Does Treatment for Obstructive Sleep Apnoea Improve Arterial Stiffness? Evidence from Randomized Clinical Trials on Carotid-femoral Pulse Wave Velocity

Obstructive Sleep Apnoea (OSA) is a breathing disorder characterized by narrowing of the upper airway that impairs normal ventilation during sleep. OSA is a highly prevalent condition which is associated with several Cardiovascular (CV) risk factors and CV diseases. Despite this clear association, Randomized Controlled Trials (RCTs) have provided equivocal data that treatment of sleep apnoea can improve CV outcomes regardless of its ability to reduce blood pressure. Here, we critically review the evidence that supports role of OSA as a risk factor for increased arterial stiffness which represents an early manifestation of vascular damage often preceding major CV events. Additionally, we examined evidence from interventional RCTs to assess if treatment of OSA by continuous positive airway pressure can affect arterial stiffness measured as carotid-femoral pulse wave velocity. Overall, a large body of evidence supports the role of OSA as a risk factor for increased arterial stiffness and several pathophysiological mechanisms, including activation of the autonomic nervous system, may help to explain the link between breathing disorders and vascular alterations (here mainly examined as functional properties). Whether the causal relationship between OSA and vascular damage exists or is mostly explained by confounders and whether OSA treatment can improve vascular stiffening is still debated.