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 Figure 2 – Qualitative analysis of the Poincare plot. SD1 (standard deviation of instantaneous variability), SD2 (standard deviation of the continuous RR intervals). Control: SD1 = 18 ms; SD2 = 45 ms / Breast Cancer: SD1 = 10.9 ms; SD2 = 32.6 ms. 1000 1000 900 900 800 800 700 700 600 600 500 500 1000 1000 900 900 800 800 700 700 600 600 500 500 RRn + 1 (ms) RRn + 1 (ms) RRn + 1 (ms) RRn + 1 (ms) A) CONTROL B) BREAST CANCER Table 2 – Linear indices in time domain of heart rate variability in each group Group with breast cancer (n = 14) Group without breast cancer (n = 27) p value Mean RR ms a 707.76 ± 89.86 867.80 ± 128.87 0.047 SDNN ms a 17.92 ± 5.05 35.20 ± 14.94 0,042 Mean HR 1/mim a 85.89 ± 10.49 70.77 ± 10.75 0,050 RMSSD ms b 11.30 ± 8.40 18.40 ± 16.00 0.010 NN50 count b 0.00 ± 4.00 15.00 ± 90.50 0.022 pNN50 % b 0.00 ± 0,40 1.50 ± 9.05 0.022 RRtri a 5.76 ± 1.58 9.93 ± 4.01 0.015 TINN ms a 86.00 ± 22.19 138.40 ± 79.38 0.243 SD1 ms b 8.00 ± 5.75 13.00 ± 11.35 0.009 SD2 ms a 23.90 ± 6.51 46.91 ± 19.95 0.022 Student t testa: Mean ± standard deviation; Mann Whitney testb: Median ± interquartile range; SDNN: standard deviation of all normal RR intervals; HR: heart rate; RMSSD: square root of the mean of the squared differences between adjacent normal RR interval; NN50: number of pairs of successive NNs that differ by more than 50 ms; pNN50: proportion of NN50 divided by total number of NNs; RRtri: RR triangular; TINN: triangular interpolation of NN interval; SD1: instantaneous variability of beat-to-beat variability, SD2: long-term standard deviation of continuous RR intervals index; ms: milliseconds. Table 4 shows the correlation of HRV indices with the inflammatory marker PCR and table 5 presents the variables blood glucose, triglycerides, and high-density lipoprotein with and without age adjustments in women with breast cancer. There were no statistically significant correlations between the indices and the inflammatory marker, even when adjusted for age (p > 0.05), or between the Mean RR, Mean HR, RMSSD, NN50, pNN50, RR tri, TINN, VLF ms², LF ms², LF/HF, and SD1 for the variables blood glucose, triglycerides, and high density lipoprotein (p > 0.05). When adjusted for age the RR tri, HF ms², and SD2 indices presented inversely proportional correlations with the triglycerides [HF - β 95% CI = -0.53, p = 0.045; SD2 - β 95% CI = -0.13, p = 0.044]; RRtri - β 95% CI = -0.02, p = 0.046]. Discussion The main findings of this study demonstrate that women who are survivors of breast cancer who use AI present reductions in HRV compared to women without cancer and that these HRV indices correlate with the lipid profile. In the present study, a statistically significant reduction in the SDNN and RR tri indices, as well as the RMSSD, SD1, NN50, and HF indices, can be observed in women with breast cancer using AI when compared to the non-cancer group, suggesting a reduction in global and vagal modulation, respectively. Moreover, the visual analysis of the Poincaré plot demonstrates a lower dispersion of the RR intervals in the cancer group, indicating that these women present HRV reduction. 559