Role of tumor necrosis factor alpha in the pathogenesis of atrial fibrillation: A novel potential therapeutic target?

CHA2DS2-VASc Score as Predictor of New-Onset Atrial Fibrillation and Mortality in Critical COVID-19 Patients

BACKGROUND

Pre-existing and new-onset atrial fibrillation (NOAF) is a common arrhythmia in COVID-19 patients and is related to increased mortality. CHA2DS2-VASc score was initially developed to evaluate thromboembolic risk in patients with AF. Moreover, it predicted adverse outcomes in other clinical conditions, including SARS-CoV-2 infection. We aimed to evaluate the association of CHA2DS2-VASc with NOAF, ICU length of stay (LOS) and mortality in critically ill COVID-19 patients. We also examined the relationship of NOAF with mortality. We reviewed the literature to describe the link between cardiovascular risk factors and inflammatory response of severe COVID-19.

METHODS AND RESULTS

We retrospectively studied 163 COVID-19 patients admitted to a level 3 general ICU from March 2020 to April 2022. Patients were of advanced age (median 64 years, IQR 56.5-71) and the majority of them were male (67.5%). Regarding NOAF, we excluded 12 patients with AF history. In this group, CHA2DS2VASc score was significantly elevated (3 IQR (1-4) versus 1 IQR (1-2.75), p = 0.003). Specifically, three components of CHA2DS2VASc were notably increased: age (p < 0.001), arterial hypertension (p = 0.042) and stroke (p = 0.047). ICU mortality was raised in the NOAF group [75.8% versus 34.8%, p < 0.001 OR 5.87, 95% CI (2.43, 14.17)]. This was significant even after adjusting for ICU clinical scores (APACHE II and SOFA). About mortality in the entire sample, survivors were younger (p = 0.001). Non-survivors had greater APACHE II (p = 0.04) and SOFA (p = 0.033) scores. CHA2DS2VASc score was positively associated with mortality [p = 0.031, OR 1.28, 95% CI (1.03, 1.6)]. ICU length of stay was associated with mortality (p = 0.016) but not with CHA2DS2VASc score (p = 0.842).

CONCLUSIONS

NOAF and CHA2DS2VASc score were associated with higher mortality in COVID-19 ICU patients. CHA2DS2VASc score was also associated with NOAF but not with ICU LOS.

Management of a Patient with Cardiovascular Disease Should Include Assessment of Primary and Secondary Immunodeficiencies: Part 2-Secondary Immunodeficiencies

BACKGROUND

Cardiovascular diseases are among the most common chronic diseases, generating high social and economic costs. Secondary immunodeficiencies occur more often than primary ones and may result from the co-occurrence of specific diseases, treatment, nutrient deficiencies and non-nutritive bio-active compounds that result from the industrial nutrient practices.

OBJECTIVES

The aim of this article is to present selected secondary immunodeficiencies and their impact on the cardiovascular system.

RESULTS

The treatment of a patient with cardiovascular disease should include an assess-ment for immunodeficiencies, because the immune and cardiovascular systems are closely linked.

CONCLUSIONS

Immune system dysfunctions can significantly affect the course of cardiovascular diseases and their treatment. For this reason, comprehensive care for a patient with cardiovascular disease requires taking into account potential immunodeficiencies, which can have a significant impact on the patient's health.

The interaction between neutrophils and atrial myocytes in the occurrence and development of atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is one of the most prevalent sustained cardiac arrhythmias, strongly associated with neutrophils. However, the underlying mechanism remain unclear. This study aims to explore the interaction between neutrophils and atrial myocytes in the pathogenesis of AF.

METHODS

Patch-clamp was employed to record the action potential duration (APD) and ion channels in HL-1 cells. Flow cytometry was used to assess the differentiation of neutrophils. The mRNA and protein levels of CACNA1C, CACNA2D, and CACNB2 in HL-1 cells were detected.

