Causal Effect of Obstructive Sleep Apnea on Atrial Fibrillation: A Mendelian Randomization Study

Sleep breathing impairment index predicts incident atrial fibrillation in obstructive sleep apnea: A prospective cohort study

OBJECTIVES

Respiratory-event-associated hypoxia is crucial in cardiovascular comorbidities of obstructive sleep apnea (OSA). Intermittent hypoxia is an independent risk factor for atrial fibrillation (AF). The sleep breathing impairment index (SBII) is a novel metric that quantifies respiratory events and hypoxia, showing exceptional efficacy in predicting cardiovascular diseases. This study aims to evaluate the association between SBII and AF in OSA patients and compare the predictive performance of various OSA severity indices in predicting incident AF.

METHODS

This study included 1660 OSA patients without pre-existing AF from the Sleep Heart Health Study. Baseline SBII values were stratified into quartiles. Multivariate logistic regression analysis and restricted cubic spline analysis were conducted to explore the association between SBII and incident AF. Harrell's concordance statistic (C-statistic) was performed to compare the predictive value of SBII against other OSA severity indices.

RESULTS

During a mean follow-up of 5.3 years, 190 (11.5 %) OSA patients developed AF. SBII and hypoxic burden (HB) were associated with an increased risk of incident AF, with adjusted odds ratios of 1.87 (95 %CI: 1.14, 3.11; P = 0.015) and 2.01 (95 %CI: 1.20, 3.41; P = 0.009) for the third and fourth quartiles of SBII, respectively, and 1.70 (95 %CI: 1.04, 2.81; P = 0.038) for the fourth quartile of HB. Moreover, SBII had the largest C-statistic (0.75, 95 % CI: 0.709, 0.782) compared with HB, AHI, and ODI.

CONCLUSION

This study demonstrated that elevated SBII and HB levels increased the risk of incident AF in OSA patients, with SBII outperforming other OSA severity indices in predicting AF.

Interplay between gut microbiota and exosome dynamics in sleep apnea

Sleep-disordered breathing (SDB) is characterized by recurrent reductions or interruptions in airflow during sleep, termed hypopneas and apneas, respectively. SDB impairs sleep quality and is linked to substantive health issues including cardiovascular and metabolic disorders, as well as cognitive decline. Recent evidence suggests a link between gut microbiota (GM) composition and sleep apnea. Indeed, GM, a community of microorganisms residing in the gut, has emerged as a potential player in various diseases, and several studies have identified associations between sleep apnea and GM diversity along with shifts in bacterial populations. Additionally, the concept of "leaky gut," a compromised intestinal barrier with potentially increased inflammation, has emerged as another key player in the potential bidirectional relationship between GM and sleep apnea. One of the potential effectors could be extracellular vesicles (EVs) underlying gut-brain communication pathways that are relevant to sleep regulation and function. Thus, therapeutic implications afforded by targeting the GM or exosomes for sleep apnea management have surfaced as promising areas of research. This review explores current understanding of the relationship between GM, exosomes and sleep apnea, highlighting key research dynamics and potential mechanisms. A comprehensive review of the literature was conducted, focusing on studies investigating GM composition, intestinal barrier function and gut-brain communication in relation to sleep apnea.

Exploration of the relationships between immune cells, metabolic mediators, and atrial fibrillation: A bidirectional Mendelian randomization study

Studies have shown a close correlation among immune cells, plasma metabolites, and atrial fibrillation (AF). However, it is not clear if this association is related, which we used Mendelian randomization (MR) to investigate. We analyzed the association between immune cells, plasma metabolites, and AF by using summarized data from genome-wide association studies. Among them, we explored the associations between immune cells and AF by using bidirectional MR analysis. Combined with mediation analysis and multivariable MR, we further identified potential mediating plasmic metabolites. Results shows that causal relationships between 8 immune cell phenotypes and AF were identified with all 8 exhibiting reverse causality. Furthermore, 22 plasma metabolites have a causal relationship with AF. In addition, 2 immune cell phenotypes including CD25 on IgD + CD38dim and CX3CR1 on CD14 + CD16-monocyte, which were found to have causal relationships with 4 plasma metabolites, including 4-acetamidobutanoate levels, Octadecanedioylcarnitine (C18-DC) levels, Linolenate [alpha or gamma; (18:3n3 or 6)] levels, and N-acetyl-aspartyl-glutamate levels, which might be mediators. Ultimately, only 4-acetamidobutanoate levels, CD25 on IgD + CD38dim, and AF did appear to function as mediators (P-value = .030 < .05). In conclusion, immune cells and plasma metabolites are causally associated with AF. We have identified that 4-acetamidobutanoate levels appear to mediate the pathway linking CD25 on IgD + CD38dim to AF. This finding provides a new perspective for the early prevention and diagnosis of preatrial AF.

HIF1α/MIF/CD74 signaling mediated OSA-induced atrial fibrillation by promoting M1 macrophages polarization

BACKGROUND

Obstructive sleep apnea (OSA) is known to contribute to the occurrence and recurrence of atrial fibrillation (AF). However, the mechanism remains unknown.

METHODS

Chronic OSA rat model was established to elucidate the role of macrophages in OSA-induced AF. Moreover, to reveal the mechanisms underlying the abnormal polarization of macrophages induced by chronic OSA, co-culture cell model of macrophages and atrial myocytes was created.

RESULTS

Chronic OSA altered the pathological phenotype of atrial myocardial tissues, rendering it more susceptible to AF. Furthermore, chronic OSA promoted the polarization of M1 macrophages in the atrial tissue, and the AF susceptibility induced by chronic OSA was reversed upon clearance of macrophages. Then, we found that macrophages induced an atrial fibrillation-like phenotype in atrial myocytes, while atrial myocytes promoted M1 polarization of macrophages, under hypoxia/reoxygenation treatment. Moreover, hypoxia/reoxygenation upregulated the expression of hypoxia-inducible factor 1-α (HIF1α) in atrial myocytes, which subsequently promoted the expression of macrophage migration inhibitory factor (MIF) by binding to the promoter region. The increased expression of MIF further activated the expression of nuclear factor-kappa B (NF-κB) through interaction with CD74, ultimately leading to M1 macrophages polarization.

CONCLUSIONS

Increased polarization of M1-type macrophages was involved in the increased susceptibility to AF induced by OSA. In mechanism, OSA increased MIF expression by HIF1α in atrial myocytes. Then, MIF activated NF-κB expression by CD74 in macrophages, consequently driving the polarization of M1-type macrophages. Finally, M1 macrophages exacerbated atrial remodeling through the secretion of inflammatory cytokines, which contributed to the increased susceptibility to AF.

Causal Relationship Between Autism Spectrum Disorder and Inflammatory Bowel Disease: A Bidirectional Mendelian Randomization Study

Patients with autism spectrum disorder (ASD) are often accompanied by inflammatory bowel disease (IBD) in observational research; however, the potential causal link between the two conditions remains unknown. In this study, we used a two-sample bidirectional Mendelian randomization (MR) approach to assess the causal relationship between ASD and IBD and its main subtypes, Crohn's disease (CD), and ulcerative colitis (UC). Independent genetic instruments from a genome-wide association study (GWAS) for IBD (25,042 cases and 34,915 controls) were used to investigate the association of IBD with ASD data obtained from the PGC and the iPSYCH consortia (N = 46,351). The primary analysis employed the random effects inverse variance weighting (IVW) method. Horizontal pleiotropy was detected using the MR Egger regression and the MR-pleiotropy residual sum and outlier (MR-PRESSO) analysis while heterogeneity was detected using Cochran's Q. The IVW method indicated a positive causal relationship of IBD with ASD (odds ratio (OR) = 1.028, 95% confidence interval (CI) = 1.001-1.056, p = 0.042). In subtype analyses, CD was positively related to ASD (OR = 1.036; 95% CI = 1.004-1.069; p = 0.02); however, UC showed no relationship (OR = 1.021; 95% CI = 0.999-1.044; p = 0.065). In contrast, no evidence of a causal relationship between ASD and IBD or its subtypes (p > 0.05) was found. Our findings provided evidence in support of potential causal associations between IBD/CD and ASD.

