Treatment of sleep apnea in heart failure

Obstructive and central sleep apnea are common in heart failure, and may participate in its progression by exposing the heart to intermittent hypoxia, increased preload and afterload, sympathetic activation, and vascular endothelial dysfunction. Treatment of sleep apnea in patients with heart failure may reverse these detrimental effects, in addition to alleviating symptoms of sleep apnea. In patients with heart failure and obstructive sleep apnea, short-term randomized trials have demonstrated that continuous positive airway pressure (CPAP) improves cardiac function, and lowers sympathetic activity and blood pressure. However, there are no data on whether treating obstructive sleep apnea in patients with heart failure improves morbidity and mortality. Various treatments have been tested in heart failure patients with central sleep apnea, particularly oxygen and CPAP. Both reduce the frequency of central respiratory events, and lower sympathetic activity. In addition, CPAP improves cardiac function. However, the largest randomized trial did not demonstrate any beneficial effect of CPAP on the rate of mortality and cardiac transplantation (32 vs. 32 events in the control and treatment groups, respectively; p=0.54), but ultimately lacked power to conclude with certainty whether CPAP has an effect on morbidity and mortality in such patients. Thus, although there are data to indicate that treating both obstructive and central sleep apnea in patients with heart failure improves cardiovascular function, larger randomized trials involving interventions such as oxygen, CPAP, or other forms of positive airway pressure will be required to determine whether treating these sleep-related breathing disorders reduces clinically important outcomes such as morbidity and mortality.