ABC | Volume 112, Nº5, May 2019

Original Article Changes in Cardiac Autonomic Modulation in Women with Breast Cancer Using Aromatase Inhibitors and the Relation with Biochemical Variables Luana Almeida Gonzaga, 1 Thais Reis Silva de Paulo, 2 Juliana Viezel, 3 Laís Manata Vanzella, 1 Ismael Forte Freitas Jr., 3 L uiz Carlos Marques Vanderlei 1 Departamento de Fisioterapia - Faculdade de Ciências e Tecnologia da Universidade Estadual Paulista (UNESP), 1 Presidente Prudente, SP – Brazil Departamento de Educação Física - Universidade Federal do Rio Grande do Norte (UFRN), 2 Natal, RN – Brazil Departamento de Educação Física - Faculdade de Ciências e Tecnologia da Universidade Estadual Paulista (UNESP), 3 Presidente Prudente, SP – Brazil Mailing Address: Thais Reis Silva de Paulo • Campus Universitário UFRN - Centro de Ciência da Saúde - Departamento de Educação Física. Postal Code 59078-970, Lagoa Nova, Natal, RN – Brazil Email: thais.reis.silva@hotmail.com Manuscript received March 27, 2018, revised manuscript August 06, 2018, accepted August 15, 2018 DOI: 10.5935/abc.20190036 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 ms 2 , HF ms 2 , LH/HF ms 2 . 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 ms 2 (p = 0.01); HF ms 2 (p = 0.03).There was an inversely proportional correlation between the indices SDNN, SD2, and HFms 2 with triglycerides (SDNN p = 0.04; SD2 p = 0.04; HF ms 2 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. (Arq Bras Cardiol. 2019; 112(5):555-563) Keywords: Aromatase Inhibitors; Breast Neoplasms; Cholesterol; Blood Glucose; Cardiovascular Dieases/prevention and control; Estrogen Replacement Therapy/adverse effects. Introduction Breast cancer is the second most common type of neoplasm in the world and the most common among women. Annually, in both developing and developed countries, about 22% of new cases arise 1 and, according to the World Health Organization, 2 in 2011 more than 508,000 deaths occurred worldwide due to this disease. Chemotherapy, radiation therapy, and hormone therapy can be used as treatment for breast cancer. These treatments are indispensable and promote positive impacts on the cure for cancer, recurrence, and metastasis; however, the side effects can cause numerous discomforts, compromising other aspects related to women's health. 3 Among the side effects precipitated by the various treatments for breast cancer, those related to hormone therapy, more specifically to the use of aromatase inhibitors (AI), deserve attention. These substances block the enzyme aromatase, responsible for the conversion of androgens to estrogens in postmenopausal women. 3–5 Estrogen is associated with a better lipid profile and an increase in the synthesis of vasodilatory enzymes, 6,7 so its reduction in women with breast cancer promoted by the use of AI, associated with its lower production in the menopausal period, may be related to a worse lipid profile and, consequently, a higher risk of cardiovascular diseases (CVD). 6,7 In this context, the evaluation of women with breast cancer who are in the menopause becomes fundamental so that CVD 555