The incremental role of obstructive sleep apnoea on markers of atherosclerosis in patients with metabolic syndrome

Effects of different treatments on metabolic syndrome in patients with obstructive sleep apnea: a meta-analysis

Background

Obstructive sleep apnea (OSA) and metabolic syndrome (MetS) often coexist, and the causal relationship between them is not yet clear; treatments for OSA include continuous positive airway pressure (CPAP), mandibular advancement device (MAD), surgery, and lifestyle intervention and so on. However, the effects of different treatments on metabolic syndrome in OSA patients are still under debate.

Objectives

Review the effects of different treatments on metabolic syndrome in OSA patients by meta-analysis.

Methods

we searched articles in PubMed, Embase, Cochrane Library, CNKI, CBM, and Wanfang data from database construction to Feb. 2024.RevMan5.4 and Stata software were used to conduct a meta-analysis of 22 articles.

Results

A total of 22 articles were finally included. The results showed that CPAP treatment could reduce the prevalence of metabolic syndrome in OSA patients in randomized controlled trials (RCTs) (RR = 0.82 [95% CI, 0.75 to 0.90]; p < 0.01) and single-arm studies (RR = 0.73 [95% CI, 0.63 to 0.84]; p < 0.01). As for metabolic syndrome components, CPAP treatment reduces blood pressure, fasting glucose (FG), triglycerides (TG), and waist circumference (WC) but can't affect high-density lipoprotein cholesterol (HDL-C) levels. Lifestyle intervention could significantly reduce the prevalence of metabolic syndrome in OSA patients (RR = 0.60 [95% CI, 0.48 to 0.74]; p < 0.01) and can lower blood pressure, fasting glucose, and waist circumference but can't affect the lipid metabolism of OSA patients. Upper airway surgery can only reduce TG levels in OSA patients (MD = -0.74 [95% CI, -1.35 to -0.13]; p = 0.02) and does not affect other components of metabolic syndrome. There is currently no report on the impact of upper airway surgery on the prevalence of metabolic syndrome. No study has reported the effect of MAD on metabolic syndrome in OSA patients.

Conclusion

We confirmed that both CPAP and lifestyle intervention can reduce the prevalence of MetS in OSA patients. CPAP treatment can lower blood pressure, fasting glucose, waist circumference, and triglyceride levels in OSA patients. Lifestyle intervention can lower blood pressure, fasting glucose, and waist circumference in OSA patients. Upper airway surgery can only reduce TG levels in OSA patients.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022326857.

Effect of continuous positive airway pressure on atrial remodeling and diastolic dysfunction of patients with obstructive sleep apnea and metabolic syndrome: a randomized study

OBJECTIVE

The aim of this study was to evaluate the role of obstructive sleep apnea (OSA) treatment on heart remodeling and diastolic dysfunction in patients with metabolic syndrome (MS).

METHODS

This study is a prespecified analysis of a randomized placebo-controlled trial that enrolled patients with a recent diagnosis of MS and moderate-to-severe OSA to undergo continuous positive airway pressure (CPAP) or nasal dilators (placebo) for 6 months. Patients were invited to perform a transthoracic echocardiogram by a single investigator blinded to treatment assignment.

RESULTS

A total of 99 (79% men; mean [SD], age: 48 [9] years; BMI: 33 [4] kg/m² ) completed the study. At follow-up, in the placebo group, patients had a significant increase in atrial diameter: from 39.5 (37.0-43.0) mm to 40.5 (39.0-44.8) mm (p = 0.003). CPAP prevented atrial enlargement: from 40.0 (38.0-44.0) to 40.0 (39.0-45.0) mm (p = 0.194). In patients with diastolic dysfunction at baseline, almost half had diastolic dysfunction reversibility with CPAP (in comparison with only two patients in the placebo group, p = 0.039). In the regression analysis, the chance of diastolic dysfunction reversibility by CPAP was 6.8-fold (95% CI: 1.48-50.26, p = 0.025) compared with placebo.

CONCLUSIONS

In patients with MS and OSA, 6 months of CPAP therapy prevented atrial remodeling and increased the chance of diastolic dysfunction reversibility.

Obstructive sleep apnea and metabolic syndrome

Metabolic syndrome (MS) is a heterogeneous condition associated with increased cardiovascular risk. There is growing evidence from experimental, translational, and clinical investigations that has suggested that obstructive sleep apnea (OSA) is associated with prevalent and incident components of MS and MS itself. The biological plausibility is supportive, primarily related to one of the main features of OSA, namely intermittent hypoxia: increased sympathetic activation with hemodynamic repercussions, increased hepatic glucose output, insulin resistance through adipose tissue inflammation, pancreatic β-cell dysfunction, hyperlipidemia through the worsening of fasting lipid profiles, and the reduced clearance of triglyceride-rich lipoproteins. Although there are multiple related pathways, the clinical evidence relies mainly on cross-sectional data preventing any causality assumptions. The overlapping presence of visceral obesity or other confounders such as medications challenges the ability to understand the independent contribution of OSA on MS. In this review, we revisit the evidence on how OSA/intermittent hypoxia could mediate adverse effects of MS parameters independent of adiposity. Particular attention is devoted to discussing recent evidence from interventional studies. This review describes the research gaps, the challenges in the field, perspectives, and the need for additional high-quality data from interventional studies addressing the impact of not only established but promising therapies for OSA/obesity.

Screening for obstructive sleep apnea before coronary angiography

INTRODUCTION

The prevalence of obstructive sleep apnea (OSA) in patients with suspected coronary heart disease (CHD) is yet to be clarified. This study aimed to investigate the prevalence of OSA before coronary angiography (CAG).

METHODS

We retrospectively evaluated patients with suspected CHD admitted to the Department of Geriatric Cardiology of our hospital between July 2019 and July 2021. OSA was screened using the level III home sleep apnea test before CAG. The prevalence of OSA was then compared between the CHD and non-CHD groups. CHD severity was determined using the Gensini score of CAG results, and OSA severity was graded using the apnea-hypopnea index (AHI).

RESULTS

Among the 327 patients, 211 had CHD. In total, 264 patients were diagnosed with OSA (80.7%) (184 patients, CHD group [87.2%]; 80 patients, non-CHD group [69.0%]). The CHD group had a significantly higher prevalence of OSA (P < 0.01) and higher AHI (CHD group 18.76 ± 14.94, non-CHD group 11.56 ± 10.67, P < 0.01). The Gensini score was positively correlated with OSA severity in patients with CHD, and AHI ≥ 20 was a risk factor for CHD (odds ratio: 1.961, 95% confidence interval: 1.065-3.608, P < 0.05).

CONCLUSION

OSA screening before CAG revealed a higher prevalence in CHD patients than in non-CHD patients. The degree of coronary artery obstruction is positively correlated with AHI, and AHI ≥ 20 is a risk factor for CHD. Therefore, attention should be paid to OSA screening and management before CAG in patients with suspected CHD.

Profiles of transcriptome and metabolic pathways after hypobaric hypoxia exposure

Background

Hypoxia is a risk factor for non-alcoholic fatty liver diseases, leading to permanent imbalance of liver lipid homeostasis and steatohepatitis. However, a detailed understanding of the metabolic genes and pathways involved remains elusive.

Methods

In vivo experiments were designed to analyze body weight and lipid metabolism changes of rats under hypoxia. After this, we combined microarray analysis and gene overexpression experiments to validate the core mechanisms involved in the response to hypoxia.

Results

The hypobaric hypoxia treated rats exhibited significantly increased serum triglycerides (TG) (p < 0.05), despite no significant changes in serum alanine aminotransferase (ALT) and blood glucose (BG) were observed. In addition, serum high-density lipoprotein cholesterol (HDL-C) greatly increased after 3 days and then returned to normal level at 30 days. Interestingly, serum low-density lipoprotein cholesterol (LDL-C) showed an opposite pattern. Transcriptome analysis, qRT-PCR, ICC revealed that the genes PPARA, ANGPTL4, CPT-I, ACC and LPL play a crucial role in response to hypobaric hypoxia. IPA pathway analysis further confirmed that PPARA-mediated regulation of ANGPTL4 participated in TG clearance and lipoprotein metabolism. Finally, the PPARA-ANGPTL4 pathway was validated in rats and HL 7702 cells treated with Fenofibrate, a PPARA specific agonist.