Predicting Atrial Fibrillation Relapse Using Bayesian Networks: Explainable AI Approach

Background

Atrial fibrillation (AF) is a prevalent arrhythmia associated with significant morbidity and mortality. Despite advancements in ablation techniques, predicting recurrence of AF remains a challenge, necessitating reliable models to identify patients at risk of relapse. Traditional scoring systems often lack applicability in diverse clinical settings and may not incorporate the latest evidence-based factors influencing AF outcomes. This study aims to develop an explainable artificial intelligence model using Bayesian networks to predict AF relapse postablation, leveraging on easily obtainable clinical variables.

Objective

This study aims to investigate the effectiveness of Bayesian networks as a predictive tool for AF relapse following a percutaneous pulmonary vein isolation (PVI) procedure. The objectives include evaluating the model's performance using various clinical predictors, assessing its adaptability to incorporate new risk factors, and determining its potential to enhance clinical decision-making in the management of AF.

Methods

This study analyzed data from 480 patients with symptomatic drug-refractory AF who underwent percutaneous PVI. To predict AF relapse following the procedure, an explainable artificial intelligence model based on Bayesian networks was developed. The model used a variable number of clinical predictors, including age, sex, smoking status, preablation AF type, left atrial volume, epicardial fat, obstructive sleep apnea, and BMI. The predictive performance of the model was evaluated using the area under the receiver operating characteristic curve (AUC-ROC) metrics across different configurations of predictors (5, 6, and 7 variables). Validation was conducted through four distinct sampling techniques to ensure robustness and reliability of the predictions.

Results

The Bayesian network model demonstrated promising predictive performance for AF relapse. Using 5 predictors (age, sex, smoking, preablation AF type, and obstructive sleep apnea), the model achieved an AUC-ROC of 0.661 (95% CI 0.603-0.718). Incorporating additional predictors improved performance, with a 6-predictor model (adding BMI) achieving an AUC-ROC of 0.703 (95% CI 0.652-0.753) and a 7-predictor model (adding left atrial volume and epicardial fat) achieving an AUC-ROC of 0.752 (95% CI 0.701-0.800). These results indicate that the model can effectively estimate the risk of AF relapse using readily available clinical variables. Notably, the model maintained acceptable diagnostic accuracy even in scenarios where some predictive features were missing, highlighting its adaptability and potential use in real-world clinical settings.

Conclusions

The developed Bayesian network model provides a reliable and interpretable tool for predicting AF relapse in patients undergoing percutaneous PVI. By using easily accessible clinical variables, presenting acceptable diagnostic accuracy, and showing adaptability to incorporate new medical knowledge over time, the model demonstrates a flexibility and robustness that makes it suitable for real-world clinical scenarios.

Atrial fibrillation in young stroke patients: Associated factors and outcomes in a nationwide analysis

BACKGROUND AND PURPOSE

Knowledge about the prevalence of atrial fibrillation (AF) in young stroke patients, as well as its associated factors and outcomes, is scarce. Our objective was to analyse it.

METHODS

A retrospective analysis of the Spain Nationwide Minimum Basic Data Set (MBDS) (2016-2020), including ischaemic stroke (IS) patients aged 18 and 50 years, was conducted. Multivariate analyses were conducted to identify factors related to AF diagnosis.

RESULTS

Amongst 11,615 young IS patients, 426 (3.7%) had AF. Patients with AF were older (median age 45, interquartile range 42-48 vs. 44, interquartile range 40-47 years, p < 0.001) and displayed more incapacitating symptoms, higher in-hospital complications and were less often discharged home (p < 0.001). Multivariate analyses showed that older age (odds ratio [OR] 1.053, 95% confidence interval [CI] 1.032-1.074), obstructive sleep apnoea (OR 1.508, 95% CI 1.018-2.233), hyperthyroidism (OR 3.741, 95% CI 1.798-7.783), valvular heart disease (OR 6.094, 95% CI 4.261-8.716), congenital (OR 2.386, 95% CI 1.146-4.969) and non-congenital (OR 4.446, 95% CI 3.149-6.278) cardiopathies and heart failure (OR 3.098, 95% CI 1.905-5.037) were independently associated with higher probability of AF, whereas female gender (OR 0.647, 95% CI 0.516-0.812), diabetes mellitus (0.487, 95% CI 0.339-0.699), smoking (OR 0.617, 95% CI 0.501-0.759), patent foramen ovale (OR 0.210, 95% CI 0.111-0.396) and arterial dissection (OR 0.294, 95% CI 0.130-0.668) were associated with a lower probability.

CONCLUSIONS

In young IS patients, AF is associated with more in-hospital complications and disabling strokes. These findings emphasize the need to recognize AF in this demographic group, especially in patients with risk factors like hyperthyroidism and cardiomyopathies. Clinicians should assess these risk factors to ensure timely diagnosis and management of AF.

Unraveling the relationship between obstructive sleep apnea and osteoarthritis: A multivariate mendelian randomization highlighting the role of BMI as a confounding factor

BACKGROUND

Osteoarthritis (OA) and obstructive sleep apnea (OSA) are prevalent chronic conditions with emerging evidence suggesting a potential link. However, the causality of this association remains unclear, possibly influenced by confounders like high body mass index (BMI). This study aimed to explore causal relationships between OA and OSA using Mendelian randomization (MR).

METHODS

MR analysis was performed to assess causality between OA and OSA. Inverse variance weighting (IVW) was the primary MR method, complemented by sensitivity analyses, including MR steiger, MR-Egger, MR-PRESSO, weighted median, heterogeneity tests, and leave-one-out approaches to evaluate pleiotropy and confirm the robustness of the causal estimates. To exclude confounding effects of BMI, we also used a multivariate MR (MVMR).

RESULTS

After adjusting for BMI through MVMR, no significant causal relationship was identified between genetically predicted OSA and OA phenotypes, including knee (KOA) and hip osteoarthritis (HOA), suggesting that obesity largely drives the observed relationship between these conditions. Similarly, MR steiger doesn't support a causal effect from OA on OSA. Sensitivity analyses confirmed the robustness of these results, with no significant evidence of horizontal pleiotropy or heterogeneity affecting outcomes. The findings indicate that BMI acts as a critical confounder in the relationship between OSA and OA, rather than OSA directly contributing to OA development.

CONCLUSIONS

Our findings indicate that there is no significant causal relationship between genetically predicted OSA and OA after adjusting for BMI. These findings underscore obesity as the primary shared risk factor, highlighting the importance of weight management as a key strategy for mitigating the risks of both conditions. Future research should aim to validate these findings in diverse populations and explore other metabolic pathways that may contribute to these complex associations.

Impact of Obstructive Sleep Apnea on In-Stent Restenosis in Coronary Heart Disease Patients after Elective Drug-Eluting Stenting

Background

Extensive research has established obstructive sleep apnea (OSA) as a contributing factor to numerous cardiovascular and cerebrovascular diseases. However, whether OSA affects in-stent restenosis (ISR) after elective drug-eluting stenting is unclear. Therefore, the objective of this study was to examine the impact of OSA on ISR in patients with coronary heart disease (CHD) who underwent successful elective drug-eluting stent (DES) implantation.

Methods

This study retrospectively analyzed CHD patients who successfully underwent elective coronary stent implantation and overnight sleep breathing monitoring and were readmitted for coronary angiography due to symptoms of CHD at 12 to 26 months after percutaneous coronary intervention (PCI). OSA was diagnosed when the apnea-hypopnea index (AHI) was ≥5 events/hour. ISR was defined as >50% restenosis of the vessel diameter in which the DES was implanted. To explore the association between OSA and ISR among patients with CHD, multivariate logistic regression models were developed and utilized.

Results

This study enrolled 206 individuals who were diagnosed with CHD, with a mean age of 62.01 ± 10.27 years, and males constituted 76.2% of the patient population. After a median follow-up period of 15 months following DES implantation, there was a significant increase in the incidence of ISR among patients with moderate to severe OSA, increasing from 10.9% to 31.3% (p < 0.001). According to the fully adjusted model, the occurrence of ISR was found to be independently associated with the presence of OSA (OR: 3.247, 95% CI: 1.373-7.677, p = 0.007).

Conclusions

In individuals who underwent elective drug-eluting stenting, OSA is an independent risk factor for ISR.

