Obstructive Sleep Apnea and Cardiovascular Morbidities: A Review Article

Hypoglossal Nerve Stimulation and Cardiovascular Outcomes for Patients With Obstructive Sleep Apnea: A Randomized Clinical Trial

Importance

Sham-controlled trials are needed to characterize the effect of hypoglossal nerve stimulation (HGNS) therapy on cardiovascular end points in patients with moderate-severe obstructive sleep apnea (OSA).

Objective

To determine the effect of therapeutic levels of HGNS, compared to sham levels, on blood pressure, sympathetic activity, and vascular function.

Design, Setting, and Participants

This double-blind, sham-controlled, randomized crossover therapy trial was conducted from 2018 to 2022 at 3 separate academic medical centers. Adult patients with OSA who already had an HGNS device implanted and were adherent and clinically optimized to HGNS therapy were included. Participants who had fallen asleep while driving within 1 year prior to HGNS implantation were excluded from the trial. Data analysis was performed from January to September 2022.

Interventions

Participants underwent a 4-week period of active HGNS therapy and a 4-week period of sham HGNS therapy in a randomized order. Each 4-week period concluded with collection of 24-hour ambulatory blood pressure monitoring (ABPM), pre-ejection period (PEP), and flow-mediated dilation (FMD) values.

Main Outcomes and Measures

The change in mean 24-hour systolic blood pressure was the primary outcome, with other ABPM end points exploratory, and PEP and FMD were cosecondary end points.

Results

Participants (n = 60) were older (mean [SD] age, 67.3 [9.9] years), overweight (mean [SD] body mass index, calculated as weight in kilograms divided by height in meters squared, 28.7 [4.6]), predominantly male (38 [63%]), and had severe OSA at baseline (mean [SD] apnea-hypopnea index, 33.1 [14.9] events/h). There were no differences observed between active and sham therapy in 24-hour systolic blood pressure (mean change on active therapy, -0.18 [95% CI, -2.21 to 1.84] mm Hg), PEP (mean change on active therapy, 0.11 [95% CI, -5.43 to 5.66] milliseconds), or FMD (mean change on active therapy, -0.17% [95% CI, -1.88% to 1.54%]). Larger differences between active and sham therapy were observed in a per-protocol analysis set (n = 20) defined as experiencing at least a 50% reduction in apnea-hypopnea index between sham and active treatment.

Conclusions and Relevance

In this sham-controlled HGNS randomized clinical trial, mean 24-hour systolic blood pressure and other cardiovascular measures were not significantly different between sham and active HGNS therapy. Several methodologic lessons can be gleaned to inform future HGNS randomized clinical trials.

Trial Registration

ClinicalTrials.gov Identifier: NCT03359096.

Effectiveness of Continuous Positive Airway Pressure in Treating Hypertension in Obstructive Sleep Apnea: A Traditional Review

Almost one billion individuals worldwide suffer from obstructive sleep apnea (OSA). The most widely used treatment for OSA has been continuous positive airway pressure (CPAP), but its effect on blood pressure (BP) has been challenged. Our review aims to evaluate the effects of treating OSA with CPAP on BP and BP-related morbidities in adult hypertensive patients. Medical subject headings (MeSH) terminology was used to search the PubMed Central, MEDLINE, and PubMed databases for articles on the use of CPAP in OSA patients with hypertension. We selected various forms of academic writing, encompassing complete texts that were published in the English language. The study included a total of 21 papers. OSA is a serious health concern associated with a higher risk of cardiovascular disease, kidney disease, pulmonary hypertension, and aortic stiffness, which is brought on by the periodic hypoxia caused by nocturnal respiratory episodes. For individuals with moderate-to-severe OSA, CPAP therapy has been shown to have a considerable long-term benefit with a median drop of 11 mm Hg, and high adherence results in a decrease in diastolic BP. CPAP therapy directly lowers BP in OSA patients with a body mass index (BMI) of more than 30 kg/m2 and has also demonstrated improvement in early signs of atherosclerosis with lower nocturnal systolic BP levels. OSA patients with resistant hypertension also experienced lower BP after using CPAP for a year. Therefore, our findings suggest that obesity, hypersomnolence, high nocturnal BP, prolonged CPAP usage, and resistant hypertension may all have a major impact on the BP response to CPAP therapy in individuals with severe OSA.

