Changes in Cardiac Autonomic Modulation in Women with Breast Cancer Using Aromatase Inhibitors and the Relation with Biochemical Variables

Abstract Background: The use of autonomic modulation as a predictor of cardiovascular risk in women with breast cancer is important. Objective: To evaluate the cardiac autonomic modulation of postmenopausal women using aromatase inhibitors for breast cancer treatment, as well as its relation with the following biochemical variables. Methods: Postmenopausal women who did not have breast cancer (n = 33) and postmenopausal women with breast cancer (n = 15). For evaluation of the autonomic modulation the heart rate was recorded beat-to-beat for 30 minutes and the series of RR intervals obtained were used to calculate the following heart rate variability indices: Mean RR ms, SDNN (standard deviation of all normal RR intervals, expressed in milliseconds) ms, Mean HR, RMSSD (square root of the mean of the squared differences between adjacent normal RR interval) ms, NN50 (number of pairs of successive NNs that differ by more than 50 ms) count, pNN50% (proportion of NN50 divided by total number of NNs), RRtri (RR triangular), TINN (triangular interpolation of NN interval) ms, SD1 ms, SD2 ms, LF ms2, HF ms2, LH/HF ms2. The values of biochemical variables (fasting glycemia, triglycerides, HDL-cholesterol, and C-reactive protein) were analyzed by blood sample. Results: Lower values of heart rate variability indices were observed in postmenopausal women with breast cancer in relation to postmenopausal women who did not have breast cancer: Mean RR (p = 0.03); SDNN (p = 0.03); RMSSD (p = 0.03); NN50 count (p = 0.03); pNN50 % (p = 0.03); RRtri (p = 0.02); SD1 (p = 0.01); SD2 (p = 0.02); LF ms2 (p = 0.01); HF ms2 (p = 0.03).There was an inversely proportional correlation between the indices SDNN, SD2, and HFms2 with triglycerides (SDNN p = 0.04; SD2 p = 0.04; HF ms2 p = 0.04). No statistically significant correlations were found between heart rate variability indices and others variables. Statistical significance was set at 5% for all analyses. Conclusion: Women with breast cancer present reduced autonomic modulation and in these women of heart rate variability indices are inversely correlated with triglyceride values.摘要 背景：将自主神经调节作为乳腺癌女性心血管风险预测因子的研究具有重要临床意义。目的：评估接受芳香化酶抑制剂（aromatase inhibitors）治疗乳腺癌的绝经后女性的心脏自主神经调节功能，及其与下述生化指标的关联。方法：纳入无乳腺癌的绝经后女性（n=33）与罹患乳腺癌的绝经后女性（n=15）。为评估自主神经调节功能，以逐搏方式记录心率30分钟，通过获取的RR间期序列计算以下心率变异性指标：平均RR间期（单位：毫秒，ms）、SDNN（所有正常RR间期的标准差，单位：毫秒）、平均心率、RMSSD（相邻正常RR间期差值均方的平方根，单位：毫秒）、NN50计数（连续正常RR间期差值超过50ms的配对数目）、pNN50%（NN50计数占总正常RR间期数的比例）、RR三角指数（RRtri）、TINN（RR间期的三角插值值，单位：毫秒）、SD1（单位：毫秒）、SD2（单位：毫秒）、低频功率（LF，单位：ms²）、高频功率（HF，单位：ms²）、LF/HF（单位：ms²）。通过血液样本检测生化指标：空腹血糖、甘油三酯、高密度脂蛋白胆固醇（HDL-cholesterol）与C反应蛋白（C-reactive protein）。结果：与无乳腺癌的绝经后女性相比，罹患乳腺癌的绝经后女性的心率变异性指标显著降低：平均RR间期（p=0.03）、SDNN（p=0.03）、RMSSD（p=0.03）、NN50计数（p=0.03）、pNN50%（p=0.03）、RRtri（p=0.02）、SD1（p=0.01）、SD2（p=0.02）、LF ms²（p=0.01）、HF ms²（p=0.03）。SDNN、SD2与HF ms²与甘油三酯呈负相关（SDNN p=0.04；SD2 p=0.04；HF ms² p=0.04）。未发现心率变异性指标与其余变量存在统计学显著相关性。所有分析的统计学显著性阈值均设定为5%。结论：乳腺癌女性的自主神经调节功能受损，且此类人群的心率变异性指标与甘油三酯水平呈负相关。