Heart disease characterized by
endomyocardial fibrosis is one of the major causes of morbidity and mortality in the
idiopathic hypereosinophilic syndrome. From our series of 50 patients with idiopathic
hypereosinophilia, we defined the noncardiovascular characteristics that distinguish patients at risk of developing
endomyocardial fibrosis from those who remain free of
heart disease. These groups did not differ with respect to the extent of
eosinophilia or the duration of disease. Patients with clinically overt
heart disease were more likely (p less than 0.05) to be male and HLA-Bw44 positive and have
splenomegaly,
thrombocytopenia, elevated serum levels of
vitamin B12, and hypogranular or vacuolated eosinophils and abnormal early myeloid precursors in the peripheral blood. These idiopathic hypereosinophilic patients with
heart disease were also more likely to have
fibrosis and decreased megakaryocytes in the bone marrow. In contrast, those who remained free of
heart disease tended to be female and have
angioedema,
hypergammaglobulinemia, elevated serum levels of
immunoglobulin E (
IgE), and circulating
immune complexes. Therefore, in the
idiopathic hypereosinophilic syndrome, male patients with a myeloproliferative type disorder and the HLA-Bw44 haplotype were at a much increased risk for the development of
endomyocardial fibrosis. However, those patients with a
hypersensitivity-like illness and
angioedema who were female did not develop
heart disease. Appreciation of this relative degree of risk for the major complication of the
idiopathic hypereosinophilic syndrome should prove useful in the early identification and appropriate treatment of patients in whom
endomyocardial fibrosis might develop.