RESULTS

High-frequency electrical stimulation resulted in a shortening of the APD in HL-1 cells. Flow cytometry demonstrated that neutrophils were polarized into N1 phenotype when cultured with stimulated HL-1 cells medium. Compared to control neutrophils conditioned medium (CM), cocultured with TNF-α knockout neutrophils CM prolonged APD and the L-type Ca (2+) channel (LTCC) of HL-1 cells. Additionally, the expression of CACNA2D, CACNB2 and CACNA1C in HL-1 cells were upregulated. Compared with CACNA1C siRNA-transfected HL-1 cells treated with TNF-α siRNA-transfected neutrophils CM, the APD and LTCC of CACNA1C siRNA-transfected HL-1 cells were shortened in control N1 neutrophil CM. The APD and LTCC of control HL-1 cells were also shortened in control N1 neutrophil CM, but prolonged in TNF-α siRNA-transfected neutrophils CM.

CONCLUSION

These findings suggest that neutrophils were polarized into N1 phenotype in AF, TNF-α released from N1 neutrophils contributes to the pathogenesis of AF, via decreasing the APD and LTCC in atrial myocytes through down-regulation of CACNA1C expression.

Targeting the NLRP3 inflammasome signalling for the management of atrial fibrillation

Inflammatory signalling via the nod-like receptor (NLR) family pyrin domain-containing protein-3 (NLRP3) inflammasome has recently been implicated in the pathophysiology of atrial fibrillation (AF). However, the precise role of the NLRP3 inflammasome in various cardiac cell types is poorly understood. Targeting components or products of the inflammasome and preventing their proinflammatory consequences may constitute novel therapeutic treatment strategies for AF. In this review, we summarise the current understanding of the role of the inflammasome in AF pathogenesis. We first review the NLRP3 inflammasome pathway and inflammatory signalling in cardiomyocytes, (myo)fibroblasts and immune cells, such as neutrophils, macrophages and monocytes. Because numerous compounds targeting NLRP3 signalling are currently in preclinical development, or undergoing clinical evaluation for other indications than AF, we subsequently review known therapeutics, such as colchicine and canakinumab, targeting the NLRP3 inflammasome and evaluate their potential for treating AF.

GLP-1 receptor agonists and myocardial metabolism in atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Many medical conditions, including hypertension, diabetes, obesity, sleep apnea, and heart failure (HF), increase the risk for AF. Cardiomyocytes have unique metabolic characteristics to maintain adenosine triphosphate production. Significant changes occur in myocardial metabolism in AF. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been used to control blood glucose fluctuations and weight in the treatment of type 2 diabetes mellitus (T2DM) and obesity. GLP-1RAs have also been shown to reduce oxidative stress, inflammation, autonomic nervous system modulation, and mitochondrial function. This article reviews the changes in metabolic characteristics in cardiomyocytes in AF. Although the clinical trial outcomes are unsatisfactory, the findings demonstrate that GLP-1 RAs can improve myocardial metabolism in the presence of various risk factors, lowering the incidence of AF.

Antiarrhythmic effects of metformin

Atrial fibrillation/flutter (AF) is a major public health problem and is associated with stroke, heart failure, dementia, and death. It is estimated that 20%-30% of Americans will develop AF at some point in their life. Current medications to prevent AF have limited efficacy and significant adverse effects. Newer and safer therapies to prevent AF are needed. Ventricular arrhythmias are less prevalent than AF but may have significant consequences including sudden cardiac death. Metformin is the most prescribed, first-line medication for treatment of diabetes mellitus (DM). It decreases hepatic glucose production but also reduces inflammation and oxidative stress. Experimental studies have shown that metformin improves metabolic, electrical, and histologic risk factors associated with AF and ventricular arrhythmias. Furthermore, in large clinical observational studies, metformin has been associated with a reduced risk of AF in people with DM. These data suggest that metformin may have antiarrhythmic properties and may be a candidate to be repurposed as a medication to prevent cardiac arrhythmias. In this article, we review the clinical observational and experimental evidence for the association between metformin and cardiac arrhythmias. We also discuss the potential antiarrhythmic mechanisms underlying this association. Repurposing a well-tolerated, safe, and inexpensive medication to prevent cardiac arrhythmias has significant positive public health implications.

