ABC | Volume 111, Nº2, August 2018

Original Article Marino et al 123 I-MIBG Scintigraphy in Heart Failure Arq Bras Cardiol. 2018; 111(2):182-190 1. Roger VL. Epidemiology of heart failure. Circ Res. 2013;113(6):646-59. 2. BocchiEA.HeartfailureinSouthAmerica.CurrCardiolRev.2013;9(2):147-56. 3. Freitas HF, Chizzola PR, Paes AT, Lima AC, Mansur AJ. Risk stratification in a Brazilian hospital-based cohort of 1220 outpatients with heart failure: role of Chagas’ heart disease. Int J Cardiol. 2005;102(2):239-47. 4. Bestetti RB, Muccillo G. Clinical course of Chagas’ heart disease: a comparisonwith dilated cardiomyopathy. Int J Cardiol. 1997;60(2):187-93. 5. Vilas Boas LG, Bestetti RB, Otaviano AP, Cardinalli-Neto A, Nogueira PR. Outcome of Chagas cardiomyopathy in comparison to ischemic cardiomyopathy. Int J Cardiol.167(2):486-90. 6. Barbosa AP, Cardinalli Neto A, Otaviano AP, Rocha BF, Bestetti RB. Comparison of outcome between Chagas cardiomyopathy and idiopathic dilated cardiomyopathy. Arq Bras Cardiol. 2011;97(6):517-25. 7. Bristow MR. Why does the myocardium fail? Insights from basic science. Lancet. 1998 Aug;352 Suppl 1:Si8-14. 8. Meredith IT, Eisenhofer G, Lambert GW, Dewar EM, Jennings GL, Esler MD. Cardiac sympathetic nervous activity in congestive heart failure. Evidence for increased neuronal norepinephrine release and preserved neuronal uptake. Circulation. 1993;88(1):136-45. 9. Ungerer M, Bohm M, Elce JS, Erdmann E, Lohse MJ. Altered expression of beta-adrenergic receptor kinase and beta 1-adrenergic receptors in the failing human heart. Circulation. 1993;87(2):454-63. 10. Triposkiadis F, Karayannis G, Giamouzis G, Skoularigis J, Louridas G, Butler J. The sympathetic nervous system in heart failure physiology, pathophysiology, and clinical implications. J Am Coll Cardiol. 2009;54(19):1747-62. References The estimatedWO% values were elevated and abnormal in the three groups studied, being compatible with sympathetic dysfunction in patients with HF and not different from those of HT (p = 0.577). The sympathetic tone, translated by WO%, 13,28 might be altered earlier and more markedly than late HMR, and, thus, could be a more sensitive parameter for prognostic assessment, as described. 33 Finally, a positive, although weak, but statistically significant correlation between HMR and LVEF was observed in individuals with HF. The LVEF is routinely used for the prognostic assessment of HF. 22,36 Thus, that weak correlation can indicate that this scintigraphic parameter is more accurate and earlier altered, as reported by Ogita et al., suggesting it is a better predictor of prognosis than LVEF. 33 In addition, it is worth noting that the correlation of early and late HMR with LVEF in CCC patients identified in this study has not been reported in the literature. Study limitations This is a cross-sectional nonrandomized study of patients with advanced HF (NYHA functional class II-IV), thus its findings cannot be generalized to all individuals with CCC. There are no strictly established reference values to quantify the scintigraphic parameters because different methodologies have been used (decay factor, correction of septal penetration of iodine). 28,29 The maintenance of the medication by the patients (ACEI and beta-blockers) might have led to overestimation of the HMR values and influenced our results, although the number of patients on medications did not differ between the CCC and non-CCC groups, and most studies in the literature have been performed considering the severity of HF. 24,25,33 Conclusion This study evidenced the presence of cardiac sympathetic autonomic dysfunction on myocardial 123 I-MIBG scintigraphy, regardless of the HF etiology, and its magnitude was equal in individuals with CCC and non-CCC as compared toHT patients. Author contributions Conception and design of the research: Marino VSP, Dumont SM, Mota LG, Moreira MCV; Acquisition of data: Marino VSP, Mota LG, Braga DS, Moreira MCV; Analysis and interpretation of the data: Marino VSP, Dumont SM, Moreira MCV; Statistical analysis: Marino VSP, Moreira MCV; Obtaining financing: Moreira MCV; Writing of the manuscript: Marino VSP, Dumont SM, Freitas SS, Moreira MCV; Critical revision of the manuscript for intellectual content: Marino VSP, Dumont SM, Mota LG, Braga DS, Freitas SS, Moreira MCV. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding This study was funded by FAPEMIG. Study Association This article is part of the thesis of Post-Doctoral submitted by Viviane Santuari Parisotto Marino, from Faculdade de Medicina da Universidade Federal de Minas Gerais. Ethics approval and consent to participate This study was approved by the Ethics Committee of the Universidade Federal de Minas Gerais - Comitê de ética em Pesquisa (COEP) under the protocol number ETIC 0116.0.203.000-11. All the procedures in this study were in accordance with the 1975 Helsinki Declaration, updated in 2013. Informed consent was obtained from all participants included in the study. 188