Acute Effect of Continuous Positive Airway Pressure in Heart Failure

Acute effects of CPAP on diastolic function in patients with compensated heart failure (CHF) are unknown. The investigators hypothesized that acutely CPAP improves diastolic function, which is associated with increases exercise tolerance. Objective: To evaluate the acute effects of CPAP on functional capacity and diastolic indices of patients with CHF. This is a randomized trial including 44 patients with compensated heart failure (functional classes II or III, NYHA). Patients will be allocated in CPAP(CPAP with 10cmH2O) or simulated CPAP (null pressure) after computed randomization, in a 1:1 ratio. All subjects shall complete a 6-minute walk test (6MWT) before and after CPAP (30 minutes; 10 cm H2O pressure). Doppler-echocardiogram will be performed before and at the end of CPAP. Wilcoxon or paired t tests were used to compare results, with significance level at p \< 0.05.