Sympathetic Dysautonomia in Heart Failure by 123I-MIBG: comparison between Chagasic, non-Chagasic and heart transplant patients

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Abstract
Background: Heart failure (HF) is a severe public health problem because of its high morbidity and mortality and elevated costs, thus requiring better understanding of its course. In its complex and multifactorial pathogenesis, sympathetic hyperactivity plays a relevant role. Considering that sympathetic dysfunction is already present in the initial phases of chronic Chagas cardiomyopathy (CCC) and frequently associated with a worse prognosis, we assumed it could be more severe in CCC than in cardiomyopathies of other etiologies (non-CCC). Objectives: To assess the cardiac sympathetic dysfunction (I-123-MIBG) of HF, comparing individuals with CCC to those with non-CCC, using heart transplant (HT) patients as denervated heart parameters. Methods: We assessed 76 patients with functional class II-VI HF, being 25 CCC (17 men), 25 non-CCC (14 men) and 26 HT (20 men), by use of cardiac I-123-metaiodobenzylguanidine (I-123-MIBG) scintigraphy, estimating the early and late heart-to-mediastinum ratio (HMR) of I-123-MIBG uptake and cardiac washout (WO%). The 5% significance level was adopted in the statistical analysis. Results: The early and late HMR values were 1.73 +/- 0.24 and 1.58 +/- 0.27, respectively, in CCC, and 1.62 +/- 0.21 and 1.44 +/- 0.16 in non-CCC (p = NS), being, however, higher in HT patients (p < 0.001). The WO% values were 41.65 +/- 21.4 (CCC), 47.37 +/- 14.19% (non-CCC) and 43.29 +/- 23.02 (HT), p = 0.057. The late HMR values showed a positive weak correlation with left ventricular ejection fraction (LVEF) in CCC and non-CCC (r = 0.42 and p = 0.045; and r = 0.49 and p = 0.015, respectively). Conclusion: Sympathetic hyperactivity ( I-123-MIBG) was evidenced in patients with class II-IV HF, WEE < 45%, independently of the HF etiology, as compared to HT patients.

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