Abstract
The aim of this study was to explore cardiac autonomic changes assessed by linear and nonlinear indexes of heart rate variability (HRV) and body composition modifications in breast cancer survivors and cancer-free control women. Women who were breast cancer survivors (BCS, n = 27) and without cancer with similar characteristics (Control, n = 31) were recruited for this study. We calculated some relevant linear and nonlinear parameters of 5 min of RR interval time series such as mean RR interval (RRave), the corrected Poincaré index (cSD1/SD2), the sample entropy (SampEn), the long-term fractal scaling exponent (α2) and 2UV from symbolic dynamics. Additionally, we indirectly assessed body composition measures such as body weight, fat mass, visceral fat rating (VFR), normalized VRF (nVFR), muscle mass, metabolic age, and total body water. We found that diverse HRV indexes and only one body composition measure showed statistical differences (p < 0.05) between the BCS and Control groups. RRave: 729 (648–802) vs. 795 (713–852) ms; cSD2/SD1: 3.4 (2.7–5.0) vs. 2.9 (2.3–3.5); SampEn: 1.5 (1.3–1.8) vs. 1.7 (1.5–1.8); α2: 0.6 (0.3–0.6) vs. 0.5 (0.4–0.5); 2UV: 7.1 (4.3–11.5) vs. 10.8 (6.4–15.7) and nVFR 0.12 (0.11–0.13) vs. 0.10 (0.08–0.12) points/kg, respectively. The nVFR was strongly significantly correlated with several indexes of HRV only in the BCS group.Our findings suggest that BCS exhibit lower parasympathetic cardiac activity and changes in HRV patterns compared to Controls. A concomitant increase of visceral fat, among other factors, may contribute to cardiac autonomic disturbances and changes in HRV patterns in BCS.
Highlights
Breast cancer is among the five most common forms of cancer, and it is one of the most important causes of death worldwide, accounting for an estimated 627,000 deaths in 2 0181
Taking into account that metabolic modifications are present in breast cancer survivors (BCS), body composition seems to be a factor of interest in breast cancer management, at the tissue level witch refers to amounts and distributions of adipose, skeletal, and muscle tissue in the patients[8,9]
The heart rate variability (HRV) analysis has been established as a complementary non-invasive and economical tool for the early diagnosis and better prognosis of autonomic cardiac dysfunction and survival in BCS women[19]
Summary
Breast cancer is among the five most common forms of cancer, and it is one of the most important causes of death worldwide, accounting for an estimated 627,000 deaths in 2 0181. In Latin America, breast cancer ranks as the first cancer type among women regarding new cases and deaths[2] These statistics become more relevant in public health since breast cancer can lead to associated diseases and alterations both in early stages and even years after treatment and recuperation. Linear HRV analysis techniques are often insufficient to characterize the complex dynamics of the heartbeat generation since the mechanisms involved in cardiovascular regulation probably interact with each other in a nonlinear w ay[21] With this consideration, promising nonlinear tools such as symbolic dynamics and fractal indexes have been introduced to describe the complexity of HRV. As far as we know, no other studies have compared autonomic cardiac activity assessed by linear and nonlinear HRV measures in conjunction with various measures of body composition values between BCS and cancer-free women. We hypothesized that women who are BCS manifest cardiac autonomic disturbances characterized by a diminished vagal tone related to changes in body composition
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