The Predictive Role of the Triglyceride/Glucose Index in Patients with Hypercholesterolemia and Acute Ischemic Stroke

Background

The triglyceride/glucose index (TyG) reflects insulin resistance and predicts the risk of acute ischemic stroke (aIS). However, it is uncertain if this index predicts the severity and outcome of aIS because studies that addressed this question are few and all were performed in Asian subjects. Moreover, there are no studies that focused on patients with hypercholesterolemia.

Methods

We studied 997 Caucasian patients who were hospitalized for aIS and had hypercholesterolemia. aIS severity was assessed at admission with the National Institutes of Health Stroke Scale (NIHSS) and severe aIS was defined as NIHSS ≥ 21. The outcome was assessed with the functional outcome at discharge and with in-hospital mortality. An unfavorable functional outcome was defined as modified Rank in scale (mRs) at discharge between 3 and 6.

Results

The TyG index did not correlate with the NIHSS at admission (r = 0.032, p = NS) and was similar in patients with severe and non-severe aIS (8.7 ± 0.6 and 8.6 ± 0.6, respectively; p = NS). Risk factors for severe aIS were age, female gender, atrial fibrillation (AF) and diastolic blood pressure (DBP) at admission. The TyG index also did not correlate with the mRs(r = 0.037, p = NS) and was similar in patients who had unfavorable and favorable functional outcome (8.7 ± 0.6 and 8.6 ± 0.5, respectively; p = NS). Risk factors for unfavorable functional outcome were age, previous ischemic stroke, body mass index and the NIHSS at admission. The TyG index was similar in patients who died during hospitalization and patients who were discharged (8.7 ± 0.6 and 8.7 ± 0.6, respectively; p = NS). Risk factors for in-hospital mortality were AF and DBP and NIHSS at admission.

Conclusions

The TyG index does not appear to be associated with the severity or the outcome of aIS. Nevertheless, since there are few relevant data in Caucasians and the TyG index is an inexpensive and widely available biomarker, more studies in this ethnic group are required to determine the predictive role of this index in patients with aIS.

mRNA, lncRNA, and circRNA expression profiles in a new aortic dissection murine model induced by hypoxia and Ang II

Background and aims

Aortic dissection (AD) is a cardiovascular emergency with degeneration of the aortic media. Mounting evidence indicates obstructive sleep apnea (OSA) as an independent risk factor for AD development with unknown mechanisms. This study aims to establish a stable murine model of OSA-related AD (OSA-AD) and uncover the potential changes in gene transcripts in OSA-AD.

Materials and methods

ApoE^–/– mice were exposed to the chronic intermittent hypoxia (CIH) system combined with Ang II administration to establish the OSA-AD model. Pathological staining was performed to exhibit the physiological structure of the mouse aorta. The SBC mouse ceRNA microarray was used to identify significantly differentially expressed (DE) mRNAs, DE long-non-coding RNAs (DElncRNAs), and DE circular RNAs (DEcircRNAs) in OSA-AD tissues. Subsequently, bioinformatics analysis, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genome (KEGG), and protein–protein interaction (PPI) analyses, were performed to evaluate the function of the significantly differentially expressed transcripts (DETs). The hub genes were confirmed using quantitative real-time polymerase chain reaction (qRT-PCR).

