The effect of continuous positive airway pressure therapy on arterial stiffness and endothelial function in obstructive sleep apnea: a randomized controlled trial in patients without cardiovascular disease

Abstract Background Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity and mortality which may be mediated by increased arterial stiffness and endothelial dysfunction. Continuous positive airway pressure (CPAP) therapy improves excessive daytime somnolence (EDS), but its effect on vascular function in patients without preexisting cardiovascular disease (CVD) is unclear. Methods Fifty-three patients with OSA defined as an apnea–hypopnea index (AHI) of ⩾15 and without CVD were recruited into a double-blind, randomized, placebo-controlled, crossover trial of 12 weeks of CPAP therapy, of whom 43 participants completed the study protocol. Arterial stiffness was assessed by measuring the augmentation index (AIx) and pulse wave velocity (PWV) by applanation tonometry and cardiovascular magnetic resonance imaging to determine aortic distensibility. Endothelial function was assessed by measuring vascular reactivity after administration of salbutamol and glyceryl trinitrate. Results CPAP therapy lowered systolic blood pressure (SBP) (126 mmHg [standard deviation {SD}, 12] vs 129 mmHg [SD, 14]; P = .03), with a trend towards reduced AIx (15.5 [SD, 11.9] vs 16.6 [SD, 11.7]%; P = .08) but did not modify endothelial function. When subjects with ( n = 24) and without ( n = 19) EDS were separately examined, no effect of CPAP therapy on vascular function was seen. Conclusions In patients without overt CVD, CPAP therapy had a nonsignificant effect on AIx and did not modify endothelial function.