Association between inflammation markers and all-cause mortality in critical ill patients with atrial fibrillation: Analysis of the Multi-Parameter Intelligent Monitoring in Intensive Care (MIMIC-IV) database

Background

Inflammation is related to cardiovascular disease. Among the many inflammatory markers, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammatory index (SII) were considered as novel predictors for atherosclerosis outcomes. We aimed to investigate the impact of these inflammatory markers on the prognosis of patients with atrial fibrillation (AF).

Methods

We obtained data on AF patients from the Medical Information Mart for Intensive Care (MIMIC)-IV database. These patients were classified into two groups based on their survival status within 30 days. Then, they were divided into three groups based on the tertile of baseline NLR, PLR, and SII, respectively. We comprehensively explored the relationship between those inflammatory indicators and all-cause mortality in patients with AF by Kaplan-Meier analysis, multivariate Cox regression analysis, receiver operating characteristic (ROC) analyses, restricted cubic spline regression (RCS), and subgroup analysis.

Results

A total of 4562 patients with AF were included. Statistically significant differences were found between survivor and non-survivor groups for NLR, PLR and SII. Patients in the high tertile of the NLR had a higher mortality rate than those in the low and intermediate tertiles, as did patients in the PLR and the SII. NLR, PLR and SII were independently associated with increased risk of all-cause mortality. RCS showed that the 30-day and 365-day risk of death were linearly associated with increases in NLR, PLR, and SII, respectively.

Conclusion

NLR, PLR, and SII have the potential to be used as indicators for stratifying the risk of mortality in critically ill patients with AF.

Value of the NF-κB signalling pathway and the DNA repair gene PARP1 in predicting distant metastasis after breast cancer surgery

The DNA repair gene PARP1 and NF-κB signalling pathway affect the metastasis of breast cancer by influencing the drug resistance of cancer cells. Therefore, this study focused on the value of the DNA repair gene PARP1 and NF-κB pathway proteins in predicting the postoperative metastasis of breast cancer. A nested case‒control study was performed. Immunohistochemical methods were used to detect the expression of these genes in patients. ROC curves were used to analyse the predictive effect of these factors on distant metastasis. The COX model was used to evaluate the effects of PARP1 and TNF-α on distant metastasis. The results showed that the expression levels of PARP1, IKKβ, p50, p65 and TNF-α were significantly increased in the metastasis group (P < 0.001). PARP1 was correlated with IKKβ, p50, p65 and TNF-α proteins (P < 0.001). There was a correlation between IKKβ, p50, p65 and TNF-α proteins (P < 0.001). ROC curve analysis showed that immunohistochemical scores for PARP1 of > 6, IKKβ of > 4, p65 of > 4, p50 of > 2, and TNF-α of > 4 had value in predicting distant metastasis (SePARP1 = 78.35%, SpPARP1 = 79.38%, AUCPARP1 = 0.843; Sep50 = 64.95%, Spp50 = 70.10%, AUCp50 = 0.709; SeTNF-α = 60.82%, SpTNF-α = 69.07%, AUCTNF-α = 0.6884). Cox regression analysis showed that high expression levels of PARP1 and TNF-α were a risk factor for distant metastasis after breast cancer surgery (RRPARP1 = 4.092, 95% CI 2.475-6.766, P < 0.001; RRTNF-α = 1.825, 95% CI 1.189-2.799, P = 0.006). Taken together, PARP1 > 6, p50 > 2, and TNF-α > 4 have a certain value in predicting breast cancer metastasis, and the predictive value is better when they are combined for diagnosis (Secombine = 97.94%, Spcombine = 71.13%).

Network Pharmacology and Bioinformatics Analyses Identify the Core Genes and Pyroptosis-Related Mechanisms of Nardostachys Chinensis for Atrial Fibrillation

BACKGROUND

Nardostachys chinensis is an herbal medicine widely used in the treatment of atrial fibrillation (AF), but the mechanism is unclear.

