Atrial Fibrillation and Sleep Apnoea: Guilt by Association?

Fibrinaloid Microclots and Atrial Fibrillation

Atrial fibrillation (AF) is a comorbidity of a variety of other chronic, inflammatory diseases for which fibrinaloid microclots are a known accompaniment (and in some cases, a cause, with a mechanistic basis). Clots are, of course, a well-known consequence of atrial fibrillation. We here ask the question whether the fibrinaloid microclots seen in plasma or serum may in fact also be a cause of (or contributor to) the development of AF. We consider known 'risk factors' for AF, and in particular, exogenous stimuli such as infection and air pollution by particulates, both of which are known to cause AF. The external accompaniments of both bacterial (lipopolysaccharide and lipoteichoic acids) and viral (SARS-CoV-2 spike protein) infections are known to stimulate fibrinaloid microclots when added in vitro, and fibrinaloid microclots, as with other amyloid proteins, can be cytotoxic, both by inducing hypoxia/reperfusion and by other means. Strokes and thromboembolisms are also common consequences of AF. Consequently, taking a systems approach, we review the considerable evidence in detail, which leads us to suggest that it is likely that microclots may well have an aetiological role in the development of AF. This has significant mechanistic and therapeutic implications.

Cx43 overexpression reduce the incidence of obstructive sleep apnea associated atrial fibrillation via the CaMKⅡγ/HIF-1 axis

BACKGROUND

Previous studies by our group have demonstrated chronic intermittent hypoxia (CIH) can decrease connexin 43 (Cx43) protein expression and thus increase atrial fibrillation (AF) inducibility. Cardiac sympathetic denervation (CSD) can reduce AF and increase Cx43 expression, however, the underlying molecular mechanisms and signaling pathways are still unclear.

METHODS AND RESULTS

An obstructive sleep apnea (OSA) rat model in vivo experiments and CIH H9c2 cells model in vitro experiments were used to figure out the roles and underlying mechanisms of Cx43 on OSA-associated AF. In this study, we examined the expression of Cx43, CaMKⅡγ, Bax, Caspase 3, HIF-1 Bcl-2, Tunel, and CPB/p300, to discover the association between proteins and the mechanism of regulatory changes. The downstream proteins of Cx43 were calculated by gene sequencing and data analysis. We found Cx43 expression was significantly downregulated after CIH exposure in rat and H9c2 cells. Active caspase-3 and Bax at CIH+8 h group are high, but decreased at OE+8 h group. The Bcl-2 expression was higher in the N and OE+8 h group than CIH+8 h group. TUNEL-positive cells from the CIH+8 h group was markedly higher. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated Cx43 overexpression inhibited the CaMKIIγ expression, and CaMKIIγ was involved in the HIF-1 signaling pathway. In addition, we also found Cx43 overexpression remarkably decreased the HIF-1 protein and p300 mRNA expression, which inhibits the CaMKIIγ/HIF-1 signaling pathway.

CONCLUSIONS

Taken together, these results suggested Cx43 overexpression inhibits the expression of calcium/calmodulin dependent protein CaMKⅡγ via the Cx43/CaMKIIγ/HIF-1 axis, which finally reduces the myocardial apoptosis and incidence of AF.

Cardiovascular and metabolic effects of a mandibular advancement device and continuous positive airway pressure in moderate obstructive sleep apnea: a randomized controlled trial

STUDY OBJECTIVES

It has been suggested that treatment for obstructive sleep apnea (OSA) reduces cardiovascular risk. So far, knowledge is limited about the difference in the reduction of this risk between mandibular advancement device (MAD) and continuous positive airway pressure (CPAP) therapy. The aim of this study was to compare the cardiovascular effects of MAD versus CPAP therapy in patients with moderate OSA.

METHODS

Patients with an apnea-hypopnea index (AHI) of 15-30 events/h were randomized to either MAD or CPAP therapy. At baseline and after 12-months follow-up, 24-hour ambulant blood pressure measurements (ABPM) and laboratory measurements were performed. ABPM consisted of 24-hour, daytime and night-time systolic (SBP) and diastolic blood pressure (DBP), and heart rate (HR) measurements. Laboratory measurements consisted of serum lipid values, creatinine, high-sensitivity c-reactive protein, plasma glucose, hemoglobin A1c (HbA1c), proinflammatory cytokines, soluble receptor for advanced glycation end products (sRAGE), chemokines and adhesion molecules.

