title: Prevalence and characteristics of sleep apnoea in patients with stable heart failure: Results from a heart failure clinic.
abstract: BACKGROUND
  Heart failure (HF) and sleep apnoea (SA) association has been recognized but whether it results from confounding factors (hypertension, ischaemia, obesity) remains unclear.We aimed to determine the prevalence of SA in HF and to identify potential risk factors for SA in HF population.
  
  
  METHODS
  We prospectively evaluated 103 patients with stable HF on optimized therapy. In-laboratory polysomnography was performed. Type and severity of SA were defined according international criteria. Demographic, anthropometric and clinical characteristics were collected. Continuous data are expressed as median and interquartile range.
  
  
  RESULTS
  SA was found in 72.8%, moderate to severe in a significant proportion (apnoea-hypopnoea index > or = 15- 44.7% of all patients) and predominantly obstructive (60.0% of patients with SA). Most patients were non-sleepy (Epworth < 10- 66%). SA patients were predominantly men (85.3 vs 60.7%, p-0.015), had larger neck (38.0 (35.0-42.0) vs 35.0 (33.2-38.0) cm, p-0.003), severe systolic dysfunction, (63.9 vs 33.3%, p-0.018), left ventricle (LV) hypertrophy (16.2 vs 0.0%, p-0.03), LV and left atria (LA) dilatation (49.0 (44.0-52.0) vs 42.0 (38.0-48.0) mm, p < 0.001; 60.0 (54.0-65.0) vs 56.0 (52.0-59.0) mm, p-0.01). However, only LA diameter was an independent predictor of SA. Higher body-mass index (BMI) was associated with moderate to severe SA. Patients with obstructive SA had larger neck and a trend for higher BMI, snoring and sleepiness. Hypocapnia was not associated with central SA.
  
  
  CONCLUSIONS
  In our HF population, SA was prevalent, frequently asymptomatic and without characteristic risk factors. Unlike previously reported, obstructive SA was the predominant type. These results suggest that SA is underdiagnosed in HF and there is a possible correlation between them, independent of confounding factors. Recent advances in HF therapy might influence prevalence and type of SA in this population.
authors.affiliation: Internal Medicine Department, São João Hospital, Oporto Medical University, Cardiovascular Research Unit, Alameda Professor Doutor Hernâni Monteiro, 4200-319 Porto, Portugal. susanaferreira14@hotmail.com
authors.forename: Susana
authors.initials: S
authors.lastname: Ferreira
authors.forename: Anabela
authors.initials: A
authors.lastname: Marinho
authors.forename: Marta
authors.initials: M
authors.lastname: Patacho
authors.forename: Elisabete
authors.initials: E
authors.lastname: Santa-Clara
authors.forename: Cristina
authors.initials: C
authors.lastname: Carrondo
authors.forename: João
authors.initials: J
authors.lastname: Winck
authors.forename: Paulo
authors.initials: P
authors.lastname: Bettencourt
mesh_terms: D000368:Aged; D015992:Body Mass Index; D005260:Female; D006333:Heart Failure / Q000453:epidemiology*; D006801:Humans; D016857:Hypocapnia / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010044:Outpatient Clinics, Hospital / Q000706:statistics & numerical data*; D017286:Polysomnography; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology*; D012894:Sleep Stages; D012913:Snoring / Q000453:epidemiology