Conclusions

Our study showed this pathway plays an important role on lipid metabolism caused by hypobaric hypoxia and the potential target genes associated with oxygen-dependent lipid homeostasis in the liver.

Association of the Coexistence of Somnipathy and Diabetes With the Risks of Cardiovascular Disease Events, Stroke, and All‐Cause Mortality: A Systematic Review and Meta‐analysis

Background

Somnipathy and diabetes are independently associated with an increased risk of cardiovascular disease (CVD). However, whether a combination of both conditions is associated with a higher risk of CVD events remains uncertain. Therefore, the aim of this meta‐analysis was to clarify this association.

Methods and Results

We searched MEDLINE, Web of Science, EMBASE, ClinicalTrials.gov , and the Cochrane Central Register for Controlled Trials. We included randomized controlled trials, nonrandomized trials, and prospective observational cohort studies that assessed the combined effect of diabetes and comorbid somnipathy on CVD risk and mortality for at least 1 year. Outcomes included CVD, coronary heart disease, stroke, and all‐cause mortality. Twelve studies involving 582 267 participants were included in the meta‐analysis. Patients with somnipathy and comorbid diabetes exhibited increased risks of CVD, coronary heart disease, stroke, and all‐cause mortality (risk ratio [RR], 1.27 [95% CI, 1.12–1.45], P <0.0001; RR, 1.40 [95% CI, 1.21–1.62], P <0.0001; RR, 1.28 [95% CI, 1.08–1.52], P =0.004, and RR, 1.56 [95% CI, 1.26–1.94], P <0.0001, respectively).

Conclusions

The coexistence of somnipathy and diabetes is associated with higher risks of CVD, coronary heart disease, stroke, and mortality than somnipathy or diabetes alone. Resolving sleep problems in patients with diabetes may reduce the risks of CVD, stroke, and mortality.

Registration Information

https://www.crd.york.ac.uk/prospero/ . Identifier: PROSPERO CRD42021274566.

Effects of CPAP on Metabolic Syndrome in Patients With OSA: A Randomized Trial

BACKGROUND

OSA is associated with metabolic syndrome (MS), but it is unclear whether OSA treatment with CPAP can revert MS.

RESEARCH QUESTION

Does OSA treatment with CPAP per se have effects on the MS reversibility and the associated metabolic, adiposity and vascular parameters?

STUDY DESIGN AND METHODS

The TREATOSA-MS trial is a randomized placebo-controlled trial that enrolled adult patients with a recent diagnosis of MS and moderate or severe OSA (apnea-hypopnea index [AHI], ≥ 15 events/h) to undergo therapeutic CPAP or nasal dilator strips (placebo group) for 6 months. Before and after each intervention, we measured anthropometric variables, BP, glucose, and lipid profile. To control potential-related mechanisms and consequences, we also measured adiposity biomarkers (leptin and adiponectin), body composition, food intake, physical activity, subcutaneous and abdominal fat (visceral and hepatic fat), and endothelial function.

RESULTS

One hundred patients (79% men; mean age, 48 ± 9 years; BMI, 33 ± 4 kg/m²; AHI, 58 ± 29 events/h) completed the study (n = 50 per group). The mean CPAP adherence was 5.5 ± 1.5 h/night. After 6 months, most patients with OSA randomized to CPAP retained the MS diagnosis, but the rate of MS reversibility was higher than observed in the placebo group (18% vs 4%; OR, 5.27; 95% CI, 1.27-35.86; P = .04). In the secondary analysis, CPAP did not promote significant reductions in the individual components of MS, weight, hepatic steatosis, lipid profile, adiponectin, and leptin, but did promote a very modest reduction in visceral fat and improved endothelial function (all analyses were adjusted for baseline values).

INTERPRETATION

Despite the higher rate of MS reversibility after CPAP therapy as compared with placebo, most patients retained this diagnosis. The lack of significant or relevant effects on adiposity biomarkers and depots supports the modest role of OSA in modulating MS.

TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT02295202; URL: www.

CLINICALTRIALS

gov.

Obstructive sleep apnea and cardiovascular comorbidity: common pathophysiological mechanisms to cardiovascular disease

Obstructive sleep apnea (OSA) is associated with many cardiovascular and metabolic diseases. Sleep apnea causes intermittent hypoxemia, chest pressure fluctuations and a reaction from the cerebral cortex in the form of a short awakening during sleep (EEG-activation). The consequences of pathological pathways are studied in experimental models involving cell cultures, animals, and healthy volunteers. At present, the negative impact of intermittent hypoxemia on a variety of pathophysiological disorders of the heart and blood vessels (vascular tone fluctuations, thickening of the intimamedia complex in the vascular wall, direct damaging effect on the myocardium) has a great evidence base. Two other pathological components of OSA (pressure fluctuations and EEG-activation) can also affect cardiovascular system, mainly affecting the increase in blood pressure and changing cardiac hemodynamics. Although these reactions are considered separately in the review, with the development of sleep apnea they occur sequentially and are closely interrelated. As a result, these pathological pathways trigger further pathophysiological mechanisms acting on the heart and blood vessels. It is known that these include excessive sympathetic activation, inflammation, oxidative stress and metabolic dysregulation. In many respects being links of one process, these mechanisms can trigger damage to the vascular wall, contributing to the formation of atherosclerotic lesions. The accumulated data with varying degrees of reliability confirm the participation of OSA through these processes in the formation of cardiovascular disorders. There are factors limiting direct evidence of this interaction (sleep deprivation, causing similar changes, as well as the inability to share the contribution of other risk factors for cardiovascular diseases, in particular arterial hypertension, obesity, which are often associated with OSA). It is necessary to continue the study of processes that implement the pathological effect of OSA on the cardiovascular system.

Mirabegron Ameliorated Atherosclerosis of ApoE-/- Mice in Chronic Intermittent Hypoxia but Not in Normoxia

PURPOSE

It has been established that obstructive sleep apnea (OSA) is an independent risk factor for atherosclerosis. Chronic intermittent hypoxia (CIH) activates sympathoadrenal system and upregulates β3 adrenergic receptor (β3 AR). However, the effect of selective β3 AR agonist mirabegron in CIH-induced atherosclerosis remains unknown.

METHODS

We generated a CIH-induced atherosclerosis model through exposing ApoE^-/- mice to CIH (8 h per day, cyclic inspiratory oxygen fraction 5-21%, 60-s cycle) for 6 weeks after 4-week high-fat dieting and investigated the effects of mirabegron, a selective β3 AR agonist, on CIH-induced atherosclerosis. The coronary endarterectomy (CE) specimens from coronary artery disease patients with OSA and without OSA were collected.

RESULTS

The expression of β3 AR was significantly elevated in CIH-induced atherosclerosis model. Furthermore, treatment with mirabegron (10mg/kg per day by oral administration for 6 weeks) ameliorated atherosclerosis in ApoE^-/- mice in CIH but not in normoxia. Mechanistically, mirabegron activated β3 AR and ameliorated intraplaque oxidative stress by suppressing p22phox expression and reactive oxygen species (ROS) level. In addition, in human CE specimens, β3 AR was also upregulated associated with increased p22phox expression and ROS level both in the lumen and in the plaque of coronary artery in OSA subjects.

CONCLUSION

This study first demonstrated that mirabegron impeded the progression of CIH-induced atherosclerosis, at least in part, via β3 AR-mediated oxidative stress, suggesting a promising therapeutic strategy for protecting against atherosclerosis induced by CIH.