RESULTS

Of the 85 randomized patients with moderate OSA, data were available for 54 patients (n=24 MAD, n=30 CPAP) at 12-month follow-up and showed that AHI significantly decreased with either therapy. In the MAD group, sRAGE and HbA1c were significantly higher after 12 months follow-up compared to baseline. No significant changes were found between MAD and CPAP treatment for all outcomes.

CONCLUSIONS

Treatment of patients with moderate OSA with either MAD or CPAP therapy had no profound effects on major cardiovascular risk factors after 12-months.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Title: MRA Therapy Versus CPAP Therapy in Moderate OSAS; Identifier: NCT01588275; URL: https://clinicaltrials.gov/ct2/show/NCT01588275.

The effectiveness of mandibular advancement devices in the treatment of obstructive sleep apnoea in adults: a methodological quality assessment of systematic reviews

BACKGROUND AND OBJECTIVES

There is growing interest in the use of mandibular advancement devices (MADs) for the treatment of obstructive sleep apnoea (OSA). Many systematic reviews (SRs) have investigated their effectiveness, but the applicability of SR results is affected by their methodological quality. This study critically appraises the methodological quality of SRs on this topic using a more detailed and updated version of A MeaSurement Tool to Assess systematic Reviews (AMSTAR).

MATERIALS AND METHODS

The literature was searched for SRs on MAD effectiveness in adults (≥18 years of age) for OSA treatment as compared with other non-surgical or surgical interventions or no intervention. Any objective or subjective measures of treatment outcome were considered eligible. AMSTAR2 was used to assess methodological quality.

RESULTS

The literature search yielded 64 potential reports; 10 met the eligibility criteria. All SRs had more than one critical flaw in AMSTAR2, so their methodological quality was rated as critically low. The most common issues included non-registration of study protocol, absence of list of excluded studies, no acknowledgment of fundings of included studies, no impact of risk of bias on SR results or interpretation and discussion of results, and data extraction not in duplicate.

LIMITATIONS

If a SR was not clearly identified by title or abstract as a SR or meta-analysis, it may have been missed during the screening process.

CONCLUSIONS

The methodological quality of SRs was suboptimal and warrants further improvement in order to provide strong evidence of MAD effectiveness and increase applicability of SR results for clinical decision-making.

Cardiac Sympathetic Denervation Suppresses Atrial Fibrillation and Blood Pressure in a Chronic Intermittent Hypoxia Rat Model of Obstructive Sleep Apnea

Background Chronic intermittent hypoxia ( CIH ) is a distinct pathological mechanism of obstructive sleep apnea ( OSA ), which is recognized as an independent risk factor for cardiovascular diseases. The aims of this study were to ascertain whether CIH induces atrial fibrillation ( AF ), to determine whether cardiac sympathetic denervation ( CSD ) can prevent it and suppress blood pressure, and to explore the potential molecular mechanisms involved. Methods and Results Sixty Sprague-Dawley male rats were randomly divided into 4 groups: sham, CSD , CIH , CIH + CSD . The rats were exposed either to CIH 8 hours daily or normoxia for 6 weeks. Cardiac pathology and structure were analyzed by hematoxylin and eosin staining and echocardiogram. ECG, blood pressure, body weight, and blood gas were recorded. Connexin 43 and tyrosine hydroxylase were detected by western blot, immunohistochemistry, and immunofluorescence. CIH induced atrial remodeling, and increased AF inducibility. CSD treatment reduced postapneic blood pressure rises and AF susceptibility, which could attenuate CIH -associated structural atrial arrhythmogenic remodeling. In addition, CIH -induced sympathetic nerve hyperinnervation and CSD treatment reduced sympathetic innervation, which may affect CIH -induced AF -associated sympathovagal imbalance. Connexin 43 was specifically downregulated in CIH , whereas CSD treatment increased its expression. Conclusions These results suggested CIH induces atrial remodeling, increases AF inducibility, results in sympathetic nerve hyperinnervation, and decreases connexin 43 expression, but CSD treatment reduces AF susceptibility, postapneic blood pressure increase, sympathetic innervation, and the alteration of Cx43, which may be a key point in the genesis of CIH -induced AF .