Pathophysiology, molecular mechanisms, and genetics of atrial fibrillation

The development of atrial fibrillation (AF) is a highly complex, multifactorial process involving pathophysiologic mechanisms, molecular pathway mechanisms and numerous genetic abnormalities. The pathophysiologic mechanisms including altered ion channels, abnormalities of the autonomic nervous system, inflammation, and abnormalities in Ca2 + handling. Molecular pathway mechanisms including, but not limited to, renin-angiotensin-aldosterone (RAAS), transforming growth factor-β (TGF-β), oxidative stress (OS). Although in clinical practice, the distinction between types of AF such as paroxysmal and persistent determines the choice of treatment options. However, it is the pathophysiologic alterations present in AF that truly determine the success of AF treatment and prognosis, but even more so the molecular mechanisms and genetic alterations that lie behind them. One tiny clue reveals the general trend, and small beginnings show how things will develop. This article will organize the development of these mechanisms and their interactions in recent years.

Mediation effect of plasma metabolites on the relationship between immune cells and the risk of prostatitis: A study by bidirectional 2-sample and Bayesian-weighted Mendelian randomization

According to the findings of multiple observational studies, immune disorder was a risk factor for prostatitis. However, it remained unknown whether there was a direct causal relationship between immune cells and prostatitis or whether this relationship was mediated by plasma metabolites. Based on the pooled data of a genome-wide association study (GWAS), a genetic variant was used to predict the effects of 731 immunophenotypes on the risk of prostatitis and determine whether the effects were mediated by 1400 metabolites. The bidirectional 2-sample Mendelian randomization (MR) method was adopted to uncover the causal relationship between immunophenotypes and prostatitis. Subsequently, a 2-step MR method was employed to evaluate whether the metabolites mediated this causal relationship and quantify the mediating effects and the corresponding ratios. In addition, the Bayesian-weighted Mendelian randomization (BWMR) method was employed to verify the results. Among the 731 immunophenotypes analyzed, 16 had causal relationships with the risk of prostatitis, including 11 with positive correlations (P < .05, beta > 0) and 5 with negative correlations (P < .05, beta < 0). The MR analysis screened out 9 metabolites related to the risk of prostatitis. The X - 24344 levels mediated the causal relationship between CD3 on CD39+ activated Treg and prostatitis (mediation effect: 0.01; ratio: 9.82%). Both histidine betaine (hercynine) levels and the proline-to-glutamate ratio mediated the causal relationship between CD14-CD16+ monocyte absolute count and prostatitis, with the mediation effects of -0.016 (14.20%) and -0.008 (7.24%), respectively. The glutamine degradant levels mediated the causal relationship between HLA DR+ CD4+ %T cells and prostatitis, with a mediation effect of -0.012, accounting for 8.07% of the total. The present study indicated that the immune cell subsets predicted based on gene expression profiles were potentially beneficial or harmful risk factors of prostatitis, and plasma metabolites may serve as the mediating factors of the relationship. The study thus shed light on deciphering the immunologic mechanism of prostatitis.

Managing elderly patients with atrial fibrillation and multimorbidity: call for a systematic approach

INTRODUCTION

Atrial fibrillation (AF) is often accompanied by comorbidities. Not only cardiovascular but also non-cardiovascular comorbidities have been associated with AF. Multimorbidity is therefore a common finding in patients with AF, especially in elderly patients. Multimorbidity is associated with adverse outcomes, adds complexity to AF management, and poses a significant burden on healthcare costs. It is expected that the prevalence of elderly patients with multimorbidity will increase significantly. It is therefore crucial to outline implications for clinical practice and guide comprehensive multimorbidity management.

AREAS COVERED

This perspective article outlines multimorbidity in AF and the importance of comprehensive comorbidity management. It addresses current clinical practice guided by international guidelines and the need for integrated care including a patient-centered focus, comprehensive AF management, coordinated multidisciplinary care, and supporting technology. Moreover, it proposes a novel model of care delivery following a systematic approach to multimorbidity management.

EXPERT OPINION

Providing comprehensive care by means of a multidisciplinary team and patient engagement is crucial to provide optimal personalized care for elderly patients with AF and multimorbidity. A systematic integrated care approach seems promising, but further studies are needed to investigate the feasibility of a systematic approach and prioritization of comorbidity management in patients with multimorbidity.

Association of Obstructive Sleep Apnea on Heart Failure and Its Risk Factors: A Two-Step Mendelian Randomization Study

INTRODUCTION

Recent studies have indicated that obstructive sleep apnea (OSA) is linked to a higher likelihood of heart failure (HF). However, the causal connection between the two conditions is uncertain. We aimed to investigate the causal association of OSA with HF and its risk factors.

METHODS

The OSA summary statistics are derived from the FinnGen database, including 38,998 cases and 336,659 controls. HF summary statistics come from HERMES, the UK Biobank, and the FinnGen database. A two-sample mendelian randomization (MR) analysis was conducted to examine the causality of OSA on HF risk. Furthermore, the mediator effect of potential risk factors was assessed by a two-step MR.

RESULTS

The results of MR analysis demonstrated that genetically determined OSA is causal associated with the higher likelihood of HF (HERME: odds ratio [OR] = 1.222; 95% confidence interval [CI]: 1.091, 1.369; p = 5.19 × 10-4) (FinnGen: OR = 1.233; 95% CI: 1.129, 1.346; p = 3.32 × 10-6) (UK Biobank: OR = 1.002; 95% CI: 1.000, 1.003; p = 0.014). Two-step MR analysis indicated that obesity, blood glucose, depression, and other CVDs have significant mediating effects on the causal effect between OSA and HF.

CONCLUSION

This MR study emphasizes the causal effect of OSA on HF risk. Adiposity traits play a major role in the process of OSA leading to HF. Considering the detrimental impact of OSA on HF, it becomes imperative to prioritize the prevention and management of HF in individuals afflicted with OSA. The foremost intervention strategy should revolve around effective obesity management.

Genetically predicted small dense low-density lipoprotein cholesterol and ischemic stroke subtype: multivariable Mendelian randomization study

Purpose

Small dense low-density lipoprotein cholesterol (S-LDL-C) has been suggested as a particularly atherogenic factor for ischemic stroke (IS) in observational studies, but the causality regarding the etiological subtype remains unclear. This study aims to explore the causal effects of small dense low-density lipoprotein cholesterol (S-LDL-C), medium (M-LDL-C) and large (L-LDL-C) subfractions on the lifetime risk of ischemic stroke (IS) and main subtypes using two-sample Mendelian randomization (TSMR) design.

Methods

We identified genetic instruments for S-LDL-C, M-LDL-C and L-LDL-C from a genome-wide association study of 115 082 UK Biobank participants. Summary-level data for genetic association of any ischemic stroke (AIS), large artery stroke (LAS), small vessel stroke (SVS) and cardioembolic stroke (CES) were obtained from MEGASTROKE consortium. Accounting for the pleiotropic effects of triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C), we conducted multivariable TSMR analysis.

Results

In univariable TSMR, we found a causal association between genetically predicted S-LDL-C and LAS (IVW-FE: odds ratio (OR) = 1.481, 95% confidence interval (CI): 1.117-1.963, P = 0.006, q = 0.076) but not AIS, SVS or CES. No causal effects were observed for M-LDL-C or L-LDL-C in terms of AIS and IS subtype. In multivariable analysis, the causal association between S-LDL-C and LAS remained significant (IVE-MRE: OR = 1.329, 95% CI: 1.106-1.597, P = 0.002).

Conclusions

Findings supported a causal association between S-LDL-C and LAS. Further studies are warranted to elucidate the underlying mechanism and clinical benefit of targeting S-LDL-C.

Obstructive sleep apnea and 19 gastrointestinal diseases: a Mendelian randomization study

Background

Alterations gastrointestinal diseases (GDs) were reported in individuals with obstructive sleep apnea (OSA), however, the genetic background between OSA and GDs is still unclear.

Methods

This investigation employed Mendelian randomization (MR) analyses to evaluate the causal effect between OSA and 19 types of GDs (gastroesophageal reflux disease (GERD), ulcerative colitis, celiac disease, Crohn's disease, chronic gastritis, irritable bowel syndrome, primary biliary cholangitis, diverticular disease, gastroduodenal ulcer, acute pancreatitis, non-alcoholic fatty liver disease, primary sclerosing cholangitis, cirrhosis, calculus of bile duct, calculus of gallbladder, pancreatic cancer, gastric cancer, colorectal cancer, and esophageal cancer). The inverse-variance weighted (IVW) method was used to evaluate the main effects model of causality.

