IJCS | Volume 31, Nº2, March / April 2018

182 Figure 4 – Illustrative example of patients with CCC, presenting Sustained Ventricular Tachycardia (SVT, documented on the ECG of image B) and presenting uptake defect in the inferior and posterolateral walls in the 123-I MIBG SPECT images (image C). Sestamibi Myocardial perfusion images (SMPI) were normal, with myocardial viability in denervated myocardial segments that correlate topographically with the site of origin of SVT. Reprinted from Gadioli, LP et al. Journal of Nuclear Cardiology March 23, 2016 (doi:10.1007/s12350-016-0556-6). and inferior walls and of the apical region. 61 The results of these studies suggest that the extension/severity of the regional myocardial denervation and the intensity of the global derangement of sympathetic innervation (detected in planar images) correlate with the severity of LV systolic dysfunction. 61 A more recent study has shown that cardiac patients with preserved or slightly reduced systolic function and sustained ventricular tachycardia (SVT) presented greater extension of sympathetic denervation evaluated by 123I-MIBG myocardial scintigraphy, compared to individuals without SVT, which reinforces the idea that autonomic cardiac denervation can play an important role in the arrhythmogenesis of this myocardial disease - Figure 4. 39 Magnetic Resonance Imaging: MRI is a methodology which allows analysis ofmorpho-functional parameters of the heart with high degree of two-dimensional detailing, and can be quite elucidative, especially in cases where the quality of the echocardiographic images is poor, or when there are ventricular cavities with advanced geometric changes, making it difficult to performechocardiographic measurement with the usual techniques. It is a method with great capacity for quantitative analysis of ventricular volumes andaccurate calculationof LVejection fraction. 62-66 It can also be quite useful for specific analysis of the right ventricular cavity, according to recent studies. 67 More recent studies call attention for the potential of MRI for detecting the regions of myocardial fibrosis in patients with CCC and for being a potentially valuable non‑invasive risk prediction tool to assess sudden death risk in these patients, even in those with preserved left ventricular ejection fraction. 38 The fibrosis pattern is varied, with the presence of focal or diffusely distributed fibrosis, and evenwith transmural impairment, simulating a fibrosis area usually seen in myocardial infarction due to obstructive coronary disease (Figure 5). Electrophysiological study (EPS): The general indications for EPS apply for patients with CCC. The EPS is required for the evaluation of the sinus node function and AV conduction when the origin of symptoms, particularly syncope, remains uncertain after noninvasive evaluation. In most patients with preserved left ventricular function who have nonsustained ventricular tachycardia or without spontaneous arrhythmia, the EPS does not provide any relevant additional prognostic information. The use of EPS has been proposed in survivors of sudden cardiac death and those with SVT for prognostic evaluation and indication of drug therapy and implantation of antiarrhythmic devices, but the data on the efficacy of this approach are still limited. 68-70 Cardiac catheterization: CCC can mimic several clinical aspects of ischemic heart disease. In fact, patients withCCCmay showprecordial pain, electrocardiographic changes of the ST-T segment and pathological Q waves, Simões et. al. Chagas Disease Cardiomyopathy Int J Cardiovasc Sci. 2018;31(2)173-189 Review Article