We recently read with great interest the article by Masa et al, published in CHEST (July 2016), in which the authors examined the association between OSA severity and cardiovascular morbidity in patients with obesity hypoventilation syndrome (OHS). Surprisingly, their results showed an inverse relationship between cardiovascular morbidity and severity of OSA, except for ischemic heart disease. As hypothesized by Lavie and Lavie, the cycles of apneic/hypopneic events in OSA that resemble cycles of ischemia/reperfusion could exert a protective effect from more severe ischemic and cardiovascular events, similar to ischemic preconditioning. There is the possibility that these factors may be a particular characteristic of OHS. Moreover, Cadby et al reported an independent association between the presence and severity of OSA and incident atrial fibrillation in a large clinic-based cohort group over a median 12-year follow-up period. What is the role of nocturnal hypoventilation and of tonic desaturation in the etiopathogenesis of cardiologic comorbidity?