Results

This MR study suggests that OSA may play a causal role inflammation-related GDs (GERD, PIVW=5.94×10-9; gastroduodenal ulcer, PIVW=1×10-4; chronic gastritis, PIVW=0.0214; ulcerative colitis, PIVW=0.0296), and gallstones (calculi of the gallbladder, PIVW=0.0429; calculi of the bile duct, PIVW=0.0068). After accounting for obesity, type 2 diabetes, smoking, and alcohol consumption, the multivariate MR (MVMR) analysis identified that OSA is an independent risk factor for GERD, gastroduodenal ulcer, and calculus of the bile duct. The reverse MVMR analysis showed a causal effect of GERD on OSA. Besides, we did not find that the predisposition to OSA was associated with 4 cancers.

Conclusion

This MR analysis provides compelling evidence of an independent causal relationship between genetically predicted OSA and an elevated risk of inflammation-related GDs. Besides, no causal association was observed between OSA and cancers. Further studies should be carried out to verify our findings.

GWAS advancements to investigate disease associations and biological mechanisms

Genome-wide association studies (GWAS) have been instrumental in elucidating the genetic architecture of various traits and diseases. Despite the success of GWAS, inherent limitations such as identifying rare and ultra-rare variants, the potential for spurious associations, and in pinpointing causative agents can undermine diagnostic capabilities. This review provides an overview of GWAS and highlights recent advances in genetics that employ a range of methodologies, including Whole Genome Sequencing (WGS), Mendelian Randomization (MR), the Pangenome's high-quality T2T-CHM13 panel, and the Human BioMolecular Atlas Program (HuBMAP), as potential enablers of current and future GWAS research. State of the literature demonstrate the capabilities of these techniques in enhancing the statistical power of GWAS. WGS, with its comprehensive approach, captures the entire genome, surpassing the capabilities of the traditional GWAS technique focused on predefined Single Nucleotide Polymorphism (SNP) sites. The Pangenome's T2T-CHM13 panel, with its holistic approach, aids in the analysis of regions with high sequence identity, such as segmental duplications (SDs). Mendelian Randomization has advanced causative inference, improving clinical diagnostics and facilitating definitive conclusions. Furthermore, spatial biology techniques like HuBMAP, enable 3D molecular mapping of tissues at single-cell resolution, offering insights into pathology of complex traits. This study aims to elucidate and advocate for the increased application of these technologies, highlighting their potential to shape the future of GWAS research.

Atrial High-Rate Episodes in Elderly Patients: The Anticoagulation Therapy Dilemma

Atrial fibrillation (AF) has been associated with higher morbidity and mortality rates, especially in older patients. Subclinical atrial fibrillation (SCAF) is defined as the presence of atrial high-rate episodes (AHREs) > 190 bpm for 10 consecutive beats > 6 min and <24 h, as detected by cardiac implanted electronic devices (CIEDs). The selection of eligible patients for anticoagulation therapy among elderly individuals with AHREs detected through CIEDs remains a contentious issue. The meta-analysis of ARTESiA and NOAH-AFNET 6 clinical trials revealed that taking Edoxaban or Apixaban as oral anticoagulation therapy can reduce the risk of stroke by approximately 32% while increasing the risk of major bleeding by approximately 62%. However, it is still unclear which are, among patients with SCAF, those who can take the highest net clinical benefit from anticoagulant therapy. The present review summarizes the current evidence on this intriguing issue and suggests strategies to try to better stratify the risk of stroke and systemic embolism in patients with AHREs. We propose incorporating some parameters including chronic kidney disease (CKD), obesity, enlarged left atrial volume, the efficacy in blood pressure management, and frailty into the traditional CHA2DS2-VASc score. Future trials will be needed to verify the clinical usefulness of the proposed prognostic score mainly in the view of a personalized therapeutic approach in patients with SCAF.

Sleep apnea and ischemic stroke- a perspective for translational preclinical modelling

Obstructive sleep apnea (OSA) is associated with ischemic stroke. There is, however, a lack of knowledge on the exact cause-effect relationship, and preclinical models of OSA for experimental ischemic stroke investigations are not well characterized. In this review, we discuss sleep apnea and its relationship with stroke risk factors. We consider how OSA may lead to ischemic stroke and how OSA-induced metabolic syndrome and hypothalamic-pituitary axis (HPA) dysfunction could serve as therapeutic targets to prevent ischemic stroke. Further, we examine the translational potential of established preclinical models of OSA. We conclude that metabolic syndrome and HPA dysfunction, which are often overlooked in the context of experimental stroke and OSA studies, are crucial for experimental consideration to improve the body of knowledge as well as the translational potential of investigative efforts.

Association of sleep duration with atrial fibrillation/flutter mortality in the United States: a cross-sectional analysis

BACKGROUND

The association between sleep duration and atrial fibrillation risk is poorly understood, with inconsistent findings reported by several studies. We sought to assess the association between long sleep duration and mortality due to atrial fibrillation/atrial flutter (AF/AFL).

METHODS

The 2016-2020 Centers for Disease Control and Prevention (CDC) Wide-Ranging Online Data for Epidemiologic Research dataset was used to identify death records secondary to AF/AFL in the United States population. We used the 2018 Behavioral Risk Factor Surveillance System (BRFSS) dataset of sleep duration at the county level. All counties were grouped into quartiles based on the percentage of their population with long sleep duration (i.e., ≥ 7 h), Q1 being the lowest and Q4 the highest quartile. Age-adjusted mortality rates (AAMR) were calculated for each quartile. County Health Rankings for Texas were used to adjust the AAMR for comorbidities using linear regression.

RESULTS

Overall, the AAMR for AF/AFL were highest in Q4 (65.9 [95% CI, 65.5-66.2] per 100,000 person-years) and lowest in Q1 (52.3 [95% CI, 52.1-52.5] per 100,000 person-years). The AAMR for AF/AFL increased stepwise from the lowest to highest quartiles of the percentage population with long sleep duration. After adjustment for the county health ranks of Texas, long sleep duration remained associated with a significantly higher AAMR (coefficient 220.6 (95% CI, 21.53-419.72, p-value = 0.03).

CONCLUSIONS

Long sleep duration was associated with higher AF/AFL mortality. Increased focus on risk reduction for AF, public awareness about the importance of optimal sleep duration, and further research to elucidate a potential causal relationship between sleep duration and AF are warranted.

Identification of a Novel Target Implicated in Chronic Obstructive Sleep Apnea-Related Atrial Fibrillation by Integrative Analysis of Transcriptome and Proteome

Objective

This study aimed to identify a newly identified target involved in atrial fibrillation (AF) linked to chronic obstructive sleep apnea (COSA) through an integrative analysis of transcriptome and proteome.

Methods

Fifteen beagle canines were randomly assigned to three groups: control (CON), obstructive sleep apnea (OSA), and OSA with superior left ganglionated plexi ablation (OSA+GP). A COSA model was established by intermittently obstructing the endotracheal cannula during exhalation for 12 weeks. Left parasternal thoracotomy through the fourth intercostal space allowed for superior left ganglionated plexi (SLGP) ablation. In vivo open-chest electrophysiological programmed stimulation was performed to assess AF inducibility. Histological, transcriptomic, and proteomic analyses were conducted on atrial samples.

Results

After 12 weeks, the OSA group exhibited increased AF inducibility and longer AF durations compared to the CON group. Integrated transcriptomic and proteomic analyses identified 2422 differentially expressed genes (DEGs) and 1194 differentially expressed proteins (DEPs) between OSA and CON groups, as well as between OSA+GP and OSA groups (1850 DEGs and 1418 DEPs). The analysis revealed that differentially regulated DEGs were primarily enriched in mitochondrial biological processes in the CON-vs.-OSA and OSA-vs.-GP comparisons. Notably, the key regulatory molecule GSTZ1 was activated in OSA and inhibited by GP ablation.