OBJECTIVE

To explore the molecular mechanism of N. chinensis against AF.

METHODS

The TCMSP was used to screen the active N. chinensis compounds and their targets. Differentially expressed genes (DEGs) for AF were identified using open-access databases. Using Venn diagrams, the cross-targets of N. chinensis, pyroptosis, and AF were obtained. The genes underwent molecular docking as well as gene set enrichment analysis (GSEA). A nomogram based on candidate genes was constructed and evaluated with the clinical impact curve. After that, the immune infiltration of the dataset was analyzed by single sample GSEA (ssGSEA). Finally, microRNAs (miRNAs) and transcription factors (TFs) were predicted based on candidate genes.

RESULTS

Tumor necrosis factor (TNF) and caspase-8 (CASP8) were obtained as candidate genes by taking the intersection of DEGs, targets of N. chinensis, and pyroptosis-related genes. Tolllike receptor (TLR) and peroxisome proliferator-activated receptor (PPAR) signaling pathways were linked to candidate genes. Additionally, immune cell infiltration analysis revealed that CASP8 was associated with natural killer T cells, natural killer cells, regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSC), macrophages, CD8 T cells, and CD4 T cells. Finally, miR-34a-5p and several TFs were found to regulate the expression of CASP8 and TNF.

CONCLUSION

CASP8 and TNF are potential targets of N. chinensis intervention in pyroptosisrelated AF, and the TLR/NLRP3 signaling pathway may be associated with this process.

Cardiomyocyte and endothelial cells play distinct roles in the tumour necrosis factor (TNF)-dependent atrial responses and increased atrial fibrillation vulnerability induced by endurance exercise training in mice

AIMS

Endurance exercise is associated with an increased risk of atrial fibrillation (AF). We previously established that adverse atrial remodelling and AF susceptibility induced by intense exercise in mice require the mechanosensitive and pro-inflammatory cytokine tumour necrosis factor (TNF). The cellular and mechanistic basis for these TNF-mediated effects is unknown.

METHODS AND RESULTS

We studied the impact of Tnf excision, in either atrial cardiomyocytes or endothelial cells (using Cre-recombinase expression controlled by Nppa or Tie2 promoters, respectively), on the cardiac responses to six weeks of intense swim exercise training. TNF ablation, in either cell type, had no impact on the changes in heart rate, autonomic tone, or left ventricular structure and function induced by exercise training. Tnf excision in atrial cardiomyocytes did, however, prevent atrial hypertrophy, fibrosis, and macrophage infiltration as well as conduction slowing and increased AF susceptibility arising from exercise training. In contrast, endothelial-specific excision only reduced the training-induced atrial hypertrophy. Consistent with these cell-specific effects of Tnf excision, inducing TNF loss from atrial cardiomyocytes prevented activation of p38MAPKinase, a strain-dependent downstream mediator of TNF signalling, without affecting the atrial stretch as assessed by atrial pressures induced by exercise. Despite TNF's established role in innate immune responses and inflammation, neither acute nor chronic exercise training caused measurable NLRP3 inflammasome activation.

CONCLUSIONS

Our findings demonstrate that adverse atrial remodelling and AF vulnerability induced by intense exercise require TNF in atrial cardiomyocytes whereas the impact of endothelial-derived TNF is limited to hypertrophy modulation. The implications of the cell autonomous effects of TNF and crosstalk between cells in the atria are discussed.

Detection and modification of biomarkers of inflammation determining successful rhythm control in patients with atrial fibrillation

INTRODUCTION

Multiple pathophysiological mechanisms are involved in the pathogenesis of atrial fibrillation (AF). Growing evidence suggests that both local and systemic inflammation plays a key role even in early stages and its progression towards persisting and permanent AF. Rhythm control therapy via pulmonary vein isolation or cardioversion is the cornerstone of AF therapy for most symptomatic patients, yet arrhythmia recurrence after treatment is still common, especially in patients with persistent AF.

MATERIAL AND METHODS

In this review, we summarize the current state of knowledge of biomarkers of inflammation with prognostic value in patients with atrial fibrillation as well as anti-inflammatory medication with potential benefits after rhythm control therapy.

