[Left ventricular mechanics in Chagas' disease and dilated cardiomyopathy: echocardiographic study].

For purposes of studying left ventricular mechanics, 184 chronic chagasic and 85 primary cardiomyopathy patients were submitted to an extensive invasive (LV cine, right and left cardiac catheterization and coronarography) and non-invasive protocol. The afterload, (mean wall stress), the contractile status (ejection fraction and circumpherential shortening) and the degree of hypertrophy (mass index) were assessed by M mode echocardiography. There was a very early increase of afterload in 8% of chagasic patients without evidences of LV myocardial involvement in the left cineventriculogram (group I-A). This increased afterload was accompanied by signs of inadequate hypertrophy in 15% of patients with early segmental myocardial damage (group IB). In contrast, ejection fraction and % circumpherential shortening were depressed only in patients with clinical evidences of congestive heart failure. Dilated primary CM patients showed similar findings, except for a more evident depression of contractility in those cases without signs of congestive heart failure (group II) and more hypertrophy than equivalent group III chagasic patients. Measurements of mean systolic wall stress and mass index are valuable parameters for identification of those patients with early increased after-load and inadequate hypertrophy which could benefit from the administration of oral vasodilators.