Abstract 483: Extracranial Artery Disease is Associated With An Impairment of Cardiac Autonomic Control

Abstract

Background: Atherosclerotic intima-media thickening (IMT) of carotid or subclavian artery may be associated with alterations in the sensitivity of carotid and subclavian baroreceptors. This is why we aimed at investigating if IMT is associated with alterations in the autonomic modulation of heart rate variability (HRV). Methods: This was a cross-sectional study with 30 subjects. The atherosclerotic artery IMT was determined by B-mode and duplex ultrasonography. HRV was evaluated through linear (low frequency [LF, ms2], high frequency [HF, ms2], standard deviation (SD) of normal R-R wave intervals [SDNN], square root of the mean of the sum of the squares of differences between adjacent normal R wave intervals [RMSSD]) and nonlinear Poincaré analysis (SD of the points perpendicular to the line-of-identity [SD1, ms]; SD along the line-of-identity [SD2, ms]). Results: A significant negative linear correlation was identified between the IMT of common carotid artery and the HRV indexes that reflects baroreflex and the fluctuations of autonomic tone: LF, Spearman's r = -0.52, 95% CI: -0.75 to -0.19, P = 0.003; SDNN, Spearman's r = -0.57, 95% CI: -0.78 to -0.25, P = 0.001; SD2, Spearman's r = -0.59, 95% CI: -0.79 to -0.28, P = 0.0006. Similar strong negative correlations were found for subclavian IMT. In contrast, there was no relationship between IMT and the HRV indexes related to autonomic tone (HF, LF/HF, RMSSD, SD1, SD1/SD2). The receiver operating characteristic (ROC) sensitivities/specificities/area under curve of SD2 for predicting carotid and subclavian artery IMT were 0.75/0.83/0.81 and 0.70/0.69/0.70, respectively (cutoff values: <32.8 and <42.5, respectively). Identification of atherosclerotic plaque in subclavian artery (IMT > 1.5 mm) was associated with a drastic reduction of SD2 (25.9 [24.3-40.5] vs. 50.2 [38.1-68.7]; data are median and interquartile range values, p = 0.0009), LF (65% lower, p = 0.005) and SDNN (43% lower, p = 0.001). Conclusions: Our data demonstrate that the atherosclerotic carotid and subclavian IMT are associated with an impairment of cardiac autonomic control. The SD2 index of Poincaré plot may be a functional biomarker for subjects at risk for carotid disease and an indicator for ultrasound evaluation.