Effects of acute dopamine-agonist treatment in restless legs syndrome on heart rate variability during sleep

Abstract

Objective: To compare heart rate variability (HRV) changes in patients with restless legs syndrome (RLS) and in healthy subjects, and to evaluate HRV before and after treatment with pramipexole in RLS patients.

Methods: A prospective, polysomnographic, single-blind, placebo-controlled study was performed in 23 patients with RLS and 10 healthy subjects. Basal spectral analysis of HRV and phasic heart rate (HR) changes during PLMS were compared between the two groups and, within the RLS group, before and after treatment with placebo or pramipexole.

Results: No differences were found in the basal sympathovagal balance outside of PLMS between RLS and controls and, in the RLS group, before and after treatment. The amplitude of PLMS-related HR changes was higher in patients than in controls. Treatment with pramipexole decreased the number of PLMS and normalized the increased PLMS-related HR response in RLS subjects.

Conclusions: The repetitive abnormal autonomic response to PLMS might play a role in the increased cardiovascular risk proposed for RLS patients. Pramipexole reduced the number of PLMS and the amplitude of the autonomic response to residual PLMS, without effects on the tonic sympathovagal regulation. D3 receptors in the sympathetic pre-ganglionic neurons of the spinal intermediolateral columns might be a target of pramipexole. The normalization of the HR response could be relevant in reducing the risk of cardiovascular diseases and associated autonomic dysfunctions in patients with RLS.