Obstructive sleep apnea and cardiovascular comorbidity: modern discordance in assessing the effectiveness of CPAP-therapy against the pathogenetic mechanisms and cardiovascular diseases

Abstract

Sleep-disordered breathing (and obstructive sleep apnea, OSA) is a common pathology in the general population in economically developed countries. In the last decades, CPAP therapy (continuous positive airway pressure) became the first-choice treatment option in clinically relevant OSA.Objective. The review summarized available evidence about the effects of CPAP-therapy on the main pathogenetic pathways of OSA (sleep-related sympathetic activity, vascular inflammation, endothelial dysfunction, oxidative stress, and blood coagulation) and cardiovascular diseases (CVDs - hypertension, cardiac arrhythmias, heart failure, pulmonary hypertension, coronary heart disease, and combined cardiovascular outcomes, including cardiovascular mortality).Methods. We analyzed the data of the randomized observational cohort clinical trials and metaanalyses, which assessed the effects of CPAP-therapy on the pathophysiological mechanisms of OSA and the associated CVDs. We also analyzed current guidelines on the management of patients with CVDs and OAS. We searched the following databases: Scopus, Pubmed, Google Scholar, Russian Scientific Citation Index.Results. Despite the rather recent implementation of this method, the accumulated evidence shows its favorable impact on OSA pathogenesis (on sympathetic activity and, to some extent, on vascular inflammation and endothelial dysfunction) and CVDs (hypertension, in particular, resistant hypertension, and paroxysmal atrial fibrillation). The observational studies also demonstrate favorable outcomes regarding other CVDs. However, the data of the randomized clinical trials are limited or controversial, the samples are rather small, which leads to inconsistent conclusions.Conclusion. Currently, most of the researchers emphasize that the required CPAP-adherence level (regular use for at least 4 h nightly) is the main barrier to getting the high-level evidence of CPAP efficiency with regard to the cardiovascular risk. This factor becomes the biggest limitation in patients who are characterized by the low compliance because they are not prone to daytime sleepiness.