M-mode and two dimensional echocardiography in chronic Chagas' heart disease. A clinical and pathologic study

Abstract

64 patients prospectively identified as having Chagas' disease were studied with M-mode echocardiography to identify characteristic functional and anatomic features of cardiac involvement. The control groups consisted of 10 normal subjects and 16 patients with nonischemic cardiomyopathy not due to Chagas' disease. 17 of the patients with Chagas' disease were asymptomatic and all had normal M-mode echocardiograms. Arrhythmias or congestive heart failure caused symptoms in 47 of the patients with Chagas' disease, 18 of whom had a distinct M-mode pattern characterized by left ventricular posterior wall hypokinesis and relatively preserved septal motion. Eleven of the 47 had diffuse hypokinesis indistinguishable from the nonspecific pattern of congestive cardiomyopathy. These motion patterns were quantitated by computing the ratio of the percentage of septal systolic wall thickening to the percentage of posterior wall thickening from measurements taken at the levels of the chordae and papillary muscles. This ratio (normal 0.45 ± 0.20 [±SD]) separated symptomatic patients with Chagas' disease (arrhythmia 0.83 ± 0.66, congestive heart failure 1.50 ± 1.68) from those in whom congestive cardiomyopathy was not due to Chagas' disease (0.29 ± 0.37) (p = 0.02-0.005). In addition, two-dimensional echocardiograms were obtained in 41 of 64 patients with Chagas' disease. These sector scans identified apical aneurysms and/or dyskinesis in 31 patients. We also found apical abnormalities in three of seven asymptomatic patients with Chagas' disease who had normal ECG and M-mode echocardiograms. Echocardiographic findings were confirmed in 15 patients by cineangiography, in four at autopsy and in two at aneurysmectomy. We conclude that in some patients with chronic Chagas' disease, echocardiography shows a pattern indistinguishable from that of diffuse congestive cardiomyopathy. However, in the majority, echocardiography can detect a characteristic apical abnormality that often involves the postinferior left ventricular wall, with the interventricular septum relatively spared. In asymptomatic patients, two-dimensional echocardiography is of particular value in detecting early changes of the left ventricular apex.