Telemedicine for Continuous Positive Airway Pressure in Sleep Apnea. A Randomized, Controlled Study

Rationale: Continuous positive airway pressure (CPAP) is the standard treatment for the obstructive sleep apnea syndrome (OSAS), but long-term adherence remains a challenge. In a pilot study, we observed that telemedicine combined with telemetrically triggered interventions was associated with improved CPAP adherence in the first month of treatment.Objectives: In the current randomized, controlled phase III trial, we aimed to collect pivotal data for the use of telemedicine in CPAP treatment of patients with OSAS.Methods: Symptomatic patients with OSAS were randomized to a telemedicine or control arm and initiated CPAP treatment. Phone calls were triggered in the telemedicine group during the first month of treatment upon either poor use or excessive mask leakage. Patients were followed for 6 months. Measures of CPAP use at 6 months were the main study endpoints.Results: Among 240 patients enrolled, 71 (30%) discontinued CPAP treatment over the course of the study. The primary outcome measure, the proportion of nights with CPAP use greater than 1 hour, was not statistically different in the telemedicine group (92.0%) versus the control group (88.2%) (P = 0.565). The daily hours of CPAP use at 6 months also did not differ significantly between the telemedicine group (5.6 h) and the control group (4.8 h) (P = 0.663). However, in a post hoc analysis, telemedicine led to increased device use in a subgroup of patients with a mild form of disease (5.6 h vs. 3.4 h; P = 0.026). The telemedicine-based intervention had a positive impact on sleep-related quality of life as measured with the Quebec Sleep Questionnaire (5.55 vs. 5.49 at 1 mo [P = 0.020]; 5.61 vs. 5.46 at 6 mo [P = 0.013]).Conclusions: A telemetrically triggered intervention in the first month of treatment did not improve CPAP use in the study population overall, but it had positive effects in patients with a mild form of OSAS and led to an improvement in sleep-related quality of life.Clinical trial registered with www.clinicaltrials.gov (NCT01715194).

Long-term variations of arterial stiffness in patients with obesity and obstructive sleep apnea treated with continuous positive airway pressure

BACKGROUND

Obstructive sleep apnea (OSA) is associated with cardiovascular co-morbidities and mortality. Arterial stiffness is an independent predictor of cardiovascular risk and mortality, and is influenced by the presence of OSA and related comorbidities. There is a paucity of data regarding long-term evolution of arterial stiffness in CPAP-treated OSA patients. We aimed to prospectively study long term PWV variations and determinants of PWV deterioration.

METHODS

In a prospective obese OSA cohort, at time of diagnosis and after several years of follow-up we collected arterial stiffness measured by carotid-femoral pulse wave velocity (PWV), clinical and metabolic parameters, and CPAP adherence. Univariate and multivariate analyses were performed in order to determine contributing factors.

RESULTS

Seventy two OSA patients (men: 52.8%, median age: 55.8 years and median BMI of 38.5 kg/m2) with a prevalence of hypertension: 58.3%, type 2 diabetes: 20.8%, hypercholesterolemia: 33.3%, current or past smoking: 59.7%, were evaluated after a median follow-up of 7.4 [5.8; 8.3] years. Over the period of follow-up, the median increase in PWV was 1.34 [0.10; 2.37] m/s. In multivariate analysis, the increase in PWV was associated with older age (10 extra years was associated with a 5.24 [1.35; 9.12] % increase in PWV) and hypertension (a significant increase in PWV of 8.24 [1.02; 15.57] %). No impact of CPAP adherence on PWV evolution was found.

CONCLUSION

PWV progression in CPAP-treated OSA patients is mainly related to pre-existing cardio-metabolic comorbidities and not influenced by CPAP adherence. In this high cardiovascular risk population, it is crucial to associated weight management and exercise with CPAP treatment.

Potential Role of mRNAs and LncRNAs in Chronic Intermittent Hypoxia Exposure-Aggravated Atherosclerosis

Atherosclerosis is the pathological basis of cardiovascular disease. Obstructive sleep apnea (OSA) aggravates atherosclerosis, and chronic intermittent hypoxia (CIH) as a prominent feature of OSA plays an important role during the process of atherosclerosis. The mechanisms of CIH in the development of atherosclerosis remain unclear. In the current study, we used microarray to investigate differentially expressed mRNAs and long non-coding RNAs (lncRNAs) in aorta from five groups of ApoE^–/– mice fed with a high-fat diet and exposed to various conditions: normoxia for 8 weeks, CIH for 8 weeks, normoxia for 12 weeks, CIH for 12 weeks, or CIH for 8 weeks followed by normoxia for 4 weeks. Selected transcripts were validated in aorta tissues and RT-qPCR analysis showed correlation with the microarray data. Gene Ontology analysis and pathway enrichment analysis were performed to explore the mRNA function. Bioinformatic analysis indicated that short-term CIH induced up-regulated mRNAs involved in inflammatory response. Pathway enrichment analysis of lncRNA co-localized mRNAs and lncRNA co-expressed mRNAs were performed to explore lncRNA functions. The up-regulated mRNAs, lncRNA co-localized mRNAs and lncRNA co-expressed mRNAs were significantly associated with protein processing in endoplasmic reticulum pathway in atherosclerotic vascular tissue with long-term CIH exposure, suggesting that differentially expressed mRNAs and lncRNAs play important roles in this pathway. Moreover, a mRNA-lncRNA co-expression network with 380 lncRNAs, 508 mRNAs and 3238 relationships was constructed based on the correlation analysis between the differentially expressed mRNAs and lncRNAs. In summary, our study provided a systematic perspective on the potential function of mRNAs and lncRNAs in CIH-aggravated atherosclerosis, and may provide novel molecular candidates for future investigation on atherosclerosis exposed to CIH.

Obstructive sleep apnea and dyslipidemia: from animal models to clinical evidence

Lipid metabolism deregulation constitutes the pathogenic basis for the development of atherosclerosis and justifies a high incidence of cardiovascular-related morbidity and mortality. Some data suggest that dyslipidemia may be associated with sleep-disordered breathing, mainly obstructive sleep apnea (OSA), due to alterations in fundamental biochemical processes, such as intermittent hypoxia (IH). The aim of this systematic review was to identify and critically evaluate the current evidence supporting the existence of a possible relationship between OSA and alterations in lipid metabolism. Much evidence shows that, during the fasting state, OSA and IH increase lipid delivery from the adipose tissue to the liver through an up-regulation of the sterol regulatory element-binding protein-1 and stearoyl-CoA desaturase-1, increasing the synthesis of cholesterol esters and triglycerides. In the postprandial state, lipoprotein clearance is delayed due to lower lipoprotein lipase activity, probably secondary to IH-up-regulation of angiopoietin-like protein 4 and decreased activity of the peroxisome proliferator-activated receptor alpha. Moreover, oxidative stress can generate dysfunctional oxidized lipids and reduce the capacity of high-density lipoproteins (HDL) to prevent low-density lipoprotein (LDL) oxidation. In the clinical field, several observational studies and a meta-regression analysis support the existence of a link between OSA and dyslipidemia. Although there is evidence of improved lipid profile after apnea-hypopnea suppression with continuous positive airway pressure (CPAP), the majority of the data come from observational studies. In contrast, randomized controlled trials evaluating the effects of CPAP on lipid metabolism present inconclusive results and two meta-analyses provide contradictory evidence.

Point-of-Care Ultrasound for Obstructive Sleep Apnea Screening: Are We There Yet? A Systematic Review and Meta-analysis

BACKGROUND

Perioperative diagnosis of obstructive sleep apnea (OSA) has important resource implications as screening questionnaires are overly sensitive, and sleep studies are expensive and time-consuming. Ultrasound (US) is a portable, noninvasive tool potentially useful for airway evaluation and OSA screening in the perioperative period. The objective of this systematic review was to evaluate the correlation of surface US with OSA diagnosis and to determine whether a point-of-care ultrasound (PoCUS) for OSA screening may help with improved screening in perioperative period.