Long-Term Objective Adherence to Mandibular Advancement Device Therapy Versus Continuous Positive Airway Pressure in Patients With Moderate Obstructive Sleep Apnea

STUDY OBJECTIVES

Comparable health effects of mandibular advancement device (MAD) and continuous positive airway pressure (CPAP) therapy have been attributed to higher adherence with MAD compared with CPAP therapy. The objective of this study was to make a direct comparison of the objective adherence between MAD and CPAP in patients with moderate obstructive sleep apnea (OSA).

METHODS

Adherence was monitored for 12 months in 59 patients with moderate OSA (apnea-hypopnea index 15-30 events/h) as part of a randomized controlled trial. Objective adherence with MAD was assessed using the TheraMon microsensor. Objective adherence with CPAP was assessed using the built-in registration software with readout on SD card. Self-reported adherence with both therapies was assessed using a questionnaire.

RESULTS

Forty patients (68%) completed the study with the therapy to which they were randomly assigned. Median (interquartile range) objective adherence (h/night) in the 3rd month was 7.4 (5.2-8.2) for MAD and 6.8 (5.7-7.6) for CPAP (P = .41), compared to 6.9 (3.5-7.9) with MAD and 6.8 (5.2-7.6) with CPAP (P = .85) in the 12th month. There were no significant changes between the 3rd and 12th month for both MAD (P = .21) and CPAP (P = .46). Changes in adherence were not significantly different between MAD and CPAP (P = .51). Self-reported adherence was significantly higher with MAD than CPAP at all follow-ups. Self-reported adherence with CPAP was lower than objective CPAP adherence at the 6th and 12th month (P = .02).

CONCLUSIONS

Objective adherence with MAD and CPAP is comparable and consistent over time. Self-reported adherence is higher with MAD than with CPAP giving rise to interesting discrepancy between objective and self-reported adherence with CPAP.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Identifier: NCT01588275.

Clinical- and Cost-Effectiveness of a Mandibular Advancement Device Versus Continuous Positive Airway Pressure in Moderate Obstructive Sleep Apnea

STUDY OBJECTIVES

Limited evidence exists on the cost-effectiveness of mandibular advancement device (MAD) compared to continuous positive airway pressure (CPAP) therapy in moderate obstructive sleep apnea (OSA). Therefore, this study compares the clinical and cost-effectiveness of MAD therapy with CPAP therapy in moderate OSA.

METHODS

In a multicentre randomized controlled trial, patients with an apnea-hypopnea index (AHI) of 15 to 30 events/h were randomized to either MAD or CPAP. Incremental cost-effectiveness and cost-utility ratios (ICER/ICUR, in terms of AHI reduction and quality-adjusted life-years [QALYs, based on the EuroQol Five-Dimension Quality of Life questionnaire]) were calculated after 12 months, all from a societal perspective.

RESULTS

In the 85 randomized patients (n = 42 CPAP, n = 43 MAD), AHI reduction was significantly greater with CPAP (median reduction AHI 18.3 [14.8-22.6] events/h) than with MAD therapy (median reduction AHI 13.5 [8.5-18.4] events/h) after 12 months. Societal costs after 12 months were higher for MAD than for CPAP (mean difference €2.156). MAD was less cost-effective than CPAP after 12 months (ICER -€305 [-€3.003 to €1.572] per AHI point improvement). However, in terms of QALY, MAD performed better than CPAP after 12 months (€33.701 [-€191.106 to €562.271] per QALY gained).

CONCLUSIONS

CPAP was more clinically effective (in terms of AHI reduction) and cost-effective than MAD. However, costs per QALY was better with MAD as compared to CPAP. Therefore, CPAP is the first-choice treatment option in moderate OSA and MAD may be a good alternative.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Identifier: NCT01588275.

[Factors associated with atrial fibrillation in patients with hypertension and preserved left ventricle systolic function]

The objective of our study was to define factors associated with atrial fibrillation (AF) in patients with hypertension (HTN) and preserved left ventricle systolic function.

MATERIAL AND METHODS

Overall, 273 consecutive patients with HTN residing in urban area were included in the study. Patients were divided into 2 groups: the first - 60 patients with paroxysmal and persistent AF (33% men, age 62, 28 (10,02), the second - 213 patients without AF (33% men, age 59,37 (8,27).

RESULTS

Stepwise logistic regression analysis demonstrated AF presence was associated with alcohol intake ≥ 7 drinks per week (OR 4,12; 95%CI: 1,04-16,35), low physical activity (OR 3,18; 95% CI: 1,32-7,68), higher hip circumference (OR 1,19; 95% CI: 1,08-1,31) and history of HTN (OR 1,10; 95% CI: 1,04-1,17). BMI was not associated with presence of AF (OR 0,75; 95% CI: 0,61-0,91).

