Cardiovascular effects of oral appliance therapy in obstructive sleep apnea: A systematic review and meta-analysis

Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity and mortality. This study systematically reviews the effects of oral appliance therapy (OAT) on a broad spectrum of cardiovascular outcomes. A literature search was performed up to December 31st 2016. Twenty-five relevant full-text articles were retrieved. Sixteen articles were considered methodologically sufficient, including 11 randomized controlled trials. Pooled data of the RCTs showed significant reductions in daytime systolic and diastolic blood pressure compared to baseline, but no significant reductions in heart rate, except for daytime heart rate when compared to inactive/placebo OAT. OAT and continuous positive airway pressure (CPAP) were equally effective in reducing blood pressure. Studies assessing the effect of OAT on heart rate variability, circulating cardiovascular biomarkers, and endothelial function and arterial stiffness, generally involved small numbers of patients, and were heterogeneous and inconclusive. Studies assessing the effect of OAT on cardiac function showed no effects on echocardiographic outcomes. One observational study showed that OAT was as effective as CPAP in reducing cardiovascular death. It could be speculated that OAT may lead to a reduction in long-term cardiovascular morbidity and mortality in OSA patients. However, further methodologically high quality, longitudinal studies are warranted to address this key question.