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CLINICAL STUDIES

Limited myocardial contractile reserve and chronotropic incompetence in patients with chronic Chagas’ disease

Assessment by dobutamine stress echocardiography

^a Centro de Investigaciones J.F. Torrealba, Hospital Universitario de Caracas, Centro Médico de Caracas, Caracas, Venezuela
^b Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri, USA

Manuscript received February 19, 1998; revised manuscript received August 31, 1998, accepted October 2, 1998.

Reprint requests and correspondence: Julio E. Pérez, MD, Director of Echocardiography, Washington University School of Medicine, 660 S Euclid Avenue, Box 8086, St. Louis, MO 63110-1093

Objectives

To determine whether dobutamine stimulation in patients with Chagas’ disease may uncover abnormal contractile responses as seen in ischemic myocardium.

Background

Segmental left ventricular (LV) dysfunction in the absence of coronary atherosclerosis is frequently seen in patients with chronic Chagas’ heart disease. Myocardial ischemia and coronary microcirculation abnormalities have been found in animal models and in humans with Chagas’ disease. In addition, chagasic sera may contain autoantibodies against human beta-adrenergic receptors.

Methods

Two groups of patients with Chagas’ disease were studied by echocardiography: group 1 (n = 12) without and group 2 (n = 14) with LV segmental wall motion abnormalities (mostly apical aneurysm). Ten normal subjects served as control subjects. We performed qualitative assessment of wall motion and quantitative evaluation of LV cavity under baseline conditions and after dobutamine stimulation.

Results

Patients with Chagas’ disease exhibited a blunted inotropic and chronotropic response to dobutamine stimulation. After dobutamine, fractional area change in Chagas’ group 1 (54.7 ± 6.6%; SD) and in group 2 (35.1 ± 12.1%) were significantly lower than control group (66.7 ± 2.5%; p < 0.001). In addition, in 6 of 14 group 2 patients, dobutamine induced a biphasic response with improvement at low dose and deterioration at peak dose, as seen in patients with coronary artery disease. Although the three groups had similar basal mean heart rates and attained a similar mean peak dobutamine doses, both groups of patients with Chagas’ disease had a significantly blunted mean heart rate effect after dobutamine (p < 0.0001).

Conclusions

Thus, dobutamine stimulation unmasks a chronotropic incompetence and a blunted myocardial contractile response in chagasic patients, even in those with no overt manifestation of heart disease.

Abbreviations and Acronyms   ECG = electrocardiogram or electrocardiographic   EDA = end-diastolic left ventricular cavity area   ESA = end-systolic left ventricular cavity area   HR = heart rate   LV = left ventricle or left ventricular

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				H. Acquatella Echocardiography in Chagas Heart Disease Circulation, March 6, 2007; 115(9): 1124 - 1131. [Abstract] [Full Text] [PDF]