title: The relative impact of obstructive sleep apnea and hypertension on the structural and functional changes of the thoracic aorta.
abstract: BACKGROUND
  Recent studies suggest that obstructive sleep apnea (OSA) causes thoracic aortic dilatation; but it is well accepted that hypertension can cause aortic dilatation, and hypertension is a common finding in patients with OSA. We aimed to investigate the relative impact of OSA and hypertension on the structural and functional changes of the thoracic aorta.
  
  
  METHODS
  This was an echocardiography substudy of our prospective OSA study in patients with acute myocardial infarction (AMI). Ninety-four male patients who completed both echocardiography and polysomnography were recruited. OSA was defined as an apnea-hypopnea index (AHI) > or = 15/hour.
  
  
  RESULTS
  The patients' mean age was 53 +/- 10 years, and mean body mass index (BMI) was 24.6 +/- 3 kg/m2. Sixty-four (68.1%) patients had OSA; of these, 39 (41.5%) had severe OSA. Thirty-three (52.6%) of the OSA cohort had hypertension. There was no correlation between any of the echocardiographic parameters and thoracic aortic size. Stepwise multivariate regression showed that BMI (P = 0.024), older age (P = 0.044), and hypertension (P = 0.025) were the only determinants. There was no significant independent relationship between OSA/AHI and thoracic aortic size. Systolic blood pressure but notAHI correlated significantly with aortic distensibility and compliance (r = -0.40 and -0.26, P < 0.001 and 0.022, respectively).
  
  
  CONCLUSIONS
  Hypertension is a common finding in male AMI patients with OSA. In these patients, increased afterload from systemic hypertension rather than mechanical stress on the aortic wall determines the thoracic aortic size and abnormalities in aortic functional indices. BMI and age were also independent predictors of thoracic aortic dilatation.
authors.affiliation: Cardiac Department, National University Hospital, Singapore, National University Health System, Singapore. leeliching@yahoo.com
authors.forename: Li-Ching
authors.initials: LC
authors.lastname: Lee
authors.forename: Maria Consolacion
authors.initials: MC
authors.lastname: Torres
authors.forename: See-Meng
authors.initials: SM
authors.lastname: Khoo
authors.forename: Eric Y
authors.initials: EY
authors.lastname: Chong
authors.forename: Cindy
authors.initials: C
authors.lastname: Lau
authors.forename: Yemon
authors.initials: Y
authors.lastname: Than
authors.forename: Dong-Xia
authors.initials: DX
authors.lastname: Shi
authors.forename: Anand
authors.initials: A
authors.lastname: Kailasam
authors.forename: Kian-Keong
authors.initials: KK
authors.lastname: Poh
authors.forename: Chi-Hang
authors.initials: CH
authors.lastname: Lee
authors.forename: Tiong-Cheng
authors.initials: TC
authors.lastname: Yeo
mesh_terms: D000328:Adult; D000368:Aged; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D015992:Body Mass Index; D015331:Cohort Studies; D003187:Compliance; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis / Q000628:therapy; D017286:Polysomnography; D012307:Risk Factors; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D014463:Ultrasonography