Obstructive sleep apnea syndrome: a risk factor for Stanford's type B aortic dissection

Obstructive sleep apnea syndrome (OSAS) has been associated with aortic dissection (AD), but the magnitude of this association and its independence from confounders have not yet been established.

A cross-sectional study was performed in 82 patients with Stanford's Type B AD and 116 controls from May 2009 to October 2012. A sleep study was performed in both groups using a modified Berlin questionnaire and polysomnography. Univariate and multivariate analyses were performed to identify factors associated with AD. A third study in controls with OSAS but without AD was performed to prospectively assess the incidence of AD onset during follow-up. Cases and controls were matched for confounding factors.

Cases had significantly higher Berlin scores than controls (75.6% vs. 54.3% high risk, P = 0.002). OSAS frequency was 81.7% among patients and 67.2% among controls (P = 0.024). Patients with Stanford's Type B AD had higher apneas-hypopneas index (17.4 vs. 7.0 events/hr, P = 0.001) and mean 4% oxygen desaturation index (16 vs. 7 events/hr, P = 0.005) and a lower SaO2 during sleep (average 87% vs. 93%, P = 0.005) than controls. In a logistic regression model, OSAS was independently associated with Stanford's Type B AD (odds ratio 1.063, 95% confidence interval: 1.010-1.120; P = 0.020). Two patients developed AD during the prospective study. Both patients had serious OSAS and high Berlin risk, respectively. In addition, patients with coexisting AD and OSAS were significantly younger.

OSAS is highly prevalent and independently associated with Stanford's Type B AD. OSAS comorbidity should be considered in patients with clinically silent AD. Therapeutic strategy for patient with coexisting AD and OSAS such as continuous positive airway pressure and beta blockers needs to be evaluated.