RESULTS AND DISCUSSION

Both onset of AF, progression and arrhythmia recurrence after rhythm control therapy can be caused by local and systemic inflammation. Various inflammatory biomarkers have been established to predict treatment success. Furthermore, additional anti-inflammatory therapy may significantly improve success rates.

Electrocardiogram Changes Following Intravenous Bisphosphonate Infusion: A Systematic Review and Meta-Analysis

Bisphosphonates are first-line treatments for several bone and mineral disorders. Studies have reported an increased incidence of serious atrial fibrillation in patients receiving bisphosphonates; however, uncertainty remains as to whether electrical disturbances are precipitated by bisphosphonates. We aimed to review the literature for studies reporting electrocardiogram (ECG) findings in patients receiving intravenous bisphosphonates for any indication. We searched MEDLINE and EMBASE from inception until January 14, 2023, for studies reporting ECG parameters after intravenous bisphosphonate infusion. We excluded studies that only reported atrial fibrillation. Study quality was assessed using the Newcastle-Ottawa scale. Continuous data were meta-analyzed if reported in at least two studies. Random-effects models were fitted and reported as standardized mean difference (SMD) with 95% confidence intervals (95% CIs). We found 1083 unique records, of which 11 met our inclusion and exclusion criteria. Studies had a low to low/moderate risk of bias. Six prospective cohort studies were included in the meta-analysis. Five studies used zoledronic acid, whereas one study used pamidronate. Most studies (n = 4) were conducted in postmenopausal women with osteoporosis, one study was conducted in patients with bone metastases, and one study in children with osteoporosis secondary to cerebral palsy. Study populations ranged from n = 15 to n = 116. Heart rate-corrected QT (QTc) was significantly longer post-infusion (SMD = 0.46 ms [95% CI 0.80 to 0.11]; n = 67 patients, k = 2 studies, τ2  = 0). There were no differences in heart rate, P wave (maximum), P wave (minimum), P wave dispersion, PR interval, QRS duration, QTc, QTc (maximum), QTc (minimum), and QTc dispersion. The correlation between pre- and post-infusion QTc was not significant (p = 0.93). Overall, there is a weak association between intravenous bisphosphonate infusion and a QTc interval prolongation. However, there is insufficient evidence to support an association between intravenous bisphosphonate and any ECG variable changes, which may precipitate atrial fibrillation. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Functional reserve and contractile phenotype of atrial myocardium from patients with atrial remodeling without and with atrial fibrillation

Atrial contractility and functional reserve in atrial remodeling (AR) without (AR/-AF) or with atrial fibrillation (AR/+AF) are not well characterized. In this study, functional measurements were performed in right atrial muscle strips (n = 71) obtained from patients (N = 22) undergoing routine cardiac surgery with either no AR [left atrial (LA) diameter < 40 mm and no history of AF (hAF)], AR/-AF (LA diameter ≥ 40 mm, no hAF), or AR/+AF (hAF and LA diameter ≥ 40 mm or LAEF < 45%). AR/-AF and AR/+AF were associated with a prolongation of half-time-to-peak (HTTP, P < 0.001) and time-to-peak (TTP) contraction (P < 0.01) when compared with no AR. This effect was seen at baseline and during β-adrenergic stimulation with isoproterenol (Iso). Early relaxation assessed by half-relaxation time (HRT) was prolonged in AR/-AF (P = 0.03) but not in AR/+AF when compared with no AR at baseline, but this delay in relaxation in AR/-AF was attenuated with Iso. Late relaxation (τ) did not differ between AR/-AF and no AR but was consistently shorter in AR/+AF than no AR before (P = 0.04) and during Iso (P = 0.01), indicating accelerated late relaxation in AR/+AF. Relative force increase during Iso was higher (P = 0.01) and more dispersed (P = 0.047) in patients with AR/+AF. Relative adrenergic response was unaltered in the myocardium of patients with AR/-AF and AR/+AF. In conclusion, AR/-AF and AR/+AF are associated with changes in myocardial inotropic reserve and contractility. The changes are particularly pronounced in patients with AR/+AF, suggesting that the progression from AR/-AF to AR/+AF is associated with progressive alterations in atrial function that may contribute to arrhythmogenesis.NEW & NOTEWORTHY Mechanical alterations in atrial remodeling without (AR/-AF) and with atrial fibrillation (AR/+AF) have not been studied in detail in human atrial tissue preparations. To our knowledge, this is the first study to compare the mechanical phenotype and inotropic reserve in human atrial myocardial preparations from patients with no atrial remodeling, AR/-AF, and AR/+AF. We identify specific patterns of contractile dysfunction and heterogeneity for both, AR/-AF and AR/+AF, indicating the progression of atrial disease.

