AimsSleep disordered breathing (SDB) may contribute to disease progression in patients with chronic heart failure (CHF). The objective of this observational study was to evaluate whether SDB is a risk factor for mortality in CHF patients and whether this risk can be attenuated by treatment with positive airway pressure (PAP). ) and (ii) evaluated the impact of PAP treatment on mortality in those with severe SDB. After accounting for significant confounding factors (age, NYHA class, cause of CHF, diabetes, and PAP treatment), patients with severe SDB (n ¼ 176) had a 2.0-fold increased hazard ratio for death compared with those without severe SDB [95% confidence interval (CI) 1.1 -3.5, P ¼ 0.023]. In an adjusted on-treatment analysis of the group with severe SDB, mortality was significantly less in patients using PAP (18%) compared with those with untreated SDB (52%; hazard ratio 0.4, 95% CI 0.2-0.6, P ¼ 0.001). Mortality in the PAP-treated group was lower compared with the untreated group at any time-point of the follow-up period. Methods and results We ConclusionThe presence of severe SDB in CHF patients constitutes a significantly increased risk for death, independent of established risk factors. In CHF patients with SDB, use of PAP therapy was associated with a decreased mortality rate at any time point of the follow-up, suggesting that PAP can be safely used in such patients.--