Conclusion

These findings suggest that GSTZ1 may play a pivotal role in mitochondrial damage, triggering AF substrate formation, and increasing susceptibility to AF in the context of COSA.

Emerging trends and hot spots of sleep and genetic research: a bibliometric analysis of publications from 2002 to 2022 in the field

Background

Sleep is an important biological process and has been linked to many diseases; however, very little is known about which and how genes control and regulate sleep. Although technology has seen significant development, this issue has still not been adequately resolved. Therefore, we conducted a bibliometric analysis to assess the progress in research on sleep quality and associated genes over the past 2 decades. Through our statistical data and discussions, we aimed to provide researchers with better research directions and ideas, thus promoting the advancement of this field.

Methods

On December 29, 2022, we utilized bibliometric techniques, such as co-cited and cluster analysis and keyword co-occurrence, using tools such as CiteSpace, VOSviewer, and the Online Analysis Platform of Literature Metrology (http://bibliometric.com/), to conduct a thorough examination of the relevant publications extracted from the Web of Science Core Collection (WoSCC). Our analysis aimed to identify the emerging trends and hot spots in this field while also predicting their potential development in future.

Results

Cluster analysis of the co-cited literature revealed the most popular terms relating to sleep quality and associated genes in the manner of cluster labels; these included genome-wide association studies (GWAS), circadian rhythms, obstructive sleep apnea (OSA), DNA methylation, and depression. Keyword burst detection suggested that obstructive sleep apnea, circadian clock, circadian genes, and polygenic risk score were newly emergent research hot spots.

Conclusion

Based on this bibliometric analysis of the publications in the last 20 years, a comprehensive analysis of the literature clarified the contributions, changes in research hot spots, and evolution of research techniques regarding sleep quality and associated genes. This research can provide medical staff and researchers with revelations into future directions of the study on the pathological mechanisms of sleep-related diseases.

Associations of screen-based sedentary activities with all cause dementia, Alzheimer's disease, vascular dementia: a longitudinal study based on 462,524 participants from the UK Biobank

BACKGROUND

Current drug treatments for dementia aren't effective. Studying gene-environment interactions can help develop personalized early intervention strategies for Alzheimer's disease (AD). However, no studies have examined the relationship between screen-based sedentary activities and genetic susceptibility to AD risk, and further understanding of the causal relationship is also crucial.

METHODS

This study included 462,524 participants from the UK Biobank with a follow-up of 13.6 years. Participants' screen-based sedentary activities time was categorized into three groups based on recorded time: ≥ 4 h/day, 2-3 h/day, and ≤ 1 h/day. Cox proportional risk models were used to analyze the association between computer use/TV viewing groups and the risk of all-cause dementia, AD and vascular dementia (VD). Generalized linear model (GLM) were used to examine the relationship between screen-based sedentary activities and brain structure. Bidirectional Mendelian randomization (MR) was used to validate the causal relationship between TV viewing and AD.

RESULTS

Compared to TV viewing ≤ 1 h/day, 1)TV viewing 2-3 h/day was correlated with a higher risk of all-cause dementia (HR = 1.09, 95% CI:1.01-1.18, P < 0.05), and TV viewing ≥ 4 h/day was associated with a higher risk of all-cause dementia (HR = 1.29, 95% CI: 1.19-1.40, P < 0.001), AD (HR = 1.25, 95% CI:1.1-1.42, P < 0.001), and VD (HR = 1.24, 95% CI: 1.04-1.49, P < 0.05); 2) TV viewing ≥ 4 h/day was correlated with a higher AD risk at intermediate (HR = 1.34, 95% CI: 1.03-1.75, P < 0.001) and high AD genetic risk score (AD-GRS) (HR = 2.18, 95% CI: 1.65-2.87, P < 0.001);3) TV viewing 2-3 h/day [β = (-94.8), 95% CI: (-37.9) -(-151.7), P < 0.01] and TV viewing ≥ 4 h/day [β = (-92.94), 95% CI: (-17.42) -(-168.46), P < 0.05] were correlated with a less hippocampus volume. In addition, a causal effect of TV viewing times was observed on AD analyzed using MR Egger (OR = 5.618, 95%CI:1.502-21.013, P < 0.05).

CONCLUSIONS

There was a causal effect between TV viewing time and AD analyzed using bidirectional MR, and more TV viewing time exposure was correlated with a higher AD risk. Therefore, it is recommended that people with intermediate and high AD-GRS should control their TV viewing time to be less than 4 h/ day or even less than 1 h/day.

Causality Investigation between Gut Microbiota, Derived Metabolites, and Obstructive Sleep Apnea: A Bidirectional Mendelian Randomization Study

Various studies have highlighted the important associations between obstructive sleep apnea (OSA) and gut microbiota and related metabolites. Nevertheless, the establishment of causal relationships between these associations remains to be determined. Multiple mendelian randomization (MR) analyses were performed to genetically predict the causative impact of 196 gut microbiota and 83 metabolites on OSA. Two-sample MR was used to assess the potential association, and causality was evaluated using inverse variance weighted (IVW), MR-Egger, and weighted median (WM) methods. Multivariable MR (MVMR) was employed to ascertain the causal independence between gut microbiota and the metabolites linked to OSA. Additionally, Cochran's Q test, the MR Egger intercept test and the MR Steiger test were used for the sensitivity analyses. The analysis of the 196 gut microbiota revealed that genus_Ruminococcaceae (UCG009) (PIVW = 0.010) and genus_Subdoligranulum (PIVW = 0.041) were associated with an increased risk of OSA onset. Conversely, Family_Ruminococcaceae (PIVW = 0.030), genus_Coprococcus2 (PWM = 0.025), genus_Eggerthella (PIVW = 0.011), and genus_Eubacterium (xylanophilum_group) (PIVW = 0.001) were negatively related to the risk of OSA. Among the 83 metabolites evaluated, 3-dehydrocarnitine, epiandrosterone sulfate, and leucine were determined to be potential independent risk factors associated with OSA. Moreover, the reverse MR analysis demonstrated a suggestive association between OSA exposure and six microbiota taxa. This study offers compelling evidence regarding the potential beneficial or detrimental causative impact of the gut microbiota and its associated metabolites on OSA risk, thereby providing new insights into the mechanisms of gut microbiome-mediated OSA development.

Overall Obesity Not Abdominal Obesity Has a Causal Relationship with Obstructive Sleep Apnea in Individual Level Data

Objective

Both obstructive sleep apnea (OSA) and obesity are highly prevalent worldwide, and are intrinsically linked. Previous studies showed that obesity is one of the major risk factors for OSA, but the causality of the relationship is still unclear. The study was to investigate the causal relationships of overall obesity and abdominal obesity with OSA and its quantitative traits.

Methods

In this case-control study, a total of 7134 participants, including 4335 moderate-to-severe OSA diagnosed by standard polysomnography and 2799 community-based controls were enrolled. Anthropometric and biochemical data were collected. Mendelian randomization (MR) analyses were performed using the genetic risk score, based on 29 body mass index (BMI)- and 11 waist-hip-ratio (WHR)-associated single nucleotide polymorphisms as instrumental variables. The causal associations of these genetic scores with OSA and its quantitative phenotypes were analyzed.

Results

Obesity was strongly correlated with OSA in observational analysis (β= 0.055, P = 3.7 × 10-5). In MR analysis, each increase by one standard deviation in BMI was associated with increased OSA risk [odds ratio (OR): 2.21, 95% confidence interval (CI): 1.62-3.02, P = 5.57 × 10-7] and with 2.72-, 4.68-, and 3.25-fold increases in AHI, ODI, and MAI, respectively (all P < 0.05) in men. However, no causal associations were found between WHR and OSA risk or OSA quantitative traits in men and women.

Conclusion

Compared to abdominal obesity, overall obesity showed a causal relationship with OSA and its quantitative traits, especially in men.

How is Obstructive Sleep Apnea Associated with High Blood Pressure and Diabetes Mellitus Type 2? Clues from a Two-Step Mendelian Randomized Study

Background

Obstructive sleep apnea (OSA), high blood pressure (HBP), and type 2 diabetes mellitus (T2DM) have a close clinical relationship, but whether and how OSA affects HBP and T2DM is unclear.

