MYOCARDIAL UPTAKE OF ANTIMYOSIN ANTIBODY IN IDIOPATHIC DILATED CARDIOMYOPATHY AND ITS RELATION TO FUNCTIONAL AND MORPHOLOGICAL PARAMETERS

Monoclonal In-111 antimyosin (AMS) uptake indicates the presence of on going myocyte damage. In idiopathic dilated cardiomyopathy (IDC), ther e is diffuse myocyte damage. We have attempted to find a correlation b etween AMS uptake and functional myocardial parameters. With this purp ose in mind, we studied two groups of subjects: group 1 comprised 19 s ubjects with IDC and group 2 comprised 6 control subjects. In all subj ects, an antimyosin scan was performed. Among the subjects with IDC, t wo-dimensional echocardiography was carried out to determine the left ventricular ejection fraction (LVEF) and left ventricular dimensions, and a gated blood pool study was undertaken to assess the LVEF at rest and end-diastolic and end-systolic volumes. Three months later, repea t antimyosin scintigraphy and equilibrium gated blood pool were perfor med on 13 of the patients. The mean heart to lung (H/L) ratio in the I DC subjects was 1.82 +/- 0.25 (range 1.42-2.25), a value significantly higher than that obtained in the controls: 1.41 +/- 0.12 (range 1.26- 1.58) (P<0.001). Linear regression analysis did not find a statistical ly significant correlation between H/L and gated blood pool or echocar diography measures. No marked changes in ejection fraction and antimyo sin uptake were found between baseline and follow up studies. Subjects with IDC have a high incidence of positive antimyosin scans, but anti myosin uptake is not related to any functional or morphological parame ters.