ABC | Volume 114, Nº4, April 2020

Original Article Souza et al. Nocturnal BP fall in acute Chagas disease Arq Bras Cardiol. 2020; 114(4):711-715 ganglion cells. 11,12 Impairment of the nervous system can be demonstrated in all stages of Chagas disease, and changes in the parasympathetic autonomic nervous system control have not been correlated with cardiovascular symptoms by functional tests on humans. 13 The loss of autonomic control in chronic Chagas disease was described in a case-control study that evaluated the correlation between sympathetic innervation, changes in perfusion and abnormalities in the ventricular wall, showing that cardiac sympathetic dysfunction occurs in early stages of the disease and is associated with the worsening of autonomic dysfunction. 14 However, studies on autonomic function in the acute phase of Chagas disease are scarce. Evidences have shown the involvement of the autonomic nervous system, especially the parasympathetic system, soon after initial infection, i.e., in the undetermined phase of Chagas disease. 15 Physiological variations in BP have a circadian rhythm, with fluctuations over 24 hours and BP drop during sleep. This fall, detected by ABPM, normally exceeds 10% of BP in the awake state, and is observed in approximately 95% of the normotensive individuals. 16 During sleep, there are specific changes in autonomic and endocrine functions, with reduced sympathetic activity and predominance of parasympathetic activity, leading to physiological BP fall. 17,18 The observations in clinical practice indicating that many patients with ACD that underwent ABPM for any reason did not show nocturnal fall of BP motivated the development of a systematic study to analyze the behavior of BP in ABPM. In the control group, we included only individuals with good cardiovascular health, with no history of hypertension, diabetes or cardiovascular disease. All individuals had normal office BP (mean of the last two measures <140/90 mmHg). The only drug taken by the patients with ACD was benznidazole, an antiparasitic medication used in the treatment of T. cruzi infection, the causative agent of Chagas disease. Lack of BP fall during sleep was seen in a large proportion (more than half) of patients with ACD, and nocturnal increase of BP occurred in a significant proportion of patients (12.9% in SBP and 18.5% in DPB). Table 2 – Number of patients with changes in ambulatory blood pressure monitoring (ABPM) in patients with acute Chagas disease and controls Controls Acute Chagas disease Women (n=30) Men (n=24) Total (n=54) Women (n=30) Men (n=24) Total (n=54) Absence of nocturnal fall in SBP 5 4 9 (16.6%) 20 20 40 (74.0%)* Absence of nocturnal fall in DBP 4 3 7 (12.9%) 9 20 29 (53.7%)* Absence of nocturnal fall in SBP and DBP 4 3 7 (12.9%) 16 12 28 (51.8%)* Nocturnal increase in SBP 0 1 1 (1.8%) 5 2 7 (12.9%)* Nocturnal increase in DBP 0 1 1 (1.8%) 5 5 10 (18.5%)* Data expressed as absolute and relative numbers. Chi-square test for comparisons between acute Chagas disease and control groups; p<0.05. The neurohumoral features of the acute phase of Chagas disease are not well known, mainly due to epidemiological characteristics and difficult diagnosis. However, due to changes in the disease profile and the increase in the number of cases of oral contamination, with greater parasite load, we have found more obvious clinical manifestations. 19 This lack of nocturnal fall in BP in the acute phase of Chagas disease may be the result of a disturbance in the autonomic nervous system. One limitation of this study is that we did not perform an analysis of heart rate variability, since our objective was to evaluate BP behavior over 24 hours. Conclusions The results of this study suggest that the ABPM can be a useful tool for early detection of autonomic changes in the acute phase of Chagas disease. Since this was a descriptive study of patients with ACD, it is not possible to understand the real meaning of these changes, since there is no consensus about the reproducibility of this result and clinical outcomes at long term. Author contributions Conception and design of the research and Acquisition of data: Souza DS, Oliveira CB, Maciel BG, Maciel MTS, Póvoa R; Analysis and interpretation of the data: Bianco HT, Póvoa R; Statistical analysis and Writing of the manuscript: Souza DS, Bianco HT, Póvoa R; Critical revision of the manuscript for intellectual content: BiancoHT, Fonseca FAH, Izar MC, Póvoa R. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding There were no external funding sources for this study. Study Association This study is not associatedwith any thesis or dissertationwork 713