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Most patients with chronic Chagas' heart disease complain of chest pain. The pathophysiology of this symptom is unknown, although myocardial necrosis and fibrosis are frequent necropsy findings and cardiac autonomic impairment is a prominent feature of the disease. To evaluate the possibility of an ischemic cause for these abnormalities in 23 patients (18 men, aged 32 to 60 years, mean 42) with chronic Chagas' disease complaining of chest pain, thallium-201 myocardial scintigraphy was performed after maximal effort and 4-hour redistribution. Regional wall motion was assessed by radionuclide and contrast angiography. Heart rate responses to sinus respiratory arrhythmia, atropine, phenylephrine and Valsalva maneuver were evaluated in all patients and in 22 normal control subjects. Coronary angiography was performed in 16 patients. Only 1 patient had chest pain and no ischemic electrocardiographic changes occurred in any case during the effort test. Scintigraphic analysis of 7 segments per patient showed perfusion defects in at least 1 segment in all patients. Of 161 myocardial segments 16 showed fixed, 10 reversible, and 22 paradox defects (reverse redistribution). The majority (75%) of the fixed perfusion defects occurred in dyssynergic regions, whereas reverse redistribution predominated in regions with normal wall motion (82%). The reversible defects were present in normal or mildly hypokinetic regions. Markedly impaired parasympathetic cardiac control was present but no significant coronary abnormalities were seen in any of the 16 patients undergoing angiography. It is concluded that whereas fixed defects are likely to correspond to fibrotic or necrotic lesions, reversible and paradox perfusion defects may be caused by regional flow or metabolism derangements, possibly related to abnormal parasympathetic control of the coronary microcirculation.

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Radionuclide angiography was used to study biventricular function in 11 noncardiac (group 1) and eight chronic cardiac chagasic patients (group 2). Results in chagasic patients were compared to those obtained in 10 normal subjects. Global ejection fraction and the standard deviation of peak (SDP) phase histogram were determined for each ventricle and qualitative evaluation of regional wall motion in both anterior and left anterior oblique projections was performed. Left ventricular dysfunction was markedly predominant in group 2, mean +/- SD ejection fraction 39.7 +/- 13.1% and SDP 29.8 +/- 15.6 degrees, as compared to group 1, in which these values were 56.7 +/- 9.9% (P less than 0.01) and 18.3 +/- 7.1 degrees (P less than 0.05), respectively. In contrast, severe right ventricular impairment was found equally in both groups: ejection fraction averaged 31.8 +/- 12.7 and 31.0 +/- 9.1%, and the mean SDP was 29.3 +/- 8.6 and 23.7 +/- 6.7 degrees, in groups 2 and 1, respectively. The qualitative analysis of segmental wall motion also showed apical and/or free-wall right dysynergy in all patients of group 1, while the same abnormalities were detected in six out of eight patients in group 2. These findings indicate that severe functional impairment of right ventricular performance is by far the most significant abnormality detected by radionuclide angiography in chagasic patients who are asymptomatic and have no other clinical sign of heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

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