RESUMO
INTRODUCTION AND OBJECTIVES: Alterations of the sympathetic and parasympathetic nervous system have been proposed as precursors of the genesis and perpetuation of atherosclerosis for a long time. The objective of this study is to determine if there is an association between the presence of carotid atherosclerosis and the reduction in heart rate variability. METHODS: Using a prospective case-control design, the heart rate variability and the presence of carotid atherosclerosis was investigated in 54 patients, divided into 2groups according to the presence or absence of carotid atherosclerosis. An analysis was made of the heart rate variability variables of the frequency (spectral) domain in high frequency band, low frequency band, parasympathetic autonomic balance, and the total spectral band. RESULTS: Of the 54 individuals evaluated without previous cardiovascular disease consecutively, 26 of them (48%) presented with subclinical carotid atherosclerosis (ATE+). A reduction in heart rate variability was observed in the ATE+group represented by the low frequency (LF) spectrum (P<.0001). The parasympathetic activity specifically represented in the high frequency (HF) band was also lower in the ATE+group in the univariate analysis (P<.0001), same as the total spectral power (P<.0001), an index of integral autonomic regulation. No significant differences were found in the LF/HF analysis (P=.1598). After analysing variables with significant differences in the univariate analysis with a logistic regression model, only systolic blood preassure and the total spectral power were shown to be independent predictors of ATE+. CONCLUSION: A reduction in heart rate variability was found in subjects with carotid atherosclerosis. Some spectral components of heart rate variability, like low frequency or total spectral power, were better predictors of carotid atherosclerosis than the parasympathetic autonomic balance. In this study it seems that total spectral power is an adequate measurement for analysing autonomic function.