In addition, it is well-established that OSA triggers a cascade of deleterious effects to the cardiovascular system, including sympathetic activation, oxidative stress, insulin resistance, endothelial dysfunction, and atherosclerosis. All these intermediate mechanisms may collectively contribute to the risk of coronary artery disease, stroke, and ultimately cardiovascular death. Although the treatment of OSA with CPAP is able to abolish OSA, one important question remains unanswered: can we reverse the effects of OSA on the cardiovascular system when treatment is established? One small randomized trial showed that the treatment of OSA with CPAP is able to return BP values to optimal levels in a significant proportion of patients with prehypertension and masked hypertension. An observational study from Spain showed that the treatment of OSA with CPAP in normotensive patients was able to prevent the development of hypertension. CPAP is also able to ameliorate arterial stiffness as well as markers of diastolic dysfunction in patients with OSA and no other comorbid conditions., Although surrogate cardiovascular outcomes suggest that CPAP therapy can reverse cardiovascular complications of OSA, definitive proof has remained elusive. Reversibility of cardiovascular complications is difficult to answer in humans in which a myriad of confounders such as obesity, hypertension, diabetes, and aging frequently coexist.