Detection of myocarditis during the first year after discovery of a dilated cardiomyopathy by endomyocardial biopsy and gallium-67 myocardial scintigraphy: prospective multicentre French study of 91 patients.

The purpose of this study was to assess the frequency of inflammatory lesions in the myocardium of subjects with dilated cardiomyopathy and to determine if there was any correlation between the results of two methods of evaluation, one (endomyocardial biopsy) invasive and the other (gallium-67 scintigraphy) noninvasive. Of 115 subjects recruited in seven centres, 91 met the inclusion criteria (left ventricular dilatation greater than or equal to 100 ml m-2 and ejection fraction less than 55% with normal coronary arteriography) and had endomyocardial biopsy (mean five specimens) and Ga-67 myocardial scintigraphy after several days. Scanning was considered doubtful 19 times and positive 13 times. The histologic count of mononuclear cells in the myocardial interstitium in 20 fields was greater than 5 cells field-1 in only four cases. No correlation was found between the two methods. Subjectivity in the choice of the criterion of positivity of Ga-67 scintigraphy and difficulties in identifying lymphocytes upon pathological examination were the major problems encountered. Despite limitations, both techniques suggest that cellular infiltrates are minimal and quite infrequent in dilated cardiomyopathy.