OSA and Ischemic Heart Disease in the Elderly

Obstructive sleep apnea (OSA) is associated with increased incidence of both cerebrovascular and coronary events and of overall cardiovascular risk. However, it seems that these relationships are less clear in the elderly population. On the other hand, continuous positive airway pressure (CPAP), the treatment of choice for severe and symptomatic OSA patients, seems to be more effective in preventing cerebrovascular than coronary events, also in the elderly. This review describes the existing literature in the field and exposes the different hypotheses that try to explain these phenomena. There is a growing body of evidence showing that low-grade intermittent hypoxia (a feature that characterized OSA) is associated with increased levels of hypoxia-inducible factor 1 (HIF-1) and vascular endothelial growth factor (VEGF) which in turn lead to neovascularization in the coronary tree (preconditioning hypoxia hypothesis). However, little is known about the effect of intermittent hypoxia in the formation of new vessels in the cerebral vasculature. Moreover, the effect of intermittent hypoxia in both coronary and cerebral vessels could change with age. On the other hand, recent randomized clinical trials have shown that CPAP may not be effective in preventing cardiovascular events in the context of secondary prevention. However, a more detailed analysis of the results and subsequent meta-analyses show that this treatment exerts a protective effect in cerebrovascular disease but not in cardiovascular diseases, especially in elderly patients. Although OSA is clearly related to an increased cardiovascular risk, this seems less obvious in the elderly and in the coronary vessels. As a consequence, the effect of CPAP in the elderly with coronary disease remains controversial.