CONCLUSION

Thus in our urban population with hypertension, AF is associated with alcohol intake ≥ 7 drinks per week, low physical activity, increased hip circumference and history of hypertension.AF prevention should include modification of lifestyle.

Inflammation and atrial fibrillation: A comprehensive review

Atrial fibrillation (AF) has different underlying substrates. Atrial remodeling involves electrophysiological and structural abnormalities that promote the development and perpetuation of AF. Experimental and clinical data indicate that inflammation is implicated in the pathophysiology of atrial remodeling. The mechanistic links between atrial remodeling and inflammation are complex while diverse underlying diseases and conditions may affect these pathways. Inflammatory markers have also been associated with AF development, recurrence, perpetuation, total AF burden as well as with thromboembolic complications. The development of specific anti-inflammatory interventions in this setting seems to be challenging and complicated. Several agents with pleiotropic properties, including anti-inflammatory, have been tested in experimental and clinical settings with variable results. This updated review provides a concise overview of all available data regarding the role of inflammation in AF including the predictive role of inflammatory markers. Also, current knowledge and future directions on anti-inflammatory strategies are critically discussed.

Obstructive Sleep Apnea as a Risk Factor for Atrial Fibrillation: A Meta-Analysis

Objectives

To conducted a meta-analysis assessing the relationship between Obstructive Sleep Apnea (OSA) and the risk of Atrial Fibrillation (AF)

Methods

We searched PUBMED, Medline, and Cochrane Library using the keywords “atrial fibrillation”, “obstructive sleep apnea” and “sleep disordered breathing (SDB)”. All subjects included had established diagnosis of OSA/SDB. We then compared the occurrence of AF versus no AF. Analysis done with Comprehensive Meta-Analysis package V3 (Biostat, USA).

Results

A total of 579 results were generated. Duplicates were removed and 372 records were excluded based on irrelevant abstracts, titles, study design not consistent with the stated outcome, or full-text unavailable. Twelve studies meeting the inclusion criteria were reviewed in full-text; 2 of these articles were eventually removed due to unconfirmed OSA diagnostic modality, and one was also removed based on a control group inconsistent with the other studies. Therefore, a total of 9 studies were included (n=19,837). Sample sizes ranged from n=160 patients to n=6841 patients. The risk of AF was found to be higher among OSA/SDB versus control group (OR; 2.120, C.I: 1.845–2.436, Z; 10.598 p: <0.001). The heterogeneity observed for the pooled analysis was Q-value; 22.487 df (Q); 8 P-value; 0.004, I-squared; 64.424 Tau2; 0.098, suggesting appropriate study selection and moderate heterogeneity.

Conclusion

OSA/SDB is strongly associated with AFib confirming the notion that OSA/SDB populations are high risk for development of AF. Prospective studies are needed to ascertain the effect of the treatment of OSA/SDB for the prevention of AF, a growing health burden with serious consequences.

Cardiovascular effects of oral appliance therapy in obstructive sleep apnea: A systematic review and meta-analysis

Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity and mortality. This study systematically reviews the effects of oral appliance therapy (OAT) on a broad spectrum of cardiovascular outcomes. A literature search was performed up to December 31st 2016. Twenty-five relevant full-text articles were retrieved. Sixteen articles were considered methodologically sufficient, including 11 randomized controlled trials. Pooled data of the RCTs showed significant reductions in daytime systolic and diastolic blood pressure compared to baseline, but no significant reductions in heart rate, except for daytime heart rate when compared to inactive/placebo OAT. OAT and continuous positive airway pressure (CPAP) were equally effective in reducing blood pressure. Studies assessing the effect of OAT on heart rate variability, circulating cardiovascular biomarkers, and endothelial function and arterial stiffness, generally involved small numbers of patients, and were heterogeneous and inconclusive. Studies assessing the effect of OAT on cardiac function showed no effects on echocardiographic outcomes. One observational study showed that OAT was as effective as CPAP in reducing cardiovascular death. It could be speculated that OAT may lead to a reduction in long-term cardiovascular morbidity and mortality in OSA patients. However, further methodologically high quality, longitudinal studies are warranted to address this key question.