Results

ApoE^–/– mice exposed to CIH and Ang II showed a high ratio of aortic accident (73.33%) and significant aortic diameter dilatation (1.96 ± 0.175 mm). A total of 1,742 mRNAs, 2,625 lncRNAs, and 537 circRNAs were identified as DETs (LogFC ≥ 1.5 or ≤ –1.5, P < 0.05). GO and KEGG analyses demonstrated that the differentially expressed mRNAs (DEmRNAs) were most enriched in cell proliferation, migration, apoptosis, inflammation, and hypoxia-related terms, which are closely related to aortic structural homeostasis. The PPI network contained 609 nodes and 934 connections, the hub genes were highlighted with the CytoHubba plugin and confirmed by qRT-PCR in AD tissues. KEGG pathway analysis revealed that the cis-regulated genes of DElncRNAs and circRNAs-host genes were enriched in aortic structural homeostasis-related pathways.

Conclusion

Our findings help establish a de novo OSA-AD animal model using ApoE^–/– mice. Many DEmRNAs, DElncRNAs, and DEcircRNAs were screened for the first time in OSA-AD tissues. Our findings provide useful bioinformatics data for understanding the molecular mechanism of OSA-AD and developing potential therapeutic strategies for OSA-AD.

Frequency-specific alterations in intrinsic low-frequency oscillations in newly diagnosed male patients with obstructive sleep apnea

Purpose

Previous studies found abnormal low-frequency spontaneous brain activity related to cognitive impairment in patients with obstructive sleep apnea (OSA). However, it is unclear if low-frequency spontaneous brain activity is related to specific frequency bands in OSA patients. In this study, we used the amplitude of low-frequency fluctuation (ALFF) method in patients with OSA to explore characteristics of spontaneous brain activity in the classical (0.01–0.1 Hz) and five sub-frequency bands (slow-2 to slow-6) and analyzed the relationship between spontaneous brain activity and clinical evaluation was analyzed.

Patients and methods

Resting-state magnetic resonance imaging data and clinical assessments were collected from 52 newly-diagnosed OSA patients and 62 healthy controls (HCs). We calculated the individual group ALFF values in the classical and five different sub-frequency bands. A two-sample t-test compared ALFF differences, and one-way analysis of variance explored interactions in frequency bands between the two groups.

Results

ALFF values in the OSA group were lower than those in the HC group in the bilateral precuneus/posterior cingulate cortex, bilateral angular gyrus, left inferior parietal lobule, brainstem, and right fusiform gyrus. In contrast, ALFF values in the OSA group were higher than those in the HC group in the bilateral cerebellum posterior lobe, bilateral superior frontal gyrus, bilateral middle frontal gyrus, left inferior frontal gyrus, left inferior temporal gyrus, and left fusiform gyrus. Some ALFF values in altered brain regions were associated with body mass index, apnea-hypopnea index, neck circumference, snoring history, minimum SaO₂, average SaO₂, arousal index, oxygen reduction index, deep sleep period naming, abstraction, and delayed recall in specific frequency bands.

Conclusion

Our results indicated the existence of frequency-specific differences in spontaneous brain activity in OSA patients, which were related to cognitive and other clinical symptoms. This study identified frequency-band characteristics related to brain damage, expanded the cognitive neuroimaging mechanism, and provided additional OSA neuroimaging markers.

The Case for Early Use of Glucagon-like Peptide-1 Receptor Agonists in Obstructive Sleep Apnea Patients with Comorbid Diabetes and Metabolic Syndrome

Patients with obstructive sleep apnea (OSA) have high rates of co-occurring type 2 diabetes, hypertension, obesity, stroke, congestive heart failure, and accelerated atherosclerotic cardiovascular diseases. These conditions frequently require multiple medications, raising the risk of polypharmacy, adverse drug-drug and drug-disease interactions, decreased quality of life, and increased healthcare cost in these patients. The current review of extant literature presents evidence supporting glucagon-like peptide-1 receptor agonists (GLP-1RA) as one pharmacologic intervention that provides a "one-stop shop" for OSA patients because of the multiple effects GLP-1RA has on comorbidities (e.g., hypertension, diabetes, obesity, metabolic syndrome, and atherosclerotic cardiovascular diseases) that commonly co-occur with OSA. Examples of glucagon-like peptide-1 receptor agonists approved by the FDA for diabetes (some of which are also approved for obesity) are liraglutide, exenatide, lixisenatide, dulaglutide, semaglutide, and albiglutide. Prescribing of GLP-1RAs to address these multiple co-occurring conditions has enormous potential to reduce polypharmacy, cost, and adverse drug events, and to improve quality of life for patients living with OSA and diabetes. We thus strongly advocate for increased and early use of GLP-1RA in OSA patients with co-occurring diabetes and other cardiometabolic conditions common in OSA.

