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.

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Purpose: 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. Methods: Women who were breast cancer survivors (BCS, n=27) and cancer-free control participants with similar characteristics (Control, n=31) were enrolled in the Regional General Hospital No. 251 of the Mexican Institute of Social Security (Metepec, Mexico). We processed five minutes of R-R interval time series, and we calculated relevant linear and nonlinear parameters of HRV such as mean RR interval (RRave), the Root Mean Square of the Successive Differences (RMSSD), the Poincaré plot measures SD1, SD2, SD1/SD2, and the sample entropy (SampEn). 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.Results: 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; RMSSD: 16.5 (8.9–27.0) vs. 19.7 (14.2–28.5) ms; SD1: 11.6 (6.3–19.0) vs. 13.9 (10.0–20.1) ms; SD1/SD2: 2.5 (2.1–3.3) vs. 2.2 (1.9–2.7), SampEn: 1.5 (1.3–1.8) vs. 1.7 (1.5–1.8), and nVFR 0.12 (0.11–0.13) vs.0.10 (0.08–0.12) points/kg, respectively. The nVFR was significantly correlated to several indexes of HRV.Conclusions: BCS exhibit a lower parasympathetic cardiac activity and changes in HRV patterns than controls, likely because of the concomitant increase of visceral fat.