Arterial stiffness and heart rate variability analysis in patients with mild–moderate obstructive sleep apnoea, with and without excessive daytime sleepiness

Abstract

Background: Patients with severe obstructive sleep apnoea syndrome (OSAS) show higher risk of cardiovascular disease (CV) and exhibit an increased arterial stiffness and a deregulation of autonomic nervous system (ANS) activity. Data are lacking in patients with mild-moderate OSAS. The study aimed to analyze heart rate variability (HRV) and arterial stiffness in patients with mild–moderate OSAS, with and without symptoms of excessive daytime sleepiness (EDS). Methods: Fifty-six male patients with mild–moderate OSAS [apnoea/hypopnea index (AHI) between 5 and 30 events/hour], without any CV risk factor, underwent full polysomnography (NPSG). Patients were divided into two groups according to the Epworth Sleepiness Scale (ESS), a subjective assessment of daytime sleepiness. During the first and the last 5 minutes of NPSG, in the wake stage, and overnight we have analysed arterial stiffness index (SIDVP), derived from digital plethysmogram, and heart rate variability. Results: The two groups were matched for age, body mass index (BMI) and AHI, did not show differences in terms of arterial stiffness. Patients with an ESS >10 had similar values of SIDVP compared with patients without EDS. In terms of HRV we have found a significant difference only in low frequency (LF) power at the end of the NPSG study (LF power 14,601±7,495 vs. 21,031±14,257 ms 2 , P<0.05), with no differences in the other HRV parameters. Conclusions: Patients with mild-moderate OSAS, with or without EDS, exhibit similar arterial stiffness and HRV and therefore might have a similar CV risk.