Anxiety, depression and sleepiness in OSA patients treated with barbed reposition pharyngoplasty: a prospective study

PURPOSE

To evaluate the efficacy of barbed reposition pharyngoplasty (BRP) on sleepiness, anxiety, and depression o adult patients with obstructive sleep apnea (OSA).

METHODS

We performed a prospective multicentric study to assess functional outcomes in 20 OSA patients treated with BRP and compare the results with an observational group of 20 subjects. All recruited subjects performed at baseline and 6-months postoperative follow-up Polysomnography (PSG), daytime sleepiness scoring using the Epworth Sleepiness Scale (ESS), and anxiety and depression evaluation via the Beck Anxiety Inventory (BAI) and the Beck Depression Inventory-II (BDI-II) questionnaires.

RESULTS

At follow-up the BRP demonstrated greater improvements in AHI (8.92 ± 2.29 vs. 30.66 ± 2.56; p < 0.001) and ODI (7.65 ± 2.39 vs. 24.55 ± 3.20; p < 0.001) than control at intergroup analysis. Surgical group reported significant data in daytime sleepiness (5.15 ± 1.19 vs. 13.15 ± 1.35; p < 0.001), anxiety (12.65 ± 3.11 vs. 24.2 ± 2.37; p < 0.001), and depression domains (5.85 ± 1.19 vs. 17.55 ± 3.24; p < 0.001). AHI, ODI, and advanced age have been shown to multiple regression as independent predictors of treatment response for mood domains (p < 0.001; p = 0.02; p = 0.041, respectively).

CONCLUSIONS

Patients with OSA may benefit from palate surgery, reducing not only the apnea and hypopnea index, daytime sleepiness but also associated mood comorbidities. However, further studies are needed to confirm our preliminary results to validate the evidence to date reported.

Endothelial Dysfunction and Cardiovascular Risk in Obstructive Sleep Apnea: A Review Article

Obstructive sleep apnea (OSA) is a respiratory condition during sleep caused by repeated pauses in breathing due to upper airway obstruction. It is estimated that OSA affects 30% of the population, but only 10% are well diagnosed due to the absence of a well-defined symptomatology and poor screening tools for early diagnosis. OSA is associated to an endothelial dysfunction inducing several biological responses such as hypoxia, hypercapnia and oxidative stress, among others. OSA also triggers respiratory, nervous, metabolic, humoral and immunity system activations that increase the possibility of suffering a cardiovascular (CV) disease. In this review, we expose different studies that show the relationship between OSA and endothelial dysfunction and its association with CV pathologies like hypertension, and we define the most well-known treatments and their limitations. Additionally, we describe the potential future directions in OSA research, and we report clinical features such as endothelial progenitor cell alterations that could act as biomarkers for the development of new diagnostic tools and target therapies.

Association of Retinal Vascular Manifestation and Obstructive Sleep Apnea (OSA): A Narrative Review

Obstructive sleep apnea (OSA) is characterized by frequent episodes of partial or complete obstruction of the airway during sleep causing repeated episodes of apnea. OSA is more prevalent in middle-aged and older adults. OSA is associated with numerous ocular manifestations, including retinal manifestations. Literature highlighted the clear association between OSA and numerous ocular conditions including glaucoma and papilledema. This comprehensive and narrative review aims to summarize up-to-date clinical research concerning the association of OSA and vascular conditions that affect the retina. OSA is associated with the central serous chorioretinopathy (CSC), retinal vein occlusion (RVO), hypertensive retinopathy (HTRP) and development of diabetic retinopathy (DR). Sympathetic activation, hypoxia, and hormonal dysregulation all lead to serious retinal vascular conditions that will worsen OSA patients’ quality of life. It is important to refer patients with newly diagnosed OSA to an ophthalmology clinic for the appropriate test.

