ABC | Volume 110, Nº4, April 2018

Original Article Heart Rate and its Variability Assessed by Spectral Analysis in Elderly Subjects with Orthostatic Hypotension: A Case-Control Study Rose Mary Ferreira Lisboa da Silva, Carlos Eduardo de Souza Miranda, Maira Tonidandel Barbosa, Maria Aparecida Camargos Bicalho Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, MG - Brazil Mailing Address: Rose Mary Ferreira Lisboa da Silva • Avenida Prof. Alfredo Balena, 190, sala 246, Centro, Belo Horizonte, MG - Brazil E-mail: roselisboa@cardiol.br , roselisboa@uol.com.br Manuscript received May 02, 2017, revised manuscript October 12, 2017, accepted November 09, 2017 DOI: 10.5935/abc.20180043 Abstract Background: The prevalence of orthostatic hypotension (OH) increases with age and is associated with changes in autonomic regulation of blood pressure (BP) and heart rate (HR). Objective: to assess HR and HR variability (HRV) in elderly subjects with OH and determine OH predictors. Methods: a total of 105 patients aged≥60 years, 39 withOH (case group) and 66 without OH (control group) (age-matched) were studied. Patients underwent clinical assessment, electrocardiogram, biochemistry tests and Holter monitoring for spectral analysis of HRV (Fourier transform) in the supine and orthostatism positions to identify low frequency (LF) and high frequency (HF) components, as well as the LF/HF ratio. Results: median age was 73.0 years, 64 patients were women. In all participants, there was a reduction in HF (133.0 versus 76.0 ms 2 , p = 0.001) and increase in LF/HF (1.6 vs 2.1; p < 0.001) and no change in LF (233.0 versus 218.0 ms 2 , p = 0.080). Between-group comparisons revealed significant differences in the median values of HR in the supine position (62.0 vs. 69.0 bpm, p = 0.001) and LF in the supine position (157.0 in case group vs. 275.0 ms 2 in the control group, p = 0.014). Spearman’s correlation coefficient of 0.27 was found between the groups. Multivariate analysis revealed that HR in the supine position was an independent variable for OH (p = 0.001- 95%CI = -0.022 and -0.006). Using the operating characteristic curve, the best cutoff point was 61 bpm, with a sensitivity of 77.3% and specificity of 51.3%, positive predictive value of 61.3%, and negative predictive value 69.3%. Odds ratio was 3.23 for OH in patients with a HR lower than 61 bpm. Conclusions: lower LF and HR in the supine position were found in patients with OH, regardless of age and gender. The independent predictor for OH was HR in the supine position, with an odds ratio of 3.23 for values lower than 61 bpm. (Arq Bras Cardiol. 2018; 110(4):303-311) Keywords: Heart Rate; Hypotension, Orthostatic; Accidental Falls; Syncope; Aged; Dizziness. Introduction Orthostatic hypotension (OH), also known as postural hypotension is defined as a sustained fall in blood pressure (of at least 20 mm Hg in systolic pressure and/or at least 10 mm Hg in diastolic pressure) occurring within 3 minutes of standing. 1,2 OH has been associated with falls, presyncope, syncope, functional impairment in the elderly, cardiovascular events, and increased mortality. 3-5 Its prevalence varies from 6 to 35%, 4 and can achieve 41% in individuals aged 80 years or older. 6 With aging, there are changes in autonomic regulation of heart rate (HR) and blood pressure. Middle-aged women have a more dominant parasympathetic whereas men have a more sympathetic regulation of heart rate. 7 In addition, increased levels of norepinephrine and reduced sensitivity of beta-adrenergic receptors are found in elderly subjects. There is a decrease in vasomotor response mediated by alpha receptors, with decline in venous capacitance response of the lower limbs and in baroreflex response, which is also due to artery stiffness. 8,9 This altered regulation lead to autonomic dysfunction and may cause OH. Autonomic nervous system, involved in the physiopathology of OH, may be examined by measurements of the heart rate variability (HRV) by Holter monitoring, 10 a non-invasive, low-cost method. Studies on the autonomic nervous system, including those on baroreflex sensitivity and head-up tilt test have been performed in hypertensive and normotensive elderly patients who were compared with young subjects. These studies included up to 80 elderly subjects, 64 with hypertension. 11-13 In the largest study, involving 362 volunteers, there were 38 men and 51 women aged between 57 and 88 years, 13 but the authors did not specify the exact number of older patients. In light of this, this study aimed to assess HR and HRV by spectral analysis during postural tilt in elderly patients, and evaluate OH predictors. 303