METHODS

A search of all electronic databases including Medline, Embase, and Cochrane Database of Systematic Reviews was conducted from database inception to September 2017. Inclusion criteria were observational cohort studies and randomized controlled trials of known or suspected OSA patients undergoing surface US assessment. Article screening, data extraction, and summarization were conducted by 2 independent reviewers with ability to resolve conflict with supervising authors. Diagnostic properties and association between US parameters (index test) and OSA diagnosis using sleep study (reference standard) were evaluated. The US parameters were divided into airway and nonairway parameters. A random-effects meta-analysis was planned, wherever applicable.

RESULTS

Of the initial 3865 screened articles, 21 studies (7 airway and 14 nonairway) evaluating 3339 patients were included. Majority of studies were conducted in the general population (49%), respirology (23%), and sleep clinics (12%). No study evaluated the use of US for OSA in perioperative setting. Majority of included studies had low risk of bias for reference standard and flow and timing. Airway US parameters having moderate-good correlation with moderate-severe OSA were distance between lingual arteries (DLAs > 30 mm; sensitivity, 0.67; specificity, 0.59; 1 study/66 patients); mean resting tongue thickness (>60 mm; sensitivity, 0.85; specificity, 0.59; 1 study/66 patients); tongue base thickness during Muller maneuver (MM; sensitivity, 0.59; specificity, 0.78; 1 study/66 patients); and a combination of neck circumference and retropalatal (RP) diameter shortening during MM (sensitivity, 1.0; specificity, 0.65; 1 study/104 patients). Nonairway US parameters having a low-moderate correlation with moderate-severe OSA were carotid intimal thickness (pooled correlation coefficient, 0.444; 95% confidence interval [CI], 0.320-0.553; P value = .000, 8 studies/727 patients) and plaque presence (sensitivity, 0.24-0.75; specificity, 0.13-1.0; 4 studies/1183 patients).

CONCLUSIONS

We found that a number of airway and nonairway parameters were identified with moderate to good correlation with OSA diagnosis in the general population. In future studies, it remains to be seen whether PoCUS screening for a combination of these parameters can address the pitfalls of OSA screening questionnaires.

Cross-Sectional Study of Arterial Stiffness in Adolescents with Down Syndrome

OBJECTIVES

To test whether youth with Down syndrome have aortic stiffness indices, as measured by pulse wave velocity (PWV), that differ from youth without Down syndrome and to compare reference-based age-adjusted (age-PWV-Z) and height-adjusted (Ht-PWV-Z) in youth with and without Down syndrome.

STUDY DESIGN

Cross-sectional study of PWV in 129 adolescents with Down syndrome and 97 youth of comparable age, sex, race/ethnicity, and body mass index (BMI). PWV, age-PWV-Z, and Ht-PWV-Z were compared. Regression models were developed to test for associations with PWV.

RESULTS

Youth with Down syndrome and controls were comparable in BMI-Z (1.4 [-1.5 to 2.8] vs 1.2 [-2.0 to 2.8], P = .57) but not Ht-Z (-2.3 [-4.7 to 0.8] vs 0.4 [-2.0 to 2.6], P < .0001). PWV (m/s, 5.0 [3.1-7.9] vs 5.0 [3.6-8.0], P = .5) and mean arterial pressure (MAP, mm Hg) (78 [61-102] vs 74 [64-97], P = .09) were not different between groups. In adjusted analyses confined to Down syndrome, PWV was associated only with BMI, but not age, black race, or MAP (R2 = 0.11). In contrast, BMI, age, black race, and MAP were all positively associated with and better explained PWV in controls (R2 = 0.50). PWV was not associated with height in youth with or without Down syndrome. Although age-PWV-Z was not different in Down syndrome (-0.36 [-2.93 to 3.49]) vs -0.15 [-2.32 to 3.22]), Ht-PWV-Z was greater in Down syndrome (0.32 [-2.28 to 4.07] vs -0.08 [-2.64 to 2.64], P = .002), and Ht-PWV-Z was greater than age-PWV-Z in Down syndrome (P < .0001).

CONCLUSIONS

The lack of relationship of PWV, an independent predictor of adult cardiovascular events, with its traditional determinants including MAP suggests Down syndrome-specific phenomena may alter such relationships in this population. In youth with Down syndrome, Ht-adjusted PWV may overestimate aortic stiffness.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT01821300.

Reported obstructive sleep apnea does not diminish the cardiometabolic health benefits from a comprehensive lifestyle intervention program

Obstructive sleep apnea (OSA) commonly coexists with the metabolic syndrome, a condition for which behavioral changes are often prescribed. Whether OSA diminishes the cardiometabolic health benefits from lifestyle interventions remains unclear. We evaluated 278 consecutive metabolic syndrome participants enrolled in a 12-week comprehensive lifestyle intervention program. The changes in blood pressure (BP), along with other metabolic health parameters, from baseline to follow-up were compared between those with and without OSA. Mean age was 52.4 ± 10.9 years and 37% were male. At enrollment, mean body mass index (BMI) was 38.2 ± 7.7 kg/m² . OSA was reported in 126 of 269 final participants (47%). At baseline, participants with reported OSA were more likely to be male, older, have a higher BMI, waist and neck size (all P < 0.05). At program completion, participants with (-5.8 ± 16.1/-3.0 ± 10.0 mm Hg) and without OSA (-4.7 ± 13.1/-3.3 ± 8.2 mm Hg) had significant reductions in systolic and diastolic BP as well as BMI, fasting glucose, and triglyceride levels. There were no significant differences in the absolute or percentage changes in BP or other metabolic parameters between groups. Our findings support that patients with the metabolic syndrome can derive substantial health benefits, including reductions in BP, by a lifestyle intervention program regardless of the presence of OSA.

Sleep apnea and type 2 diabetes

The aim of the present review was to clarify the association between obstructive sleep apnea (OSA) and type 2 diabetes, and discuss the therapeutic role of continuous positive airway pressure (CPAP) in type 2 diabetes. OSA patients are more likely than non-OSA populations to develop type 2 diabetes, while more than half of type 2 diabetes patients suffer from OSA. Similar to Western countries, in the East Asian population, the association between these two disorders has also been reported. CPAP is the primary treatment for OSA, but the effect of CPAP on comorbid diabetes has not been established. CPAP improved glucose metabolism determined by the oral glucose tolerance test in OSA patients, and several studies have shown that CPAP improves insulin resistance, particularly in obese populations undergoing long-term CPAP. Diabetes is associated with other sleep-related manifestations as well, such as snoring and excessive daytime sleepiness. Snoring is associated with the development of diabetes, and excessive daytime sleepiness appears to modify insulin resistance. Well-designed studies are required to clarify the therapeutic effect of CPAP on diabetes. As both diabetes and OSA lead to cardiovascular disease, clinicians and healthcare professionals should be aware of the association between diabetes and OSA, and should take CPAP and health-related behaviors into consideration when treating patients with diabetes and/or OSA.

Gender differences of aortic wave reflection and influence of menopause on central blood pressure in patients with arterial hypertension

Background

Evidences suggest that central hemodynamics indexes are independent predictors of future cardiovascular events and all-cause mortality. Multiple factors have been pointed to have potential influence on central aortic function: height, heart rate, left ventricular ejection duration and blood pressure level. Data related to the influence of gender and postmenopausal status on aortic waveform reflection is scarce. We aim to evaluate the impact of gender and menopause on central blood pressure of hypertensive patients.

Methods

In a cross sectional study 122 hypertensive patients (52 men and 70 women) were studied. Hypertension was defined as blood pressure (BP) levels ≥140/90 mmHg or use of antihypertensive drugs. Central arterial pressure, augmentation index (AIx) and augmentation index normalized to 75 bpm (AIx75) were obtained using applanation tonometry. Menopause and postmenopause history were accessed by a direct series of questions. Postmenopause was defined as at least one year since last menstruation. Patients were paired by age, gender and menopausal status, and the data were compared considering gender and menopausal status.

