• Li-Ching Lee, Maria Consolacion Torres, See-Meng Khoo, Eric Y Chong, Cindy Lau, Yemon Than, Dong-Xia Shi, Anand Kailasam, Kian-Keong Poh, Chi-Hang Lee, and Tiong-Cheng Yeo.
• Cardiac Department, National University Hospital, Singapore, National University Health System, Singapore. leeliching@yahoo.com
• Sleep. 2010 Sep 1;33(9):1173-6.

BackgroundRecent 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.MethodsThis 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.ResultsThe 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).ConclusionsHypertension 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.

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