ABC | Volume 112, Nº5, May 2019

Original Article Gonzaga et al Cardiac autonomic modulation in breast cancer Arq Bras Cardiol. 2019; 112(5):555-563 Results Table 1 presents the sociodemographic and clinical characteristics of the postmenopausal women without breast cancer and breast cancer survivors who participated in the study. There were no significant differences between groups (p > 0.05). The losses of the sample composition can be visualized in Figure 1. Approximately 70.8% of women who survived breast cancer and 25% of the non-cancer group attended high school. Regarding marital status, 70.8% of women who survived and 60.1% without the disease are married. Of the women analyzed, 41.7% of the survivors of the disease and 55.6% of those without the disease worked from the home, while, 62.4% and 72.8%, respectively, reported having up to two diseases. Regarding the body composition variables analyzed (total body mass, BMI, total lean and fat mass, trunk fat mass, bone mineral density, and bone mineral content), there were no statistically significant differences between the groups. In women with breast cancer, it was observed that 52% had undergone mastectomy surgery and 67% received treatment with chemotherapy. Most women have diagnosed in breast cancer stage I and the mean time of AI use was 19.3 months. The Mean RR, SDNN, RMSSD, NN50, pNN50, RRtri, SD1, and SD2 indices demonstrated statistically significant reductions (Table 2) (p ≤ 0.05) in the breast cancer group when compared to the group without the disease. The Mean HR index (1/me), which represents the heart rate (HR), was lower in the group without the disease. For the TINN index, no significant differences were found between groups (p = 0.216). In the qualitative analysis of the Poincaré plot, there was a lower dispersion of the RR intervals in the cancer group compared to the non-disease group (Figure 2). The indices in the frequency domain of HRV are presented in table 3. For the VLF (ms²), LF (ms 2 ), and HF (ms 2 ) indices, statistically significant reductions (p ≤ 0.05) were found in the breast cancer group when compared to the group without the disease, whereas the LF/HF ratio did not present significant differences between the groups (p = 0.747). Table 1 – Sociodemographic and clinical characteristics of postmenopausal women without breast cancer and breast cancer survivors who participated in the study Variables Group with Breast Cancer (n = 14) Group without Breast Cancer (n = 27) p value Age a 62.17 ± 5.79 60.03 ± 7.57 0.23 Education Illiterate b 8.3% 12.4% First level completed b 16.7% 37.6% 0.63 Second level Completed b 70.8% 25% Superior b 4.2% 25% Marital status Single b 4.2% 11.1% Married b 70.8% 61.1% 0.49 Divorced b 16.7% 5.6% Widow b 8.3% 22.2% Occupation From home b 41.7% 55.6% Work b 41.7% 5.6% 0.25 Retired b 16.6% 38.8% Self-Reported diseases Up to 2 diseases b 62.4% 72.8% 0.49 More than 2 diseases b 16.6% 27.8% Total body mass (kg) a 70.62 ± 12.29 69.67 ± 12.99 0.61 BMI a 30.71 ± 6.03 30.19 ± 4.57 0.59 Total lean mass (kg) a 34.94 ± 4.39 35.53 ± 4.76 0.19 Total fat mass (kg) a 33.38 ± 9.53 31.83 ± 9.54 0.36 Fat mass of thoracic (kg) a 18.17 ± 4.84 16.70 ± 4.75 0.24 BMD a 1.11 ± 0.11 1.17 ± 0.12 0.09 BMC a 2.12 ± 0.32 2.31 ± 0.32 0.11 Student t test a : Mean ± standard deviation; Qui Square test b : categorical variables, percentage. BMI: body mass index; BMD: bone mineral density; BMC: bone mineral content. 558