Relationship between heart rate variability and carotid intima-media thickness in the Brazilian Longitudinal study of Adult health - ELSA-Brasil.

BACKGROUND: Both increased carotid intima-media thickness (cIMT) and low heart rate variability (HRV) have been associated with cardiovascular mortality and morbidity. Thus, the aim of this study was to investigate whether cardio autonomic alterations are accompanied or not by subclinical atherosclerosis in participants of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). METHODS: cIMT measures and 5-min HRV analyses were performed in apparently healthy adults. Heart rate variability was evaluated by linear time and frequency domain analyses. cIMT was defined as the average between the mean left and mean right cIMT values and was analysed as continuous and categorized variables (P>/=75 or P /= 75th percentile. Heart rate variability variables were reduced in cIMT >/= P75 in comparison with cIMT /= P75 was verified within the lowest two quartiles of LF and HF, but significances did not remain after adjustments for anthropometric and clinical variables. CONCLUSIONS: Considering the entire sample, subjects with cIMT >/= P75 presented lower HRV values, but no independent relationships were detected between cIMT and HRV after multivariate adjustment.