Comment on "Correlation between the activity of the autonomic nervous system and endothelial function in patients with acute coronary syndrome". Authors' reply.

INTRODUCTION The endothelium and sympathetic nervous system play an important role in the pathogenesis of acute coronary syndrome (ACS). OBJECTIVES The aim of our study was to evaluate correlations between noninvasive markers of the endothelial function and the sympathetic nervous system in patients with a recent ACS. PATIENTS AND METHODS The study included 52 patients who experienced an ACS within the previous 3 to 6 months. Endothelial function was expressed as the reactive hyperemia index (RHI), and the activity of the sympathetic nervous system--as latency and amplitude of sympathetic skin response (SSR) potentials from the 4 limbs. Linear and partial correlations between the RHI and SSR were calculated. RESULTS There were significant correlations between the RHI and the latency of the SSR in the upper limbs (r = 0.34, P = 0.02 for the right limb; and r = 0.34, P = 0.01 for the left limb). After eliminating the effects of age, sex, weight, and glomerular filtration rate, the partial correlation between the RHI and the latency of the SSR in the upper limbs remained statistically significant (r = 0.41, P = 0.004 for the right limb, and r = 0.42, P = 0.004 for the left limb). There was no correlation between the RHI and latency of the SSR during the stimulation of the lower limbs. CONCLUSIONS Our study confirmed the correlations between the sympathetic autonomic nervous system and endothelium in patients with ACS. The correlation of the RHI with the latency of the SSR was observed only in the upper limbs.