Magnetic Resonance Imaging in Chronic Chagas' Disease: Correlation with Endomyocardial Biopsy Findings and Gallium-67 Cardiac Uptake.

Abstract

BACKGROUND: We studied the correlation among cardiac magnetic resonance imaging (MRI), gallium-67 myocardial uptake, and right ventricular endomyocardial biopsy results in chronic Chagas' disease. To our knowledge, this represents the first attempt to correlate the histological findings with cardiac MRI and gallium-67 myocardial uptake for noninvasive diagnosis of inflammatory activity associated with Chagas' disease. METHODS: Ten male patients with cardiomyopathy secondary to Chagas' disease were studied (mean age, 47.7 +/- 7 years; congestive heart failure New York Heart Association [NYHA] functional class II [two patients], III [six patients], and IV [two patients]; and mean echocardiographic left ventricular [LV] ejection fraction [EF], 36 +/- 6%). The patients underwent right ventricular endomyocardial biopsy, cardiac MRI, and gallium-67 myocardial uptake testing. The results of this group were compared with those of a control group of patients with idiopathic dilated cardiomyopathy who were matched in age (mean age, 46 +/- 10 years), LV function (mean echocardiographic EF, 30 +/- 4%), and NYHA classification (one patient in class II, five patients in class III, and one patient in class IV). RESULTS: All patients with Chagas' disease showed higher signal intensity on MRI after the administration of gadolinium. The intensity of the septal signal changed from 0.90 +/- 0.11 to 1.56 +/- 0.19 (P < 0.001). In the control group, there was no difference in signal intensity with gadolinium (mean septal intensity, 0.94 +/- 0.12 before and 0.99 +/- 0.15 after; NS). On biopsy, eight chagasic patients had evident signs of myocarditis, and two patients had borderline evidence myocarditis. However, only one patient in the control group had a histological diagnosis of borderline myocarditis. Gallium-67 cardiac uptake was positive for myocardial inflammatory process in seven chagasic patients and borderline in one. On the other hand, only one patient in the control group had an uptake that was positive for inflammation, and one had a borderline result. CONCLUSIONS: In conclusion, the data from this study strongly suggest that myocarditis is frequently found in Chagas' disease. Cardiac MRI appears to be an accurate and alternative method for the diagnosis of inflammatory process associated with Chagas' disease.