[Differential diagnosis of idiopathic congestive cardiomyopathy and ischemic heart disease by echocardiography and 201Tl-myocardial scintigraphy (author's transl)].

This study was made to evaluate the usefulness of various non-invasive methods such as electrocardiography, echocardiography and 201T1 myocardial scintigraphy in the differential diagnosis of idiopathic congestive cardiomyopathy (CCM) and ischemic heart disease (IHD). Eighteen cases with CCM and 9 cases with IHD were subjected. For this study patients with IHD showing dilated cavity (LVDd over 66 mm) and diffuse hypokinesis of the left ventricle in the echocardiogram were selected. For echocardiographic study, cross-sectional sector-scan instrument, Toshiba SSH-11A was used, and 201T1 myocardial scintigraphy was performed using Toshiba jumbo gamma camera GCA-401. Cardiothoracic ratio of CCM and IHD were 59.6 +/- 6.3% and 58.3 +/- 6.3% in average, respectively. In CCM, mean LVDd was 76.0 +/- 5.6 mm and mean LVDs was 63.4 +/- 7.3 mm. In IHD, mean LVDd was 74.7 +/- 8.1 mm and mean LVDs as 63.2 +/- 4.6 mm. Both cardiothoracic ratios and echocardiographic findings showed no difference between CCM and IHD. Incidence of an abnormal Q wave in ECG was higher in IHD (2.72 leads per a case) than that in CCM (1.33 leads per a case). An abnormal Q wave in aVL was frequently (28%) observed in CCM but none in IHD. However, these ECG findings did not seem to be contributory to the differential diagnosis. Myocardial scintigraphic study revealed that 10 of 18 cases with CCM showed no perfusion defect or sparse uptake and others showed small and isolated defect in the apex or postero-lateral wall of the left ventricle, while 7 of 9 cases with IHD showed large perfusion defect over 15% in the anterior and inferior areas. However, small localized defects less than 14% in the apex were observed in both groups, 5 cases (27.8%) with CCM, and 2 cases (22.2%) with IHD, suggesting limitation of this method for the differential diagnosis.