Obstructive sleep apnea syndromes (OSAS) have been demonstrated to be highly prevalent in patients with resistant hypertension (defined as uncontrolled clinic BP despite being on anti-hypertensive treatment with at least 3 drugs in optimal doses and including a diuretic). Nevertheless, the effect of treating OSAS with Continuous Positive Airway Pressure (CPAP) device on clinic and ambulatory BPs in patients with resistant hypertension is largely unknown. Hence, the primary aim of this randomized clinical trial is to evaluate the effect of CPAP on BP levels in resistant hypertensive patients with moderate-severe OSAS (defined as an apnea-hypopnea index \[AHI\] greater than 15 on a full polysomnographic examination). Two-hundred patients will be randomly allocated either to treatment with CPAP device plus their usual anti-hypertensive treatment or to continue their usual treatment alone for 6 months. Clinic and 24-hour ambulatory BP monitoring, laboratory evaluation (including microalbuminuria and aldosterone-to-renin ratio), 24-hour Holter monitoring, ergospirometric treadmill test, and carotid-femoral pulse wave velocity measurement will be performed before and after the 6-month treatment, with the observers blinded to the allocation group.
