Coronary artery disease and obstructive sleep apnea

Abstract

Epidemiologic data suggest that obstructive sleep apnea (OSA) is overrepresented in patients with coronary artery disease (CAD). Although interventional studies have not yet convincingly demonstrated increased survival after continuous positive airway pressure (CPAP) in asymptomatic patients with CAD and OSA, there are data suggesting that OSA may enhance the clinical course of CAD. Experimental data demonstrates that OSA, by means of phenomena such as intermittent hypoxemia and reoxygenation, may initiate a sequence of events involved in the development of atherosclerotic disease. Development of vascular disease and CAD is influenced by several risk factors that also have been associated with OSA. Sleep apneic events induce a state of increased cardiac oxygen demand, which is simultaneous with low oxygen reserve due to lack of ventilation. Nocturnal angina may therefore be triggered by OSA in patients with CAD. Observational data suggest that elimination of sleep apneas by CPAP can benefit patients at risk of CAD in the immediate and long term in sleep clinic cohorts with OSA-related symptoms, such as excessive daytime sleepiness. However, the majority of CAD patients with OSA do not report daytime sleepiness, and recent randomized controlled trials have failed to demonstrate cardiovascular benefits of CPAP in intention-to-treat populations. This lack of efficacy of CPAP in CAD patients may be explained by a low adherence to CPAP. In addition, randomized trials have consistently included a nonsleepy OSA phenotype for ethical reasons. Hence the exact interaction between OSA and CAD awaits further insights on whom and when to treat. The current chapter reviews the clinical and epidemiologic evidence behind the relationship between CAD and OSA, as well as the impact of treatment on cardiovascular outcomes. The potential pathophysiologic mechanisms involved in the association between these two conditions will be highlighted. © 2022 Elsevier Inc. All rights reserved.