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Carotid Stenosis and Sleep Apnea | Journal Scan
Study Questions:
Is sleep apnea more common in patients with severe carotid artery stenosis?
Methods:
Participants were recruited from a single center, between 2007 and 2012, into a prospective cohort study. Recruitment took place among asymptomatic outpatients with carotid stenosis discovered as part of cardiovascular risk assessment. Patients with a stenosis of <70% were assigned to the mild/moderate group, and those with >70% were assigned to the severe stenosis group. Subjects then underwent echocardiography, magnetic resonance imaging (MRI) of the brain with angiography, as well as an overnight attended sleep study. Patients with previously diagnosed renal failure on dialysis or neurodegenerative diseases were excluded. Those with concomitant heart failure class III or IV, ejection fraction <50%, or resting PO2 <60 mm Hg were excluded. Also, those with symptomatic carotid stenosis (stroke within 6 months), history of stroke, intracranial stenosis, or carotid dissection were excluded.
Results:
A total of 96 patients (mean age 65.9 ± 10.0 years) with asymptomatic carotid stenosis were recruited. Of these, 21 patients had mild/moderate and 75 patients severe carotid stenosis. Patients with severe stenosis were older than those with mild/moderate stenosis (67.2 ± 9.0 years vs. 61.4 ± 11.9 years, p ≤ 0.05). Frequency of arterial hypertension (p ≤ 0.01) and diabetes mellitus (p ≤ 0.05) was higher in the severe stenosis group compared with mild/moderate stenosis. There was no difference in weight, ejection fraction, and presence of coronary artery disease, dyslipidemia, smoking, or alcohol intake.
Overall prevalence of sleep apnea was 68.8%: obstructive sleep apnea (OSA) was present in 41.7% and central sleep apnea (CSA) in 27.1%. Prevalence and severity of sleep apnea increased with degree of stenosis (p ≤ 0.05) because of a rise in CSA (p ≤ 0.01), but not in OSA. Sleep apnea (odds ratio [OR], 3.8; p ≤ 0.03) and arterial hypertension (OR, 4.1; p ≤ 0.05) were associated with stenosis severity, whereas diabetes, smoking, dyslipidemia, body mass index, age, and sex were not. Stenosis severity trended with CSA (p ≤ 0.06), but not OSA. In addition, CSA but not OSA showed a strong association with arterial hypertension (OR, 12.5; p ≤ 0.02) and diabetes (OR, 4.5; p ≤ 0.04).
Conclusions:
The authors concluded that sleep apnea is highly prevalent in asymptomatic carotid stenosis, and is associated with arteriosclerotic disease as well as presence of hypertension and diabetes.
Perspective:
This is the first prospective study to examine the prevalence of sleep apnea and its association with carotid atherosclerotic disease. Intermittent hypoxia observed in OSA and CSA, which results in increased sympathetic activity, is thought to be the mechanistic link between sleep apnea and atherosclerosis. Although OSA is a risk for resistant hypertension, in this study, CSA rather than OSA was associated with hypertension. Treatment of OSA with positive airway pressure has positive effects on arterial biologic processes associated with the development of atherosclerosis, but has not been shown in a prospective manner with CSA. Future studies may also evaluate the impact of carotid revascularization on CSA severity.
Keywords: Sleep Apnea, Central, Sleep Apnea, Obstructive, Sleep Apnea Syndromes, Angiography, Arteriosclerosis, Atherosclerosis, Body Mass Index, Cardiovascular Diseases, Carotid Artery Diseases, Carotid Stenosis, Coronary Artery Disease, Diabetes Mellitus, Dyslipidemias, Echocardiography, Heart Failure, Hypertension, Magnetic Resonance Imaging, Outpatients, Prevalence, Risk Assessment, Risk Factors, Smoking, Cohort Studies, Prospective Studies
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