Results

Height and weight were significantly lower in women than in men at the same age. Conversely, AIx (32.7 ± 9.8% vs. 20.1 ± 11.7%, p < 0.01), AIx75 (29.6 ± 6.7% vs. 18.3 ± 9.4%, p < 0.01) and central systolic blood pressure (136 ± 30 vs. 125 ± 23 mmHg, p = 0.03) were higher in women than men. The menopausal women (mean age of menopause = 48 years) had the worst indexes of aortic wave reflection, compared to men at the same age and younger women.

Conclusion

Hypertensive women had both higher reflected aortic pressure waveform and central blood pressure indexes than hypertensive men, and these findings were worsened by the menopausal status.

Diet associated with exercise improves baroreflex control of sympathetic nerve activity in metabolic syndrome and sleep apnea patients

PURPOSE

We tested the hypothesis that (i) diet associated with exercise would improve arterial baroreflex (ABR) control in metabolic syndrome (MetS) patients with and without obstructive sleep apnea (OSA) and (ii) the effects of this intervention would be more pronounced in patients with OSA.

METHODS

Forty-six MetS patients without (noOSA) and with OSA (apnea-hypopnea index, AHI > 15 events/h) were allocated to no treatment (control, C) or hypocaloric diet (- 500 kcal/day) associated with exercise (40 min, bicycle exercise, 3 times/week) for 4 months (treatment, T), resulting in four groups: noOSA-C (n = 10), OSA-C (n = 12), noOSA-T (n = 13), and OSA-T (n = 11). Muscle sympathetic nerve activity (MSNA), beat-to-beat BP, and spontaneous arterial baroreflex function of MSNA (ABR_MSNA, gain and time delay) were assessed at study entry and end.

RESULTS

No significant changes occurred in C groups. In contrast, treatment in both patients with and without OSA led to a significant decrease in weight (P < 0.05) and the number of MetS factors (P = 0.03). AHI declined only in the OSA-T group (31 ± 5 to 17 ± 4 events/h, P < 0.05). Systolic BP decreased in both treatment groups, and diastolic BP decreased significantly only in the noOSA-T group. Treatment decreased MSNA in both groups. Compared with baseline, ABR_MSNA gain increased in both OSA-T (13 ± 1 vs. 24 ± 2 a.u./mmHg, P = 0.01) and noOSA-T (27 ± 3 vs. 37 ± 3 a.u./mmHg, P = 0.03) groups. The time delay of ABR_MSNA was reduced only in the OSA-T group (4.1 ± 0.2 s vs. 2.8 ± 0.3 s, P = 0.04).

CONCLUSIONS

Diet associated with exercise improves baroreflex control of sympathetic nerve activity and MetS components in patients with MetS regardless of OSA.

Obstructive sleep apnea and effects of continuous positive airway pressure on triglyceride-rich lipoprotein metabolism

This study aimed to explore lipoprotein metabolism in obstructive sleep apnea (OSA) and the effects of continuous positive airway pressure (CPAP). We studied 15 men with severe OSA [apnea-hypopnea index (AHI) ≥30 events/hour] and 12 age-, BMI-, and waist circumference-matched volunteers without OSA (AHI <5 events/hour). Carotid intima-media thickness (CIMT) was determined by a blind examiner. After 12 h fasting, a triglyceride-rich chylomicron-like emulsion, labeled with [¹⁴C]cholesteryl oleate and [³H]triolein, was injected intravenously followed by blood sample collection at preestablished times. Fractional clearance rate (FCR) of the radiolabeled lipids was estimated by compartmental analysis of radioisotope decay curves. Compared with controls, patients with OSA showed a significant delay in both cholesteryl ester FCR (0.0126 ± 0.0187 vs. 0.0015 ± 0.0025 min^-1; P = 0.0313) and triglycerides FCR (0.0334 ± 0.0390 vs. 0.0051 ± 0.0074 min^-1; P = 0.0001). CIMT was higher in the OSA group: 620 ± 17 vs. 725 ± 29 µm; P = 0.004. Cholesteryl ester FCRs were inversely related to total sleep time <90% (r = -0.463; P = 0.029) and CIMT (r = -0.601; P = 0.022). The triglyceride FCR was inversely correlated with AHI (r = -0.537; P = 0.04). In a subgroup of patients treated with CPAP for 3 months (n = 7), triglyceride FCR increased 5-fold (P = 0.025), but the cholesteryl ester FCR was unchanged. In conclusion, severe OSA decreased lipolysis of triglyceride-rich lipoproteins and delayed removal of remnants. CPAP treatment may be effective to restore the lipolysis rates.

[Sleep apneas, metabolic syndrome and cardiovascular risk: Data from the Pays de la Loire sleep cohort]

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a prevalent disease characterized by recurrent episodes of partial or complete obstruction of upper airway during sleep. Untreated moderate to severe OSAHS is recognized as a cardiovascular (CV) risk factor. Data from the Pays de la Loire sleep cohort and other clinic- or population-based cohorts demonstrate a strong association between OSAHS and the different components of the metabolic syndrome including systemic hypertension, diabetes and impaired lipid metabolism. Beside sleep-disordered breathing severity, these factors contribute to increase the risk of CV events in OSAHS patients. Continuous positive airway pressure (CPAP) therapy of OSAHS is associated with a modest but clinically significant blood pressure reduction. Conversely, there is no clear evidence in support of a metabolic impact of CPAP in OSAHS patients. Considering the multifactorial pathophysiology of CV risk in OSAHS patients and the beneficial impact of various lifestyle and pharmacologic interventions on blood pressure and metabolic dysfunction, combined modality therapy is a promising strategy to improve CV outcomes in individuals with OSAHS.

The role of increased glucose on neurovascular dysfunction in patients with the metabolic syndrome

Metabolic syndrome (MetS) causes autonomic alteration and vascular dysfunction. The authors investigated whether impaired fasting glucose (IFG) is the main cause of vascular dysfunction via elevated sympathetic tone in nondiabetic patients with MetS. Pulse wave velocity, muscle sympathetic nerve activity (MSNA), and forearm vascular resistance was measured in patients with MetS divided according to fasting glucose levels: (1) MetS+IFG (blood glucose ≥100 mg/dL) and (2) MetS-IFG (<100 mg/dL) compared with healthy controls. Patients with MetS+IFG had higher pulse wave velocity than patients with MetS-IFG and controls (median 8.0 [interquartile range, 7.2-8.6], 7.3 [interquartile range, 6.9-7.9], and 6.9 [interquartile range, 6.6-7.2] m/s, P=.001). Patients with MetS+IFG had higher MSNA than patients with MetS-IFG and controls, and patients with MetS-IFG had higher MSNA than controls (31±1, 26±1, and 19±1 bursts per minute; P<.001). Patients with MetS+IFG were similar to patients with MetS-IFG but had higher forearm vascular resistance than controls (P=.008). IFG was the only predictor variable of MSNA. MSNA was associated with pulse wave velocity (R=.39, P=.002) and forearm vascular resistance (R=.30, P=.034). In patients with MetS, increased plasma glucose levels leads to an adrenergic burden that can explain vascular dysfunction.

Impact of High Risk for Obstructive Sleep Apnea on Survival after Acute Coronary Syndrome: Insights from the ERICO Registry

Background

Obstructive sleep apnea (OSA) is a very often clinical condition that can be associated with high mortality risk, particularly in coronary heart disease (CHD). The diagnosis of OSA is not always accessible via the gold-standard method polysomnography.

Objective

To evaluate long-term influence of the high risk for OSA on fatal and non-fatal outcomes after acute coronary syndrome (ACS) in the Acute Coronary Syndrome Registry Strategy (ERICO) Study using the Berlin questionnaire as a surrogate.

