems to be a reliable indicator for diagnosis and for determining treatment parameters of eosinophilic myocarditis.