Sleep apnea: State of the art.

Many patient with, or at risk of, cardiovascular disease have sleep disordered breathing (SDB), which can be either obstructive (with intermittent collapse of the upper airway) or central (episodic loss of respiratory drive). SDB is associated with sleep disturbance, hypoxemia, hemodynamic changes, and sympathetic activation. Such patients have a worse prognosis than those without SDB. Mask-based therapies of positive airway pressure targeted at SDB can improve measures of sleep quality and partially normalize the sleep and respiratory physiology, but recent randomized trials of cardiovascular outcomes in SDB have either been neutral (obstructive sleep apnea) or suggested the possibility of harm, likely from increased sudden death, in central sleep apnea. Alternative methods for the treatment of SDB are being explored, including implantable technologies, but these have not been studied in adequately powered randomized controlled studies. International guidelines recommend screening for SDB, which can be done easily in clinical practice, as there may be a role for the treatment of patients with obstructive sleep apnea and daytime sleepiness, or resistant hypertension, or atrial fibrillation. Further randomised outcome studies are required to determine whether mask-based treatment for SDB is appropriate for patients with chronic systolic heart failure and obstructive sleep apnea; for those with heart failure with preserved ejection fraction; and for those with decompensated heart failure. The case is made that no longer can the surrogate endpoints of improvement in respiratory and sleep metrics be taken as adequate therapeutic outcome measures in patients with sleep apnea and cardiovascular disease.