Methods

Berlin questionnaire, a screening questionnaire for OSA, was applied in 639 cases of ACS 30 days after the index event. Cox regression proportional-hazards model was used to calculate the hazard ratio (HR) of all-cause, cardiovascular and CHD (myocardial infarction) mortality, as well as, the combined endpoint of fatal or recurrent non-fatal CHD.

Results

The high-risk group for OSA had higher frequencies of previous personal/family history of CHD and diabetes, in addition to a poorer event-free survival, as compared to the low-risk group (p-log-rank=0.03). The HR for fatal or recurrent non-fatal CHD was 4.26 (95% confidence interval, 1.18 - 15.36) in patients at high risk for OSA compared to those at low risk for OSA after a 2.6-year mean follow-up.

Conclusions

Using Berlin questionnaire, we were able to identify high risk for OSA as an independent predictor of non-fatal reinfarction or CHD mortality in post-ACS individuals in a long-term follow-up.

Association between obstructive sleep apnea severity and endothelial dysfunction in patients with type 2 diabetes

Background

Obstructive sleep apnea (OSA) and type 2 diabetes (T2D) are associated with endothelial dysfunction a main predictor of late cardiovascular (CV) events. Despite the high prevalence of OSA in patients with T2D, the impact of OSA severity on endothelial function has not been clearly elucidated. The aim of this cross-sectional study was to determine whether increasing OSA severity is associated with poorer endothelial function in patients with T2D.

Methods

140 patients with T2D and no overt CV disease underwent polysomnography, peripheral arterial tonometry, clinic blood pressure (BP) measurement, biological assessment for CV risk factors, daytime sleepiness and health related quality of life (HRQL) questionnaires. The following commonly used cut-offs for apnea-hypopnea index (AHI) were used to define 3 categories of disease severity: AHI < 15 (no OSA or mild OSA), 15 ≤ AHI < 30 (moderate OSA), and AHI ≥ 30 (severe OSA). The primary outcome was the reactive hyperemia index (RHI), a validated assessment of endothelial function.

Results

21.4% of patients had moderate OSA and 47.6% had severe OSA. Increasing OSA severity and nocturnal hypoxemia were not associated with a significant decrease in RHI. Endothelial dysfunction (RHI < 1.67) was found in 47.1, 44.4 and 39.2% of patients with no OSA or mild OSA, moderate OSA and severe OSA, respectively (p = 0.76). After adjustment for confounders including body mass index, increasing OSA severity was associated with higher systolic BP (p = 0.03), lower circulating levels of adiponectin (p = 0.0009), higher levels of sP-selectin (p = 0.03), lower scores in 3 domains of HRQL including energy/vitality (p = 0.02), role functioning (p = 0.01), and social functioning (p = 0.04).

Conclusions

Moderate to severe OSA is very common but has no impact on digital micro-vascular endothelial function in patients with T2D.

[Therapeutic alternatives to continuous positive airway pressure for obstructive sleep apnea-hypopnea syndrome]

Oral appliance therapy (OAT) is the main therapeutic alternative to continuous positive airway pressure (CPAP). OAT has been recommended as an appropriate first-line treatment option for moderate obstructive sleep apnea-hypopnea syndrome (OSAHS) in patients without severe cardiovascular comorbidity. The lower efficacy of OAT in reducing sleep-disordered breathing could be offset by a higher compliance relative to CPAP, resulting in similar health outcomes in terms of sleepiness, neurobehavioral functioning, quality of life and blood pressure. Electrical stimulation of the hypoglossal nerve is a promising treatment approach for moderate to severe OSAHS. Avoiding the supine position during sleep and reducing the overnight rostral fluid shift from the legs to the neck can also achieve a partial improvement of sleep-disordered breathing. There are currently no medications to treat OSAHS effectively. At least fifty percent of OSAHS patients are affected by central obesity and related metabolic disorders. To date, there is no evidence that treating OSAHS may improve comorbid metabolic disorders. Weight-loss intervention is a central component of the strategies used to improve the cardiovascular risk-factor profile in patients with OSAHS and obesity.

Derived Arterial Stiffness is Increased in Patients with Obstructive Sleep Apnea and Periodic Limb Movements during Sleep

STUDY OBJECTIVES

Both periodic limb movements during sleep (PLMS) and obstructive sleep apnea (OSA) have been associated with increased risk of cardiovascular disease (CVD). OSA has also been linked to increased large arterial stiffness, which is considered an independent risk factor for CVD. We utilized a previously validated index of large artery stiffness (SIDVP) derived from the digital volume pulse (DVP) to seek comparison in patients with PLMS and OSA.

METHODS

Forty-nine adult male subjects, without known comorbidities that could affect arterial stiffness or on vasoactive medication, were retrospectively identified and categorized into controls (n = 8), PLMS (n = 13), OSA (n = 17), and OSA/PLMS (n = 11). The cutoff for PLMS was a periodic limb movement index (PLMI) > 15 events/h, and for OSA an apnea-hypopnea index (AHI) > 10 events/h. SIDVP was derived from the raw data of photoplethysmography of the nocturnal polysomnography, averaged for 2 min prior to sleep study initiation (baseline), after completion in the morning, and every half hour after sleep onset.

RESULTS

The groups were age/body mass index-matched. Controls showed lower baseline, morning, and overall SIDVP compared to the other groups (p < 0.01). Patients with PLMS (PLMI: 50.69 ± 9.7 events/h) and the OSA group (AHI: 29.7 ± 2 events/h) demonstrated similar overall SIDVP (6.78 ± 0.08 versus 6.94 ± 0.04, respectively, p = 0.5), whereas the OSA/PLMS (AHI: 29.35 ± 8, PLMI: 50.63 ± 7.2) group demonstrated the highest (7.40 ± 0.06, p < 0.001).

CONCLUSIONS

Based on an easily reproducible and applicable marker of large arterial stiffness, patients with significant PLMS had higher SIDVP when compared to controls and comparable to those with moderate/severe OSA. The OSA/PLMS group had the highest SIDVP, implying a possible additive effect of OSA and PLMS on arterial stiffness.

The association between sleep-disordered breathing and aortic stiffness in a community cohort

OBJECTIVE

Sleep-disordered breathing is associated with hypertension and cardiovascular disease. Increased aortic stiffness is one possible linking mechanism. We evaluated the association between sleep-disordered breathing and aortic stiffness in a community-based sample.

METHODS

Our community-based cross-sectional observational study included 381 participants from the Framingham Heart Study (55% women, mean age 58.0 S.D. = 9.4 years, 51% ethnic minorities). Polysomnographically derived apnea-hypopnea index and CT90% (cumulative % sleep time with oxyhemoglobin saturation <90%) quantified sleep-disordered breathing severity. Carotid-femoral pulse wave velocity, the gold-standard measure of aortic stiffness, was calculated using arterial applanation tonometry-derived waveforms and body surface measured transit distance. We assessed associations between sleep-disordered breathing and carotid-femoral pulse wave velocity using multivariable regression. We adjusted for age, sex, race, body mass index, diabetes, alcohol consumption, hormone replacement therapy, cholesterol/high-density lipoprotein, lipid-lowering therapy, anti-hypertensive medication, smoking, hypertension, and prevalent cardiovascular disease.

RESULTS

After multivariable adjustment, carotid-femoral pulse wave velocity was associated with both apnea-hypopnea index (β = 0.03, 95% CI: 0.002-0.07, p= 0.04) and CT90% (β = 0.05, 95% CI: 0.005-0.1, p= 0.03). The adjusted mean carotid-femoral pulse wave velocity was 9.43 (95% CI: 9.12-9.74), 9.76 (95% CI: 9.25-10.26), and 10.15 (95% CI: 9.37-10.92) m/s, respectively, in subjects with apnea-hypopnea index <5, 5-14.9, and ≥15 events/h.

CONCLUSIONS

In a community-based sample of middle aged and older men and women, sleep-disordered breathing was associated with increased carotid-femoral pulse wave velocity, a strong predictor of cardiovascular risk.