Study Design and Methods

Two-step, two-sample Mendelian randomization techniques were applied using single-nucleotide polymorphisms as genetic instruments for exposure and mediators, thus minimizing bias due to confounding factors and reverse causality. The total effect of OSA on HBP and T2DM was categorized into direct and mediating effects based on the mediating factors.

Results

Two-sample MR analysis showed that OSA increased the risk of HBP (odds ratio [OR] = 1.010, 95% confidence interval [CI], 1.002-1.018; P = 0.0121) and T2DM (OR = 1.140, 95% CI, 1.059-1.228; P = 0.0005). In the process of OSA caused by HBP, sex hormone-binding globulin (SHBG) (female, 4.47% mediation; male, 2.76% mediation), total testosterone (TT) (male, 3.72% mediation), bioavailable testosterone (BioT) (female, 7.74% mediation), high-density lipoprotein cholesterol (HDL-C) (3.25% mediation), and apolipoprotein A1 (ApoA1) (1.31% mediation) were individual contributors. SHBG (female, 4.10% mediation; male, 1.58% mediation), TT (male, 3.69% mediation), BioT (female, 2.58% mediation), HDL-C (3.32% mediation), ApoA1 (2.14% mediation), and omega-6 fatty acids (2.33% mediation) may have mediating roles to varying degrees in the process of OSA caused by T2DM.

Interpretation

This MR study showed that OSA is a risk factor for HBP and T2DM, and the evaluation of mediators may help further reveal the specific mechanism by which OSA causes HBP and T2DM.

Causal association between psycho-psychological factors, such as stress, anxiety, depression, and irritable bowel syndrome: Mendelian randomization

BACKGROUND

Pathogenesis, diagnosis, and treatment of irritable bowel syndrome (IBS) have been reported to be challenging hotspots in clinical practice. Previous observational studies have found that stress, anxiety, depression, and other mental and psychological diseases are closely associated with IBS. This study aimed to further explore the causal relationships of these associations through Mendelian randomization (MR).

METHODS

The data needed for MR were obtained from publicly published genome-wide association databases. We performed a bidirectional, 2-sample MR analysis using instrumental variables (IV) associated with stress, anxiety, and depression, and other mental and psychological factors as exposures and IBS as the outcome. A reverse MR analysis with IBS as exposure and stress, anxiety, depression, and other mental and psychological factors as the outcomes was also performed. The inverse variance weighting (IVW) method was adopted as the main method of MR, and the causal effect between stress, anxiety, depression, and other mental and psychological factors and IBS was evaluated as the main result of the study. In addition, a series of sensitivity analyses was conducted to comprehensively evaluate the causal relationship between them.

RESULTS

Stress, anxiety, depression, and other mental and psychological factors were the underlying etiologies for IBS (odds ratio [OR] = 1.06, 95% confidence interval [CI]: 1.03-1.08), and they were positively correlated. Univariate analysis further supported the above conclusions (Depression, [OR = 1.31, 95% CI: 1.05-1.63, P = .016], Anxiety, [OR = 1.53, 95% CI: 1.16-2.03, P = .003]). However, in reverse MR analysis, we found that IBS did not affect stress, anxiety, depression, or other mental and psychological factors and that there was no causal relationship between IBS and stress, anxiety, depression, or other mental and psychological factors (P > .05).

CONCLUSION

This study demonstrates that mental and psychological factors are the underlying etiologies for IBS. These findings may provide important information for physicians regarding the clinical treatment of IBS.

Potential causal association between aspirin use and the reduced risk of hayfever or allergic rhinitis: a Mendelian randomization study

Background

The evidence from observational studies on the association between the use of aspirin and the risk of hayfever or allergic rhinitis is conflicting, with a dearth of high-quality randomized controlled trials.

Objective

This study aims to investigate the causal relationship between aspirin use and the risk of hayfever or allergic rhinitis.

Methods

We conducted a two-sample Mendelian randomization (MR) analysis using the inverse-variance weighted (IVW), weighted median, and MR-Egger regression methods. We utilized publicly available summary statistics datasets from genome-wide association studies (GWAS) meta-analyses on aspirin use in individuals of European descent (n = 337,159) as the exposure variable, and a GWAS on doctor-diagnosed hayfever or allergic rhinitis in individuals from the UK Biobank (n = 83,529) as the outcome variable.

Results

We identified 7 single nucleotide polymorphisms (SNPs) at genome-wide significance from the GWASs associated with aspirin use as instrumental variables (P<5×10-8; linkage disequilibrium r2 <0.1). The IVW method provided evidence supporting a causal association between aspirin use and reduced risk of hayfever or allergic rhinitis (β = -0.349, SE = 0.1356, P = 0.01008). MR-Egger regression indicated no causal association between aspirin use and hayfever or allergic rhinitis (β = -0.3742, SE = 0.3809, P = 0.371), but the weighted median approach yielded evidence of a causal association (β = -0.4155, SE = 0.1657, P = 0.01216). Cochran's Q test and the funnel plot indicated no evidence of heterogeneity and asymmetry, indicating no directional pleiotropy.

Conclusion

The findings of the MR analysis support a potential causal relationship between aspirin use and the reduced risk of hayfever or allergic rhinitis.

Five-year changes in alcohol intake and risk of atrial fibrillation: a Danish cohort study

AIMS

Alcohol intake is a well-established risk factor for atrial fibrillation (AF). However, evidence on the effects of changes in alcohol intake to primary AF prevention is sparse. The aim of this study was to examine the association between 5-year changes in alcohol intake and the risk of incident AF.

METHODS AND RESULTS

This study was based on the Danish cohort study Diet, Cancer and Health. Lifestyle factors were assessed using questionnaires at a recruitment research examination and a second examination 5 years later. Diagnoses of AF and comorbidities were retrieved from the Danish National Patient Registry. 43 758 participants without prior AF were included. The median age was 61 (25th-75th percentile 58-66) years and 54% were female. Over a median follow-up time of 15.7 years, 5312 participants had incident AF (incidence rate 8.6/1000 person-years). Compared with stable intake, increases in alcohol intake to ≥21 drinks/week from ≤6.9 drinks/week (HR: 1.38, 95% CI: 1.09-1.72) or 14-20.9 drinks/week (HR: 1.27, 95% CI: 1.01-1.59) at baseline were associated with a higher risk of AF. In contrast, we did not observe a statistically significant association between reductions in alcohol intake and the risk of AF.

CONCLUSION

A 5-year increase in alcohol intake was associated with a greater risk of AF compared with a stable low/moderate intake.

Evaluation of obstructive sleep apnea among consecutive patients with all patterns of atrial fibrillation using WatchPAT home sleep testing

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice and is associated with significant morbidity, mortality, and financial burden. Obstructive sleep apnea (OSA) is more common in individuals with AF and may impair the efficacy of rhythm control strategies including catheter ablation. However, the prevalence of undiagnosed OSA in all-comers with AF is unknown.

DESIGN

This pragmatic, phase IV prospective cohort study will test 250-300 consecutive ambulatory AF patients with all patterns of atrial fibrillation (paroxysmal, persistent, and long-term persistent) and no prior sleep testing for OSA using the WatchPAT system, a disposable home sleep test (HST). The primary outcome of the study is the prevalence of undiagnosed OSA in all-comers with atrial fibrillation.

RESULTS

Preliminary results from the initial pilot enrollment of approximately 15% (N = 38) of the planned sample size demonstrate a 79.0% prevalence of at least mild (AHI≥5) OSA or greater in consecutively enrolled patient with all patterns of AF.

CONCLUSIONS

We report the design, methodology, and preliminary results of our study to define the prevalence of OSA in AF patients. This study will help inform approaches to OSA screening in patients with AF for which there is currently little practical guidance.

CLINICAL TRIAL REGISTRATION

NCT05155813.

Causal effects of circulating vitamin levels on the risk of heart failure: a Mendelian randomization study

BACKGROUND

Observational studies suggest inverse associations between serum vitamin levels and the risk of heart failure (HF). However, the causal effects of vitamins on HF have not been fully elucidated. Here, we conducted a Mendelian randomization (MR) study to investigate the causal associations between genetically determined vitamin levels and HF.

