Is there evidence of early vascular disease in patients with obstructive sleep apnoea without known comorbidities? Preliminary findings

Targeting subclinical organ damage in obstructive sleep apnea: a narrative review

Subclinical abnormalities in cardiac and vascular structure reflect the adverse effects triggered by a variety of risk factors on the cardiovascular (CV) system thereby representing an intermediate step in the cardiovascular continuum; such alterations are recognized as reliable markers of increased cardiovascular risk in different clinical settings including obstructive sleep apnea (OSA). The mechanisms underlying subclinical organ damage (OD) in the OSA setting are multifactorial. Hypoxemia and hypercapnia, induced by repeated collapses of upper airways, have been suggested to trigger a cascade of events such as activation of the sympathetic tone, renin-angiotensin-aldosterone system leading to endothelial dysfunction, vasoconstriction, myocardial and vascular remodeling, and hypertension. Furthermore, coexisting non-haemodynamic alterations such as increased oxidative stress, release of inflammatory substances, enhanced lipolysis and insulin resistance have been reported to play a role in the pathogenesis of both cardiac and extra-cardiac OD. In this article we reviewed available evidence on the association between OSA and subclinical cardiac (i.e., left and right ventricular hypertrophy, left atrial dilatation) and extra-cardiac organ damage (i.e., carotid atherosclerosis, arterial stiffness, microvascular retinal changes, and microalbuminuria). This association is apparently stronger for cardiac and carotid subclinical damage than for other markers (i.e., arterial stiffness and retinal changes) and mostly evident in the setting of severe OSA.

The Association Between Obstructive Sleep Apnea and Carotid Intima-Media Thickness: A Systematic Review and Meta-Analysis

Obstructive sleep apnea (OSA) has been suggested as a risk factor for carotid atherosclerosis. The present meta-analysis aimed to evaluate the association between OSA and carotid intima-media thickness (CIMT). Eighteen studies comparing CIMT of patients with OSA versus non-OSA patients were included. Quantitative data synthesis was used to pool weighted standardized difference in means (SMD) of CIMT in a random-effects model. Compared to healthy controls, patients with OSA had a significantly higher CIMT (SMD: 0.881; 95% confidence interval [CI]: 0.647-1.115; P < .001). Due to the great heterogeneity, a subgroup analysis was conducted based on the study design. The pooled SMD of CIMT between patients with OSA and healthy controls were 0.810 (95% CI: 0.676-0.943; P < .001) and 1.008 (95% CI: 0.506-1.510; P < .001) in matched and unmatched group, respectively. Moreover, the correlation of apnea-hypopnea index and CIMT was moderate ( r = .389; 95% CI: 0.315-0.459; P < .001). After adjustment for several major confounders, OSA is an independent risk factor for CIMT. These findings remind clinicians to screen for cardiovascular diseases in patients with OSA.

Neck circumference and early stage atherosclerosis: the cardiometabolic risk in Chinese (CRC) study

Background

Neck circumference (NC) has been previously related to cardiometabolic risk factors. In this study we examined the association between NC and early stage atherosclerosis in Chinese adults.

Methods

The study samples were from a community-based health examination survey in central China. In total 2,318 men and women (18-64 y) were included in the final analyses. Carotid radial pulse wave velocity (crPWV), carotid femoral PWV (cfPWV), carotid artery dorsalis pedis PWV (cdPWV) and NC were measured.

Results

After adjustment for age, sex, lipids, glucose, blood pressure, heart rate, body mass index (BMI), high NC was significantly associated with an increasing trend of cfPWV, cdPWV and crPWV (P = 0.001, 0.049, and 0.038; respectively). In addition, we found significant interaction between hypertension status and NC level in relation to cfPWV, adjusted for age, sex, BMI, fasting glucose, lipids and heart rate(P for interaction = 0.034). The associations between NC and cfPWV were significant (P = 0.02) among those with hypertension, but not significant among those without hypertension.

Conclusions

Our data showed that high NC was associated with an increased risk of early stage atherosclerosis in Chinese adults, independent of other metabolic risk factors. Hypertension might modify the association between NC and cfPWV.

The effect of obstructive sleep apnea syndrome and snoring severity to intima-media thickening of carotid artery

INTRODUCTION

Intima-media thickening (IMT), which is the early finding of carotid artery atherosclerosis, has been shown to be associated with obstructive sleep apnea syndrome (OSAS). In our study, we aimed to assess prospectively the effect of severity of OSAS and snoring on carotid artery IMT.

METHODS

A total of 102 patients who were admitted to sleep laboratory between May 2011 and May 2012 were included in the study. All patients were examined by polysomnography. Common carotid arteries (CCA) and internal carotid arteries (ICA) were evaluated for IMT by carotid Doppler ultrasonography.

RESULTS

The mean age was 45.9 ± 11.1, with 40 (39.2 %) women and 62 (60.8 %) men. Of 88 OSAS patients who had an apnea-hypopnea index (AHI) of >5, 33 (37.5 %) had mild, 20 (22.7 %) had moderate, and 35 (39.8 %) had severe disease. Fourteen patients who had AHI <5 were designated as the habitual snoring group. IMT was detected in 17 (16.7 %) of all patients. In patients with severe OSAS, CCA walls were thicker (p = 0.040) and IMT ratios were higher (p = 0.019) compared to mild/moderate OSAS patients. In patients with IMT, age, AHI, oxygen desaturation index (ODI), and snoring index were higher compared to patients without IMT (p < 0.05).

CONCLUSION

Carotid artery IMT, which is an early finding of atherosclerosis, was found to be highly correlated with OSAS and snoring severity.