The role of IL-6, IL-10, TNF-α and PD-1 expression on CD4 T cells in atrial fibrillation

Backgrounds

While not completely understood, the electrical, structural, and communication pathways that play a role in the onset and progression of atrial fibrillation (AF) seem to be connected to the intricate interplay between neurohormones and cellular mediators. Our study's objective was to examine how the expression profiles of the inflammatory cytokines interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor (TNF), and programmed death 1 (PD-1) changed in Cluster of Differentiation 4 (CD4) T cells depending on whether atrial fibrillation was paroxysmal or permanent. This analysis would provide new diagnostic markers for the detection and management of atrial fibrillation.

Methods

In a cross-sectional study, 60 healthy controls, 49 patients with persistent atrial fibrillation, and 50 patients with paroxysmal atrial fibrillation were compared. Serum biomarker levels are found using the ELISA method, which uses enzyme-linked immunosorbent assay. Echocardiography was used to assess heart function.

Results

Patients with atrial fibrillation had serum concentrations of IL-6, TNF-a, and IL-10 that were considerably higher than but PD-1 was lower those in the non-AF control group and those in patients with persistent atrial fibrillation. According to the diameter of LA and the serum level of NT-proB-type natriuretic peptide (NT-proBNP) is greater than that of patients with paroxysmal atrial fibrillation than control group. Patients with persistent atrial fibrillation had increased serum levels of low-density lipoprotein cholesterol (LDL-C) compared with those without atrial fibrillation. While PD-1 in patients with paroxysmal atrial fibrillation is closely related to C-reactive protein (CRP), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and very low density lipoprotein cholesterol. In addition, PD-1 in patients with persistent atrial fibrillation is closely related to IL-6, TNF-a, and IL-10.

Conclusion

Higher blood concentrations of NT-proBNP, IL-6, IL-10, TNF-, and LDL-C but low level of PD-1 are associated with progression from paroxysmal or chronic AF.

Tumor Necrosis Factor-α Mediates Inflammation-induced Early-Stage Left Ventricular Systolic Dysfunction

ABSTRACT

Elevated systemic inflammation contributes to pathogenesis of heart failure with preserved ejection fraction (HFpEF), but molecular mechanisms are poorly understood. Although left ventricular (LV) diastolic dysfunction is the main cause of HFpEF, subclinical systolic dysfunction also contributes. We have previously shown that rats with collagen-induced arthritis (CIA) have systemic inflammation, LV diastolic dysfunction, and that increased circulating TNF-α contributes to inflammation-induced HFpEF pathogenesis, but does not mediate LV diastolic dysfunction in CIA rats. Contribution of systemic inflammation to dysfunction of the active process of LV diastolic and systolic function are unknown. In the present study, we used the CIA rat model to investigate the effects of systemic inflammation and TNF-α blockade on systolic function, and mRNA expression of genes involved in active diastolic relaxation and of myosin heavy chain (MyHC) isoforms. Collagen inoculation and TNF-α blockade did not affect LV mRNA expression of genes that mediate active LV diastolic function. Collagen-induced inflammation impaired LV global longitudinal strain ( P = 0.03) and velocity ( P = 0.04). This impairment of systolic function was prevented by TNF-α blockade. Collagen inoculation decreased mRNA expression of α-MyHC ( Myh6, P = 0.03) and increased expression of β-MyHC ( Myh7, P = 0.0002), a marker, which is upregulated in failing hearts. TNF-α blockade prevented this MyHC isoform-switch. These results show that increased circulating TNF-α changes the relative expression of MyHC isoforms, favoring β-MyHC, which may underlie changes in contractile function that impair systolic function. Our results indicate that TNF-α initiates early-stage LV systolic, rather than LV diastolic dysfunction.