METHODS

Genetic instrumental variables for circulating vitamin levels, including vitamins A, B, C, D, and E, which were assessed as either absolute or metabolite levels were obtained from public genome-wide association studies. Summary statistics for single-nucleotide-polymorphisms and HF associations were retrieved from the HERMES Consortium (47,309 cases and 930,014 controls) and FinnGen Study (30,098 cases and 229,612 controls). Two-sample MR analyses were implemented to assess the causality between vitamin levels and HF per outcome database, and the results were subsequently combined by meta-analysis.

RESULTS

Our MR study did not find significant associations between genetically determined circulating vitamin levels and HF risk. For absolute vitamin levels, the odds ratio for HF ranged from 0.97 (95% confidence interval [CI]: 0.85-1.09, P = 0.41) for vitamin C to 1.05 (95% CI: 0.61-1.82, P = 0.85) for vitamin A. For vitamin metabolites, the odds ratio ranged between 0.94 (95% CI: 0.75-1.19, P = 0.62) for α-tocopherol and 1.11 (95% CI: 0.98-1.26, P = 0.09) for γ-tocopherol.

CONCLUSION

Evidence from our study does not support the causal effects of circulating vitamin levels on HF. Therefore, there may be no direct beneficial effects of vitamin intake on the prevention of primary HF.

Causal associations of obstructive sleep apnea with cardiovascular disease: a Mendelian randomization study

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) had been associated with various cardiovascular diseases (CVDs) in observational studies, but causal inferences have not been confirmed. We used the Mendelian randomization (MR) study to explore the potential causal association between OSA with CVDs in the general population.

METHODS

We performed a two-sample MR analysis using five gene-wide significant single-nucleotide polymorphisms associated with OSA at genome-wide significance from the FinnGen study (N = 217 955) and 12 cardiovascular diseases from the UK Biobank and the genetic consortia. The inverse-variance weight was chosen as the primary analysis and was complemented by various sensitivity analyses. The study design applied univariable MR, multivariable MR, and mediation analysis.

RESULTS

MR analyses provide evidence of genetically predicted OSA on the risk of heart failure (odds ratio [OR],1.26; 95% confidence interval [CI],1.08 to 1.47), hypertension (OR,1.24; 95%CI, 1.11 to 1.39) and atrial fibrillation (OR,1.21; 95%CI,1.12 to 1.31). Multivariable MR indicated the adverse effect of OSA on heart failure persisted after adjusting BMI, smoking, drinking, and education (IVW OR,1.13; 95%CI, 1.01 to 1.27). However, the significance of hypertension and atrial fibrillation was dampened. Mediation analyses suggest that the causal association between OSA and heart failure is mediated in part by Apolipoprotein B, with a mediated portion of 9%.

CONCLUSIONS

This study suggested that genetically predicted OSA is a potential causal risk factor for heart failure based on a large-scale population. Nevertheless, further studies regarding ancestral diversity are needed to confirm the causal association between OSA and CVDs.

Genetic Predisposition to a Higher Whole Body Water Mass May Increase the Risk of Atrial Fibrillation: A Mendelian Randomization Study

BACKGROUND

Observational studies have found an association between increased whole body water mass (BWM) and atrial fibrillation (AF). However, the causality has yet to be confirmed. To provide feasible protective measures on disease development, we performed Mendelian randomization (MR) design to estimate the potential causal relationship between increased BWM and AF.

METHODS

We implemented a two-sample MR study to assess whether increased BWM causally influences AF incidence. For exposure, 61 well-powered genetic instruments extracted from UK Biobank (N = 331,315) were used as the proxies of BWM. Summary genetic data of AF were obtained from FinnGen (Ncase = 22,068; Ncontrol = 116,926). Inverse-variance weighted (IVW), MR-Egger and weighted median methods were selected to infer causality, complemented with a series of sensitivity analyses. MR-Pleiotropy Residual Sum and Outlier (MR-PRESSO) and Radial MR were employed to identify outliers. Furthermore, risk factor analyses were performed to investigate the potential mechanisms between increased BWM and AF.

RESULTS

Genetic predisposition to increased BWM was demonstrated to be significantly associated with AF in the IVW model (OR = 2.23; 95% CI = 1.47-3.09; p = 1.60 × 10^-7), and the result was consistent in other MR approaches. There was no heterogeneity or pleiotropy detected in sensitivity analysis. MR-PRESSO identified no outliers with potential pleiotropy after excluding outliers by Radial MR. Furthermore, our risk factor analyses supported a positive causal effect of genetic predicted increased BWM on edematous diseases.

CONCLUSIONS

MR estimates showed that a higher BWM could increase the risk of AF. Pathological edema is an important intermediate link mediating this causal relationship.

Machine learning for atrial fibrillation risk prediction in patients with sleep apnea and coronary artery disease

Background

Patients with sleep apnea (SA) and coronary artery disease (CAD) are at higher risk of atrial fibrillation (AF) than the general population. Our objectives were: to evaluate the role of CAD and SA in determining AF risk through cluster and survival analysis, and to develop a risk model for predicting AF.

Methods

Electronic medical record (EMR) database from 22,302 individuals including 10,202 individuals with AF, CAD, and SA, and 12,100 individuals without these diseases were analyzed using K-means clustering technique; k-nearest neighbor (kNN) algorithm and survival analysis. Age, sex, and diseases developed for each individual during 9 years were used for cluster and survival analysis.

Results

The risk models for AF, CAD, and SA were identified with high accuracy and sensitivity (0.98). Cluster analysis showed that CAD and high blood pressure (HBP) are the most prevalent diseases in the AF group, HBP is the most prevalent disease in CAD; and HBP and CAD are the most prevalent diseases in the SA group. Survival analysis demonstrated that individuals with HBP, CAD, and SA had a 1.5-fold increased risk of developing AF [hazard ratio (HR): 1.49, 95% CI: 1.18-1.87, p = 0.0041; HR: 1.46, 95% CI: 1.09-1.96, p = 0.01; HR: 1.54, 95% CI: 1.22-1.94, p = 0.0039, respectively] and individuals with chronic kidney disease (CKD) developed AF approximately 50% earlier than patients without these comorbidities in a period of 7 years (HR: 3.36, 95% CI: 1.46-7.73, p = 0.0023). Comorbidities that contributed to develop AF earlier in females compared to males in the group of 50-64 years were HBP (HR: 3.75 95% CI: 1.08-13, p = 0.04) CAD and SA in the group of 60-75 years were (HR: 2.4 95% CI: 1.18-4.86, p = 0.02; HR: 2.51, 95% CI: 1.14-5.52, p = 0.02, respectively).

Conclusion

Machine learning based algorithms demonstrated that CAD, SA, HBP, and CKD are significant risk factors for developing AF in a Latin-American population.

Bidirectional two-sample Mendelian randomization study of causality between rheumatoid arthritis and myocardial infarction

Background

Epidemiological evidence suggests an association between rheumatoid arthritis (RA) and myocardial infarction (MI). However, causality remains uncertain. Therefore, this study aimed to explore the causal association between RA and MI.

Methods

Using publicly available genome-wide association study summary datasets, bidirectional two-sample Mendelian randomization (TSMR) was performed using inverse-variance weighted (IVW), weighted median, MR-Egger regression, simple mode, and weighted mode methods.

Results

The MR results for the causal effect of RA on MI (IVW, odds ratio [OR] = 1.041, 95% confidence interval [CI]: 1.007-1.076, P = 0.017; weighted median, OR = 1.027, 95% CI: 1.006-1.049, P = 0.012) supported a causal association between genetic susceptibility to RA and an increased risk of MI. MR results for the causal effect of MI on RA (IVW, OR = 1.012, 95% CI: 0.807-1.268, P = 0.921; weighted median, OR = 1.069, 95% CI: 0.855-1.338, P = 0.556) indicated that there was no causal association between genetic susceptibility to MI and an increased risk of RA.

Conclusion

Bidirectional TSMR analysis supports a causal association between genetic susceptibility to RA and an increased risk of MI but does not support a causal association between genetic susceptibility to MI and an increased risk of RA.