Diet and exercise improve chemoreflex sensitivity in patients with metabolic syndrome and obstructive sleep apnea

OBJECTIVE

Chemoreflex hypersensitity was caused by obstructive sleep apnea (OSA) in patients with metabolic syndrome (MetS). This study tested the hypothesis that hypocaloric diet and exercise training (D+ET) would improve peripheral and central chemoreflex sensitivity in patients with MetS and OSA.

METHODS

Patients were assigned to: (1) D+ET (n = 16) and (2) no intervention control (C, n = 8). Minute ventilation (VE, pre-calibrated pneumotachograph) and muscle sympathetic nerve activity (MSNA, microneurography) were evaluated during peripheral chemoreflex sensitivity by inhalation of 10% O2 and 90% N2 with CO2 titrated and central chemoreflex by 7% CO2 and 93% O2 for 3 min at study entry and after 4 months.

RESULTS

Peak VO2 was increased by D+ET; body weight, waist circumference, glucose levels, systolic/diastolic blood pressure, and apnea-hypopnea index (AHI) (34 ± 5.1 vs. 18 ± 3.2 events/h, P = 0.04) were reduced by D+ET. MSNA was reduced by D+ET at rest and in response to hypoxia (8.6 ± 1.2 vs. 5.4 ± 0.6 bursts/min, P = 0.02), and VE in response to hypercapnia (14.8 ± 3.9 vs. 9.1 ± 1.2 l/min, P = 0.02). No changes were found in the C group. A positive correlation was found between AHI and MSNA absolute changes (R = 0.51, P = 0.01) and body weight and AHI absolute changes (R = 0.69, P < 0.001).

CONCLUSIONS

Sympathetic peripheral and ventilatory central chemoreflex sensitivity was improved by D+ET in MetS+OSA patients, which may be associated with improvement in sleep pattern.

Translational approaches to understanding metabolic dysfunction and cardiovascular consequences of obstructive sleep apnea

Obstructive sleep apnea (OSA) is known to be independently associated with several cardiovascular diseases including hypertension, myocardial infarction, and stroke. To determine how OSA can increase cardiovascular risk, animal models have been developed to explore the underlying mechanisms and the cellular and end-organ targets of the predominant pathophysiological disturbance in OSA-intermittent hypoxia. Despite several limitations in translating data from animal models to the clinical arena, significant progress has been made in our understanding of how OSA confers increased cardiovascular risk. It is clear now that the hypoxic stress associated with OSA can elicit a broad spectrum of pathological systemic events including sympathetic activation, systemic inflammation, impaired glucose and lipid metabolism, and endothelial dysfunction, among others. This review provides an update of the basic, clinical, and translational advances in our understanding of the metabolic dysfunction and cardiovascular consequences of OSA and highlights the most recent findings and perspectives in the field.

Obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is a common clinical condition in which the throat narrows or collapses repeatedly during sleep, causing obstructive sleep apnoea events. The syndrome is particularly prevalent in middle-aged and older adults. The mechanism by which the upper airway collapses is not fully understood but is multifactorial and includes obesity, craniofacial changes, alteration in upper airway muscle function, pharyngeal neuropathy and fluid shift towards the neck. The direct consequences of the collapse are intermittent hypoxia and hypercapnia, recurrent arousals and increase in respiratory efforts, leading to secondary sympathetic activation, oxidative stress and systemic inflammation. Excessive daytime sleepiness is a burden for the majority of patients. OSAS is also associated with cardiovascular co-morbidities, including hypertension, arrhythmias, stroke, coronary heart disease, atherosclerosis and overall increased cardiovascular mortality, as well as metabolic dysfunction. Whether treating sleep apnoea can fully reverse its chronic consequences remains to be established in adequately designed studies. Continuous positive airway pressure (CPAP) is the primary treatment modality in patients with severe OSAS, whereas oral appliances are also widely used in mild to moderate forms. Finally, combining different treatment modalities such as CPAP and weight control is beneficial, but need to be evaluated in randomized controlled trials. For an illustrated summary of this Primer, visit: http://go.nature.com/Lwc6te.

Minimal nocturnal oxygen saturation predicts future subclinical carotid atherosclerosis: the Wisconsin sleep cohort

Previous data on the associations between nocturnal oxygen saturation parameters and carotid atherosclerosis are conflicting. We examined the prospective associations of nocturnal oxygen saturation (SaO2 ) and cardiovascular disease (CVD) risk factors with carotid intima-media thickness (IMT) and plaques. We used data on 689 Wisconsin sleep cohort participants who had baseline overnight polysomnography followed by carotid ultrasonography a mean (SD) of 7.8 (2.5) years later. Far wall common carotid IMT was measured using B-mode ultrasound. Bilateral common, bifurcation and internal carotid artery segments were evaluated for plaque score. Participants (8) were aged 56 years (55% male); 32% had hypertension and mean body mass index (BMI) was 31 (7) kg m(2). Mean and minimum nocturnal SaO2 were 95% (2) and 86% (7), respectively. Mean percentage sleep time with SaO2 < 90% was 2% (8). Both mean (odds ratio [OR]: 0.60 lower plaque count per 5% higher mean SaO2, 95% confidence interval [CI]: 0.38-0.96, P = 0.033) and minimum SaO2 (OR: 0.88 lower plaque count per 5% higher minimum SaO2, 95% CI: 0.80-0.97, P = 0.013) predicted carotid plaque score after adjusting for age, sex and BMI. Minimum SaO2 predicted future plaque score after adding adjustment for traditional CVD risk factors (OR: 0.90 lower plaque count per 5% higher minimum SaO2, 95% CI: 0.81-0.99, P = 0.038). Mean SaO2 was not associated with carotid IMT after CVD risk factor adjustment. We conclude that minimum nocturnal SaO2 is an independent predictor of future carotid plaque burden. Other nocturnal SaO2 parameters are not associated with future carotid IMT or plaques after adjusting for traditional CVD risk factors.

Sleep Apnea and Stroke

Stroke is the second leading cause of death worldwide and often has devastating consequences for affected individuals in terms of chronic disability. Traditional risk factors such as age, male sex, ethnicity, hypertension, and atrial fibrillation explain 60%-80% of the risk of stroke. Obstructive sleep apnea (OSA) is highly prevalent in individuals who have had a stroke and its emerging role as a potential modifiable risk factor for stroke has been recognized in the most recent American Heart Association stroke guidelines, which recommend consideration of screening for and treatment of OSA in this regard. In this article we provide an overview of the current evidence-based knowledge related to stroke and sleep apnea. The main focus of this article is key pathophysiological mechanisms by which OSA might increase the risk for stroke. The effect of OSA on stroke outcomes and the efficacy of treatment of OSA on these outcomes is also discussed.

Sleep apnea is independently associated with peripheral arterial disease in the Hispanic Community Health Study/Study of Latinos

OBJECTIVE

Sleep apnea (SA) has been linked with various forms of cardiovascular disease, but little is known about its association with peripheral artery disease (PAD) measured using the ankle-brachial index. This relationship was evaluated in the Hispanic Community Health Study/Study of Latinos.

APPROACH AND RESULTS

We studied 8367 Hispanic Community Health Study/Study of Latinos participants who were 45 to 74 years of age. Sleep symptoms were examined with the self-reported Sleep Health Questionnaire. SA was assessed using an in-home sleep study. Systolic blood pressure was measured in all extremities to compute the ankle-brachial index. PAD was defined as ankle-brachial index <0.90 in either leg. Multivariable logistic regression was used to investigate the association between moderate-to-severe SA, defined as apnea-hypopnea index ≥15, and the presence of PAD. Analyses were adjusted for covariates. The prevalence of PAD was 4.7% (n=390). The mean apnea-hypopnea index was significantly higher among adults with PAD compared with those without (11.1 versus 8.6 events/h; P=0.046). After adjusting for covariates, moderate-to-severe SA was associated with a 70% increase in the odds of PAD (odds ratio, 1.7; 95% confidence interval, 1.1-2.5; P=0.0152). This association was not modified by sex (P=0.8739). However, there was evidence that the association between moderate-to-severe SA and PAD varied by Hispanic/Latino background (P<0.01). Specifically, the odds were stronger in Mexican (adjusted odds ratio, 2.9; 95% confidence interval, 1.3-6.2) and in Puerto Rican Americans (adjusted odds ratio, 2.0; 95% confidence interval, 0.97-4.2) than in other backgrounds.

