Oxygen Therapy in Patients With Chronic Heart Failure With Reduced Ejection Fraction

The purpose of this study is to assess patients with chronic heart failure and moderate-severe ventricular dysfunction (left ventricular ejection fraction (FEVE) \<40%) with nocturnal desaturation (mean Oxygen saturation (SatO2) \<90% and/or Cummulative time (TC) \<90% \> 22 minutes) without underlying respiratory disease, oxygen treatment during hours of night rest will reduce exacerbations, improve the ability to effort, sleep quality and poor prognostic parameters of heart failure, compared to patients not receiving oxygen treatment.