In many cases, the diagnosis of eosinophilic myocarditis is suggested by an elevated peripheral blood eosinophil count. However, no detailed studies have been performed on the sequential changes in the initial peripheral blood eosinophil count over the course of the disease. We measured the peripheral blood eosinophil count at the time of presentation in eight patients with eosinophilic myocarditis proven by endomyocardial biopsy and intermittently thereafter. The eosinophil count at the time of onset was <500/mm(3) in four patients, >500/mm(3) but <1,000/mm(3) in three patients, and > or =1,000/mm(3) in one patient. In three of the four patients with an initial eosinophil count of <500/mm(3), an increase to > or =500/mm(3) occurred 7-12 days after the onset. The remaining patient did not develop peripheral eosinophilia. In conclusion, in the early stage of eosinophilic myocarditis, peripheral hypereosinophilia is not present initially in some patients, and may not develop during the course of the illness in a subset of these patients.

n the acute phase of myocarditis, 1-3 ventricular wall thickening is sometimes observed 4-18 and is believed to be caused by interstitial edema. However, no reports have characterized the wall thickening in a large number of cases and, furthermore, its cause is not yet fully understood. This prompted us to investigate whether ventricular wall thickening in the acute phase of myocarditis is attributable to interstitial edema, by focusing on the echocardiographic changes in left ventricular wall thickness and dimensions, as well as the histologic findings in myocardial biopsy specimens. Methods The study group comprised 25 patients selected out of 55 patients hospitalized and diagnosed with acute myocarditis during the 11-year period from 1987 to 1997 at Fujita Health University or Nagoya Dai-ni Red Cross Hospital. The selected patients were chosen because they were able to undergo echocardiography and endomyocardial biopsy during both the acute and convalescent phases of myocarditis. Lymphocytic myocarditis was present in 17 patients, and eosinophilic myocarditis 19 in 8 patients (Table 1). Lymphocytic myocarditis was characterized by the onset of flu-like symptoms, cardiac failure associated

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In studies of all the layers of autopsied hearts from patients with chronic myocarditis, local clusters of lymphocytes are frequently noted, in contrast with hearts obtained from patients with acute myocarditis. Myocardial biopsy specimens, however are no larger than about 2mm x 3mm. With this in mind, the present study was undertaken to determine whether chronic myocarditis can be diagnosed by endomyocardial biopsy. Specimens were obtained from seven patients in whom chronic myocarditis was confirmed by the clinical course and by autopsy findings. In H&E stained specimens, sites corresponding to the biopsy sites in both ventricles (right ventricular free wall, right ventricular side of the ventricular septum, left ventricular lateral wall) were selected at random (five sites each from the right and left ventricles in each patient) and examined under a light microscope. A mean of 5 or more lymphocytes per visual field (by light microscopy at 400-fold magnification), a proposed quantitative diagnostic criterion of myocarditis, was noted in the right ventricle in three patients (5 lymphocytes in two patients and 6 in one patient) and in the left ventricle in one patient (5 lymphocytes). Also, when the presence of lymphocyte clusters, considered to be a characteristic feature of chronic myocarditis, was determined, clusters of 20 or more lymphocytes per visual field were found in the same patients as those mentioned above, namely, in three patients (42.8%) in the right ventricle, as mentioned above, and in one patient (14.3%) in the left ventricle. At the sites of these lymphocyte clusters. findings such as degenerative changes of the myocardial cells and interstitial fibrosis were also associated, making possible a diagnosis of myocarditis. Therefore, in chronic myocarditis, even if five specimens are obtained by right ventricular biopsy, in approximately one half of patients the diagnosis of chronic myocarditis will be missed because of sampling errors.

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