522 Reduced sympatho-vagal responses to orthostatic stress in drug-naïve idiopathic restless legs syndrome

Abstract

Abstract Introduction Restless legs syndrome (RLS) is a risk factor for cardiovascular disease (CVD). However, there are no electrophysiological biomarkers to assess this risk. This study aimed to evaluate the heart rate variability (HRV) and autonomic control of cardiovascular reflexes in the supine and standing positions in patients with RLS during wakefulness. Methods Fourteen drug-naïve RLS patients (12 women, 2 men; mean age: 42.14 ± 7.81 years) and 10 healthy controls underwent tests for blood pressure, heart rate when in the supine-rest and standing positions, deep breathing, and handgrip in controlled laboratory conditions. Five-minute R-R intervals in each position were collected and analyzed for HRV. Results Cardiovascular changes during deep breathing and isometric handgrip maneuvers were normal and similar between the two groups. The normalized unit of the low frequency component and low frequency/high frequency (LH/HF) ratio during standing were lower in the RLS patients than in the controls. LF/HF ratio responses during positional change from supine-rest to standing were significantly reduced in the RLS patients (RLS patients: mean ± SD, 2.94 ± 3.11; controls: 7.51 ± 5.58; P = 0.042). In Spearman’s rank correlation, ISI and PSQI were associated with HRV parameters. Conclusion The RLS patients showed reduced sympatho-vagal responses during positional change from supine-rest to standing during wakefulness, and RLS-related sleep disturbance was an important contributing factor for autonomic nervous system dysfunction. Reduced HRV responses during wakefulness might be a good predictor for CVD risk. Support (if any):