title: Nocturnal hypoxaemia is associated with increased mortality in stable heart failure patients.
abstract: This study investigated the prognostic value of sleep-disordered breathing (SDB) in a large cohort of patients with heart failure with reduced left ventricular function (HF-REF), with focus on the role of nocturnal hypoxaemia.
  
  
  
  This single-centre prospective cohort study enrolled patients with chronic stable HF-REF (NYHA ≥II) receiving guideline-based treatment. Unattended in-hospital polygraphy was performed to determine the apnoea-hypopnoea index (AHI). Pulse oximetry was used to determine hypoxaemic burden [time with oxygen saturation <90% (T90)], and all-cause mortality was recorded.
  
  
  
  Complete data were available for 963 of 1249 patients. At baseline, 58% of patients had moderate-to-severe SDB. The median follow-up was 7.35 years; 480 of 963 (49.8%) patients died. Mortality rate (per 100 person-years) was 8.1 [95% confidence interval (CI) 7.0-9.4] in patients with no or mild SDB, but 12.2 (95% CI 10.9-13.7) in moderate-to-severe SDB. Apnoea-hypopnoea index was significantly associated with time to death from any cause in a simple Cox model [hazard ratio (HR) 1.011, P < 0.001], but was no longer significant after adjustment for confounding factors (HR 1.005, P = 0.085). T90 was significantly (P < 0.001) associated with time to death from any cause even after adjustment for confounding factors. The risk of death increased by 16.1% (95% CI 8.6-24.2) per hour of T90. Five-year survival probabilities for patients in T90 quartiles 1, 2, 3, and 4 were 70, 63, 60, and 50%, respectively.
  
  
  
  Hypoxaemic burden was a robust and independent predictor of all-cause mortality in chronic stable HF-REF patients. Whether or not targeting nocturnal hypoxaemia is associated with beneficial effects on mortality in HF-REF patients remains to be determined.
authors.affiliation: Department of Cardiology, Heart and Diabetes Center North Rhine-Westphalia, Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany akleemeyer@hdz-nrw.de.
authors.forename: Olaf
authors.initials: O
authors.lastname: Oldenburg
authors.affiliation: Department of Cardiology, Heart and Diabetes Center North Rhine-Westphalia, Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Wellmann
authors.affiliation: Department of Medical Biometry and Epidemiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Anika
authors.initials: A
authors.lastname: Buchholz
authors.affiliation: Department of Cardiology, Heart and Diabetes Center North Rhine-Westphalia, Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bitter
authors.affiliation: Department of Cardiology, Heart and Diabetes Center North Rhine-Westphalia, Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
authors.forename: Henrik
authors.initials: H
authors.lastname: Fox
authors.affiliation: Department of Medical Informatics, Biometry and Epidemiology, Ruhr-University Bochum, Bochum, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Thiem
authors.affiliation: Department of Cardiology, Heart and Diabetes Center North Rhine-Westphalia, Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Horstkotte
authors.affiliation: Department of Medical Biometry and Epidemiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Wegscheider
mesh_terms: D000368:Aged; D005260:Female; D006333:Heart Failure / Q000401:mortality*; D006801:Humans; D000860:Hypoxia / Q000401:mortality*; D053208:Kaplan-Meier Estimate; D008297:Male; D010092:Oximetry; D017286:Polysomnography; D011446:Prospective Studies; D020182:Sleep Apnea, Central / Q000401:mortality*; D020181:Sleep Apnea, Obstructive / Q000401:mortality*
keywords: Heart failure; Hypoxaemia; Mortality; Sleep-disordered breathing