Obesity as a risk factor for cardiac arrhythmias

Obesity is global health problem with an estimated three billion people worldwide being classified as overweight or obese. In addition to being associated with a range of adverse health outcomes, obesity is linked to higher risks of atrial and ventricular arrhythmias, as well as sudden cardiac death. Obesity is a multifactorial disease that often co-exists with hypertension, diabetes, and sleep apnoea, which are also independent risk factors for cardiac arrhythmias. Nevertheless, compelling evidence suggests that increasing adiposity is an independent proarrhythmic risk factor and that weight loss can be a mitigating and preventative intervention to reduce arrhythmia incidence. This review briefly outlines the economic and social burden of obesity and summarises evidence for the direct and indirect effects of increasing adiposity on risk of atrial and ventricular arrhythmias. The paper also summarises the evidence for electrocardiographic changes indicative of obesity-related atrial and ventricular remodelling and how weight reduction and management of comorbidity might reduce arrhythmic burden.

Leveraging genetic discoveries for sleep to determine causal relationships with common complex traits

Sleep occurs universally and is a biological necessity for human functioning. The consequences of diminished sleep quality impact physical and physiological systems such as neurological, cardiovascular, and metabolic processes. In fact, people impacted by common complex diseases experience a wide range of sleep disturbances. It is challenging to uncover the underlying molecular mechanisms responsible for decreased sleep quality in many disease systems owing to the lack of suitable sleep biomarkers. However, the discovery of a genetic component to sleep patterns has opened a new opportunity to examine and understand the involvement of sleep in many disease states. It is now possible to use major genomic resources and technologies to uncover genetic contributions to many common diseases. Large scale prospective studies such as the genome wide association studies (GWAS) have successfully revealed many robust genetic signals associated with sleep-related traits. With the discovery of these genetic variants, a major objective of the community has been to investigate whether sleep-related traits are associated with disease pathogenesis and other health complications. Mendelian Randomization (MR) represents an analytical method that leverages genetic loci as proxy indicators to establish causal effect between sleep traits and disease outcomes. Given such variants are randomly inherited at birth, confounding bias is eliminated with MR analysis, thus demonstrating evidence of causal relationships that can be used for drug development and to prioritize clinical trials. In this review, we outline the results of MR analyses performed to date on sleep traits in relation to a multitude of common complex diseases.

Continuous positive airway pressure reduces the incidence of atrial fibrillation in patients with obstructive sleep apnea: A Meta-Analysis and Systematic Review

INTRODUCTION

Obstructive sleep apnea (OSA) and atrial fibrillation (AF) are disorders that have increased in the United States during recent years. Earlier investigations have shown that underlying undiagnosed and unmanaged OSA plays a significant role in high rates and also as a trigger for newly diagnosed AF. Since the introduction of continuous positive airway pressure (CPAP) as a main therapy for OSA, more studies have evaluated the effect of CPAP on the development or recurrence of AF in OSA patients. However, sample sizes in a limited number of studies have been too small to conclude whether CPAP therapy has a significant effect on the development of AF in patients with OSA. The authors report results of their systematic review and meta-analysis summarizing what is currently known about the efficacy of CPAP for mitigating AF in patients with OSA.

METHOD

The authors systematically reviewed the published reports on CPAP use and the incidence of AF from PubMed, Google Scholar, EMBASE, Web of Science, meeting abstracts, and Cochrane databases published between January 2015 and November 2021. Study data were extracted by two reviewers and a random-effects meta-analysis was performed using RevMan version 5.4.

RESULTS

A total of 17 studies that met inclusion criteria were identified Studies included a total of 6,523 patients, 3,248 (49.8%) who used CPAP and 3,275 (50.2%) who did not use CPAP. In a random effects model, patients treated with CPAP showed a decrease in the incidence of AF (OR, 0.51; 95% CI; 0.27; 0.97, p = 0.04). High heterogeneity among the included studies was also observed (I2 = 97%).

CONCLUSION

Our results add to the increasing evidence that CPAP therapy may reduce the incidence of development of AF in patients with OSA. Prospective future studies and clinical trials are needed to refine our understanding of the relationship between OSA and AF and how CPAP may reduce cardiovascular disease development.

Obstructive sleep apnea and atrial fibrillation: insights from a bidirectional Mendelian randomization study

Background

Observational studies have suggested that obstructive sleep apnea (OSA) is in relation to atrial fibrillation (AF); however, these studies might be confounded and whether the relationship is causal remains unclear. We conducted a bidirectional Mendelian randomization (MR) study to clarify the causal inference between OSA and AF.

Methods

Genetic instruments for OSA and AF were obtained from genome-wide association studies. The fixed-effects inverse-variance weighted (IVW) method was used as the main method, supplemented by several sensitivity analyses. For replication, another AF dataset was used to validate the causal effect of OSA on AF. Furthermore, multivariable MR analyses were performed to obtain direct estimates adjusting for potential confounders.

Results

Genetic liability to OSA was found to be significantly associated with a higher AF risk in the fixed-effects IVW method [odds ratio (OR) 1.210; 95% CI 1.119–1.307; P = 1.51 × 10^–6]. The results were consistent in MR sensitivity analyses as well as in replication analyses, and the significance remained after adjusting for potential confounders. In the reverse MR analyses, there was no causal effect of AF on OSA.

Conclusions

Our study strengthened the causal evidence of genetically predicted OSA with a higher AF risk. Early screening and appropriate management of OSA might show anti-arrhythmic benefits.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01180-5.

Assessment of the Causal Effects of Obstructive Sleep Apnea on Atrial Fibrillation: A Mendelian Randomization Study

Background

Obstructive sleep apnea (OSA) and atrial fibrillation (AF) are epidemiologically correlated, but the causal relationship between them remains elusive. We aimed to explore the causal relationships between OSA and AF.

Method

Using both the Finnish biobank and publicly available genome-wide association study data (GWAS), we conducted a two-sample Mendelian randomization (MR) analysis to estimate the causal effect of OSA on AF, both in the primary analysis and replicated analysis. The inverse variance weighted MR was selected as the main method. To further test the independent causal effect of OSA on AF, we also performed multivariable MR (MVMR), adjusting for body mass index (BMI), hypertension, and coronary artery disease (CAD), respectively.

Results

In the primary analysis, OSA was significantly associated with the increased risk of AF (OR 1.21, 95% CI 1.11–1.32) and the replicated analysis showed consistent results (OR 1.17, 95% CI 1.05–1.30). Besides, there was no heterogeneity and horizontal pleiotropy observed both in the primary and replicated analysis. Further multivariable MR suggested that the causal relationships between OSA and AF exist independently of BMI and CAD. The MVMR result after the adjustment for hypertension is similar in magnitude and direction to the univariable MR. But it did not support a causal relationship between OSA and AF.

Conclusion

Our study found that genetically driven OSA causally promotes AF. This causal relationship sheds new light on taking effective measures to prevent and treat OSA to reduce the risk of AF.

Sleep Disordered Breathing, Obesity and Atrial Fibrillation: A Mendelian Randomisation Study

It remains unclear whether the association between obstructive sleep apnoea (OSA), a form of sleep-disordered breathing (SDB), and atrial fibrillation (AF) is causal or mediated by shared co-morbidities such as obesity. Existing observational studies are conflicting and limited by confounding and reverse causality. We performed Mendelian randomisation (MR) to investigate the causal relationships between SDB, body mass index (BMI) and AF. Single-nucleotide polymorphisms associated with SDB (n = 29) and BMI (n = 453) were selected as instrumental variables to investigate the effects of SDB and BMI on AF, using genetic association data on 55,114 AF cases and 482,295 controls. Primary analysis was conducted using inverse-variance weighted MR. Higher genetically predicted SDB and BMI were associated with increased risk of AF (OR per log OR increase in snoring liability 2.09 (95% CI 1.10-3.98), p = 0.03; OR per 1-SD increase in BMI 1.33 (95% CI 1.24-1.42), p < 0.001). The association between SDB and AF was not observed in sensitivity analyses, whilst associations between BMI and AF remained consistent. Similarly, in multivariable MR, SDB was not associated with AF after adjusting for BMI (OR 0.68 (95% CI 0.42-1.10), p = 0.12). Higher BMI remained associated with increased risk of AF after adjusting for OSA (OR 1.40 (95% CI 1.30-1.51), p < 0.001). Elevated BMI appears causal for AF, independent of SDB. Our data suggest that the association between SDB, in general, and AF is attributable to mediation or confounding from obesity, though we cannot exclude that more severe SDB phenotypes (i.e., OSA) are causal for AF.