Aortic stiffness increases in proportion to the severity of apnoea-hypopnea index in patients with obstructive sleep apnoea syndrome

Background and aims: Obstructive sleep apnoea syndrome (OSA) and aortic stiffness are associated with an increased risk of cardiovascular morbidity and mortality. Although aortic stiffness increased in patients with OSA, the relationship between severity of OSA indicated with apnoea-hypopnea index (AHI) and aortic stiffness was not investigated in previous studies. The aim of this study is to investigate the relationship between the severity of OSA and aortic stiffness.

Methods: In the present study, 90 consecutive OSA patients definite diagnosed with sleep test were prospectively included (mean age 54.5 ± 11.6 years). Aortic pulse wave velocity (PWV) and augmentation index (AIx) were calculated using the single-point method via the Mobil-O-Graph® ARCsolver algorithm. Aortic distensibility (AD) was calculated from the echocardiographically derived ascending aorta diameters and haemodynamic pressure measurements. Overnight full-laboratory polysomnography examination was conducted on each subject. Patients were classified into two groups according to their median AHI values (AHIlow and AHIhigh groups).

Results: PWV values were higher and AD values were lower in AHIhigh group compared with AHIlow group (P < 0.05, for all). AHI was associated with body mass index (BMI), systolic blood pressure, pulse pressure, aortic diameter, AD, AIx and PWV in bivariate analysis (P < 0.05, for all). Multivariate linear regression analysis showed that AHI was independently associated with BMI (β = 0.175, P = 0.047), PWV (β = 0.521, P < 0.001) and aortic distensibility (β = -0.223, P = 0.020).

Conclusions: Aortic stiffness is associated both with the presence and the severity of OSA.