CONCLUSIONS

Moderate-to-severe SA is associated with higher odds of PAD in Hispanic/Latino adults.

Sleepiness, inflammation and oxidative stress markers in middle-aged males with obstructive sleep apnea without metabolic syndrome: a cross-sectional study

BACKGROUND

The simultaneous occurrence of metabolic syndrome and excessive daytime sleepiness are very common in obstructive sleep apnea (OSA) patients. Both conditions, if present in OSA, have been reported to be associated with inflammation and disruption of oxidative stress balance that impair the cardiovascular system. To verify the impact of daytime sleepiness on inflammatory and oxidative stress markers, we evaluated OSA patients without significant metabolic disturbance.

METHODS

Thirty-five male subjects without diagnostic criteria for metabolic syndrome (Adult Treatment Panel III) were distributed into a control group (n = 10) (43 ± 10.56 years, apnea-hypopnea index - AHI 2.71 ± 1.48/hour), a non-sleepy OSA group (n = 11) (42.36 ± 9.48 years, AHI 29.48 ± 22.83/hour) and a sleepy OSA group (n = 14) (45.43 ± 10.06 years, AHI 38.20 ± 25.54/hour). Excessive daytime sleepiness was considered when Epworth sleepiness scale score was ≥ 10. Levels of high-sensitivity C-reactive protein, homocysteine and cysteine, and paraoxonase-1 activity and arylesterase activity of paraoxonase-1 were evaluated.

RESULTS

Patients with OSA and excessive daytime sleepiness presented increased high-sensitivity C-reactive protein levels even after controlling for confounders. No significant differences were found among the groups in paraoxonase-1 activity nor arylesterase activity of paraoxonase-1. AHI was independently associated and excessive daytime sleepiness tended to have an association with high-sensitivity C-reactive protein.

CONCLUSIONS

In the absence of metabolic syndrome, increased inflammatory response was associated with AHI and daytime sleepiness, while OSA was not associated with abnormalities in oxidative stress markers.

OSA and depression are common and independently associated with refractory angina in patients with coronary artery disease

OBJECTIVE

Refractory angina is a severe form of coronary artery disease (CAD) characterized by persistent angina despite optimal medical therapy. OSA and depression are common in patients with stable CAD and may contribute to a poor prognosis. We hypothesized that OSA and depression are more common and more severe in patients with refractory angina than in patients with stable CAD.

METHODS

We used standardized questionnaires and full polysomnography to compare consecutive patients with well-established refractory angina vs consecutive patients with stable CAD evaluated for coronary artery bypass graft surgery.

RESULTS

Patients with refractory angina (n = 70) compared with patients with stable CAD (n = 70) were similar in sex distribution (male, 61.5% vs 75.5%; P = .07) and BMI (29.5 ± 4 kg/m2 vs 28.5 ± 4 kg/m2, P = .06), and were older (61 ± 10 y vs 57 ± 7 y, P = .013), respectively. Patients with refractory angina had significantly more symptoms of daytime sleepiness (Epworth Sleepiness Scale score, 12 ± 6 vs 8 ± 5; P < .001), had higher depression symptom scores (Beck Depression Inventory score, 19 ± 8 vs 10 ± 8; P < .001) despite greater use of antidepressants, had a higher apnea-hypopnea index (AHI) (AHI, 37 ± 30 events/h vs 23 ± 20 events/h; P = .001), higher proportion of oxygen saturation < 90% during sleep (8% ± 13 vs 4% ± 9, P = .04), and a higher proportion of severe OSA (AHI ≥ 30 events/h, 48% vs 27%; P = .009) than patients with stable CAD. OSA (P = .017), depression (P < .001), higher Epworth Sleepiness Scale score (P = .007), and lower sleep efficiency (P = .016) were independently associated with refractory angina in multivariate analysis.

CONCLUSIONS

OSA and depression are independently associated with refractory angina and may contribute to poor cardiovascular outcome.

Effect of obstructive sleep apnea hypopnea syndrome on lipid profile: a meta-regression analysis

BACKGROUND

Obstructive sleep apnea (OSA) is associated with obesity, metabolic syndrome, and dyslipidemia, which may be related to decrease androgen levels found in OSA patients. Dyslipidemia may contribute to atherosclerosis leading to increasing risk of heart disease.

METHODS

Systematic review was conducted using PubMed and Cochrane library by utilizing different combinations of key words; sleep apnea, obstructive sleep apnea, serum lipids, dyslipidemia, cholesterol, total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), and triglyceride (TG). Inclusion criteria were: English articles, and studies with adult population in 2 groups of patients (patients with OSA and without OSA). A total 96 studies were reviewed for inclusion, with 25 studies pooled for analysis.

RESULTS

Sixty-four studies were pooled for analysis; since some studies have more than one dataset, there were 107 datasets with 18,116 patients pooled for meta-analysis. All studies measured serum lipids. Total cholesterol pooled standardized difference in means was 0.267 (p = 0.001). LDL cholesterol pooled standardized difference in means was 0.296 (p = 0.001). HDL cholesterol pooled standardized difference in means was -0.433 (p = 0.001). Triglyceride pooled standardized difference in means was 0.603 (p = 0.001). Meta-regression for age, BMI, and AHI showed that age has significant effect for TC, LDL, and HDL. BMI had significant effect for LDL and HDL, while AHI had significant effect for LDL and TG.

CONCLUSION

Patients with OSA appear to have increased dyslipidemia (high total cholesterol, LDL, TG, and low HDL).

Critical evaluation of screening questionnaires for obstructive sleep apnea in patients undergoing coronary artery bypass grafting and abdominal surgery

BACKGROUND

Obstructive sleep apnea (OSA) is an independent risk factor for complications after surgery. However, OSA remains largely under recognized, and questionnaires designed to detect OSA have shown inconsistent results. Patients with cardiovascular diseases may not present with the typical symptoms of OSA. We therefore sought to compare the performance of screening questionnaires of patients referred for coronary artery bypass grafting (CABG) versus abdominal surgery (Abd surgery).

METHODS

We studied 40 consecutive patients referred for CABG [29 men; age 56 ± 7 years; body mass index (BMI) 30 ± 4 kg/m(2)], and 41 referred to Abd Surgery matched for age, gender, and BMI (28 men; age 56 ± 8 years; BMI 29 ± 5 kg/m(2)). All patients were evaluated with validated questionnaires to predict OSA (STOP-Bang and Berlin), Epworth sleepiness scale (ESS) and full overnight polysomnography.

RESULTS

The prevalence of OSA (apnea-hypopnea index ≥15 events/hour) in the CABG and Abd surgery groups was similar (52 and 41 %, respectively, p = 0.32). The Berlin questionnaire showed similar sensitivity (67 vs. 82 %, p = 0.17) but lower specificity in the CABG group (26 vs. 62 %, p = 0.02). The STOP-BANG questionnaire had a high sensitivity (90 vs. 94 %, p = 0.42) but low specificity (5 vs. 13 %, p = 0.25) in the CABG and Abd surgery groups, respectively. Patients referred for CABG slept less (323 [285-376] vs. 378 [308-415] minutes, p = 0.04) but had lower levels of daytime sleepiness than Abd surgery patients had (ESS, 6 ± 4 vs. 9 ± 5; p = 0.01, respectively).

CONCLUSIONS

Presenting clinical characteristics of OSA are modulated by the population evaluated and may affect the performance of screening questionnaires.