title: Relationship of left atrial size to obstructive sleep apnea severity in end-stage renal disease.
abstract: BACKGROUND
  Increased left atrial (LA) size is linked to elevated mortality in end-stage renal disease (ESRD). In addition, the degree of overnight rostral fluid shift from the legs is associated with severity of obstructive sleep apnea (OSA). As rostral fluid shift might distend the left atrium and increase fluid accumulation in the neck, we postulated that LA size would be related to the degree of overnight rostral fluid shift and OSA severity in ESRD patients.
  
  
  METHODS
  Patients with ESRD underwent echocardiography and polysomnography. Leg fluid volume (LFV) was measured by bioelectrical impedance before and after the overnight sleep study in a subset of 21 patients.
  
  
  RESULTS
  Forty patients (22 men), with a mean apnea-hypopnea index (AHI) of 25.1 ± 23.4/h of sleep, had echocardiography and polysomnography performed. In men, there was a correlation between the AHI and LA size indexed for body surface area (r = 0.743, p < 0.001) that was not observed in women. Strong relationships were seen, again in men only, between LA size indexed to body surface area and the overnight change in leg fluid volume (ΔLFV) (r = -0.739, p = 0.02) and between AHI and ΔLFV (r = -0.863, p = 0.003).
  
  
  CONCLUSIONS
  In ESRD patients, there are relationships between ΔLFV and both LA size and OSA severity. These findings suggest that the relationship between LA size and mortality in ESRD may be related to ΔLFV and severity of OSA.
authors.affiliation: Sleep Research Laboratory, University Health Network Toronto Rehabilitation Institute, Toronto, ON, Canada; Centre for Sleep Medicine and Circadian Biology, University of Toronto, Toronto, ON, Canada.
authors.forename: Owen D
authors.initials: OD
authors.lastname: Lyons
authors.affiliation: Department of Medicine, University Health Network Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Chan
authors.affiliation: Sleep Research Laboratory, University Health Network Toronto Rehabilitation Institute, Toronto, ON, Canada; Centre for Sleep Medicine and Circadian Biology, University of Toronto, Toronto, ON, Canada; Department of Medicine, University Health Network Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Rosilene M
authors.initials: RM
authors.lastname: Elias
authors.affiliation: Sleep Research Laboratory, University Health Network Toronto Rehabilitation Institute, Toronto, ON, Canada; Centre for Sleep Medicine and Circadian Biology, University of Toronto, Toronto, ON, Canada; Department of Medicine, University Health Network Toronto General Hospital, Toronto, ON, Canada. Electronic address: douglas.bradley@utoronto.ca.
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D004452:Echocardiography; D005260:Female; D006325:Heart Atria / Q000473:pathology*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D017286:Polysomnography; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications*
keywords: Cardiovascular; End-stage renal disease; Fluid shift; Left atrium; Men; Obstructive sleep apnea