OSA may affect as many as 50% of patients with established cardiovascular diseases referred to tertiary cardiology centers. However, OSA remains largely underrecognized in this group of patients in clinical practice. Why is that? One possible explanation is that many nonsleep specialists are not familiarized with OSA diagnosis and treatment. There may also be a perception that the causal link between OSA and cardiovascular diseases remains to be clearly established. Perhaps this is related to the fact that the field lacks large clinical trials showing benefits of OSA treatment on cardiovascular outcomes. On the other hand, it is also possible that sleep specialists have taken for granted that OSA is harmful to the cardiovascular system long before the link was fully established because of the observation that patients with severe OSA experience dramatic episodes of recurrent suffocation during sleep, causing large intrathoracic pressure swings and progressive hypoxia that must putatively harm the cardiovascular system.