Obstructive sleep apnea and stroke severity: Impact of clinical risk factors

BACKGROUND

Specific clinical and demographic risk factors may be associated with improving or worsening neurologic outcomes within a population of acute ischemic stroke (AIS) patients with a history of obstructive sleep apnea (OSA). The objective of this study was to determine the changes in neurologic outcome during a 14-day recovery as it relates to initial stroke severity in AIS patients with OSA.

METHODS

This retrospective study analyzed baseline clinical risk factors and demographic data collected in a regional stroke center from January 2010 to June 2016. Our primary endpoint measure was the National Institutes of Health Stroke Scale (NIHSS) score and our secondary endpoint measures included the clinical factors associated with improving (NIHSS score ≤7) or worsening (NIHSS score >7) neurological outcome. The relative contribution of each variable to stroke severity and related outcome was determined using a logistic regression. The regression models were checked for the overall correct classification percentage using a Hosmer-Lemeshow test, and the sensitivity of our models was determined by the area under the receiver operating characteristic curve.

RESULTS

A total of 5469 AIS patients were identified. Of this, 96.89% did not present with OSA while 3.11% of AIS patients presented with OSA. Adjusted multivariate analysis demonstrated that in the AIS population with OSA, atrial fibrillation (AF) (odds ratio [OR] = 3.36, 95% confidence interval [CI], 1.289-8.762, P = 0.013) and changes in ambulatory status (OR = 2.813, 95% CI, 1.123-7.041, P = 0.027) showed an association with NIHSS score >7 while being Caucasian (OR = 0.214, 95% CI, 0.06-0.767, P = 0.018) was associated with NIHSS score ≤7.

CONCLUSION

In AIS patients with OSA, AF and changes in ambulatory status were associated with worsening neurological outcome while Caucasian patients were associated with improving neurological outcome. Our findings may have significant implications for patient stratification when determining treatment protocols with respect to neurologic outcomes in AIS patients with OSA.

Transcriptomic Changes of Murine Visceral Fat Exposed to Intermittent Hypoxia at Single Cell Resolution

Intermittent hypoxia (IH) is a hallmark of obstructive sleep apnea (OSA) and induces metabolic dysfunction manifesting as inflammation, increased lipolysis and insulin resistance in visceral white adipose tissues (vWAT). However, the cell types and their corresponding transcriptional pathways underlying these functional perturbations are unknown. Here, we applied single nucleus RNA sequencing (snRNA-seq) coupled with aggregate RNA-seq methods to evaluate the cellular heterogeneity in vWAT following IH exposures mimicking OSA. C57BL/6 male mice were exposed to IH and room air (RA) for 6 weeks, and nuclei from vWAT were isolated and processed for snRNA-seq followed by differential expressed gene (DEGs) analyses by cell type, along with gene ontology and canonical pathways enrichment tests of significance. IH induced significant transcriptional changes compared to RA across 14 different cell types identified in vWAT. We identified cell-specific signature markers, transcriptional networks, metabolic signaling pathways, and cellular subpopulation enrichment in vWAT. Globally, we also identify 298 common regulated genes across multiple cellular types that are associated with metabolic pathways. Deconvolution of cell types in vWAT using global RNA-seq revealed that distinct adipocytes appear to be differentially implicated in key aspects of metabolic dysfunction. Thus, the heterogeneity of vWAT and its response to IH at the cellular level provides important insights into the metabolic morbidity of OSA and may possibly translate into therapeutic targets.