The Association Between Rheumatoid Arthritis and Atrial Fibrillation: Epidemiology, Pathophysiology and Management

Atrial fibrillation (AF) is the most common cardiac arrhythmia with a significant increase in morbidity and mortality worldwide. Rheumatoid arthritis (RA), as a systemic inflammatory disease, affecting 0.5-1.0% of the adult population, is associated with increased incidence of cardiac arrhythmias such as AF. Several epidemiologic studies find that the risk of AF is increased in RA when compared with the general population. Other studies are inconsistent. Considering that inflammation plays an important role in AF, RA may be involved in the occurrence and development of AF. This review summarizes the epidemiology, pathophysiology, and management of AF in patients with RA.

Evaluation of the association between circulating IL-1β and other inflammatory cytokines and incident atrial fibrillation in a cohort of postmenopausal women

BACKGROUND

Inflammatory cytokines play a role in atrial fibrillation (AF). Interleukin (IL)-1β, which is targeted in the treatment of ischemic heart disease, has not been well-studied in relation to AF.

METHODS

Postmenopausal women from the Women's Health Initiative were included. Cox proportional hazards regression models were used to evaluate the association between log-transformed baseline cytokine levels and future AF incidence. Models were adjusted for body mass index, age, race, education, hypertension, diabetes, hyperlipidemia, current smoking, and history of coronary heart disease, congestive heart failure, or peripheral artery disease.

RESULTS

Of 16,729 women, 3,943 developed AF over an average of 8.5 years. Racial and ethnic groups included White (77.4%), Black/African-American (16.1%), Asian (2.7%), American Indian/Alaska Native (1.0%), and Hispanic (5.5%). Baseline IL-1β log continuous levels were not significantly associated with incident AF (HR 0.86 per 1 log [pg/mL] increase, P= .24), similar to those of other inflammatory cytokines, IL-7, IL-8, IL-10, IGF-1, and TNF-α. There were significant associations between C-reactive protein (CRP) and IL-6 with incident AF.

CONCLUSIONS

In this large cohort of postmenopausal women, there was no significant association between IL-1β and incident AF, although downstream effectors, CRP and IL-6, were associated with incident AF.

Evaluation of New Potential Inflammatory Markers in Patients with Nonvalvular Atrial Fibrillation

Atrial fibrillation (AF), the most common arrhythmia in clinical practice, is associated with an increase in mortality and morbidity due to its high potential to cause stroke and systemic thromboembolism. Inflammatory mechanisms may play a role in the pathogenesis of AF and its maintenance. We aimed to evaluate a range of inflammatory markers as potentially involved in the pathophysiology of individuals with nonvalvular AF (NVAF). A total of 105 subjects were enrolled and divided into two groups: patients with NVAF (n = 55, mean age 72 ± 8 years) and a control group of individuals in sinus rhythm (n = 50, mean age 71 ± 8 years). Inflammatory-related mediators were quantified in plasma samples by using Cytometric Bead Array and Multiplex immunoassay. Subjects with NVAF presented significantly elevated values of interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF), interferon-gamma, growth differentiation factor-15, myeloperoxidase, as well as IL-4, interferon-gamma-induced protein (IP-10), monokine induced by interferon-gamma, neutrophil gelatinase-associated lipocalin, and serum amyloid A in comparison with controls. However, after multivariate regression analysis adjusting for confounding factors, only IL-6, IL-10, TNF, and IP-10 remained significantly associated with AF. We provided a basis for the study of inflammatory markers whose association with AF has not been addressed before, such as IP-10, in addition to supporting evidence about molecules that had previously been associated with the disease. We expect to contribute to the discovery of markers that can be implemented in clinical practice hereafter.

Risk factors, thromboembolic events, and clinical course of New-Onset Atrial Fibrillation among COVID-19 hospitalized patients: A multicenter cross-sectional analysis in Iran

Background and Aims

We focused on determining the risk factors, thromboembolic events, and clinical course of New-Onset Atrial Fibrillation (NOAF) among hospitalized coronavirus disease (COVID-19) patients.

Methods

This retrospective study was conducted in the major referral centers in Tehran, Iran. Of 1764 patients enrolled in the study from January 2020 until July 2021, 147 had NOAF, and 1617 had normal sinus rhythm. Univariate and multivariate Logistic regressions were employed accordingly to evaluate NOAF risk factors. The statistical assessments have been run utilizing SPSS 25.0 (SPSS) or R 3.6.3 software.

Results

For the NOAF patients, the age was significantly higher, and the more prevalent comorbidities were metabolic syndrome, heart failure (HF), peripheral vascular disease, coronary artery disease, and liver cirrhosis. The multivariate analysis showed the established independent risk factors were; Troponin-I (hazard ratio [HR] = 3.86; 95% confidence interval [CI] = 1.89-7.87; p < 0.001), HF (HR = 2.54; 95% CI = 1.61-4.02; p < 0.001), bilateral grand-glass opacification (HR = 2.26; 95% CI = 1.68-3.05; p = 0.002). For cases with thromboembolic events, NOAF was the most important prognostic factor (odds ratio [OR] = 2.97; 95% CI = 2.03-4.33; p < 0.001). While evaluating the diagnostic ability of prognostic factors in detecting NOAF, Troponin-I (Area under the curve [AUC] = 0.85), C-Reactive Protein (AUC = 0.72), and d-dimer (AUC = 0.65) had the most accurate sensitivity. Furthermore, the Kaplan-Meier curves demonstrated that the survival rates diminished more steeply for patients with NOAF history.

Conclusion

In hospitalized COVID-19 patients with NOAF, the risk of thromboembolic events, hospital stay, and fatality are significantly higher. The established risk factors showed that patients with older age, higher inflammation states, and more severe clinical conditions based on CHADS2VASC-score potentially need subsequent preventive strategies. Appropriate prophylactic anticoagulants, Initial management of cytokine storm, sufficient oxygen support, and reducing viral shedding could be of assistance in such patients.

Inflammatory cytokines differ between patients with high versus low CHA2DS2-VASc scores in sinus rhythm-a possible mechanism for adverse cardiovascular events

Background

The CHA₂DS₂-VASc score was shown to predict systemic thromboembolism and mortality in certain groups of patients in sinus rhythm (SR). Previous data showed that patients in SR with high CHA₂DS₂-VASc score have higher plasma levels of inflammatory markers such as sP-selectin and C-reactive protein. We further investigated this group.

Methods

Blood samples were collected from consecutive patients in SR. Plasma was extracted and stored at -80 °C. Concentrations of a panel of soluble markers IL-1β, IL-6, IL-8, IL-10, TNF-α and VEGF were measured by Magnetic Luminex Performance Assay. The PLF4 cytokine blood level was measured by ELISA.

Results

66 patients were enrolled (age 53 ± 18 years, 60% women). Patients with high CHA₂DS₂-VASc scores (n = 23) had significantly higher median IQR concentrations of TNF-α [10.34 (8.55,14.92) vs. 7.69 (6.06, 9.85) pg/ml, p = 0.009] and a trend towards higher levels of IL-1β [0.59 (0.4,0.8) vs. 0.44 (0.31, 0.62) pg/ml, p = 0.07] and IL-8 [5.92 (4.5,9.4) vs. 5.04 (3.63, 6.04) pg/ml, p = 0.07], compared to the group with low scores (n = 43). Median IQR concentrations of VEGF, IL-6, IL-10 and PF4 did not significantly differ between the CHA₂DS₂-VASc score groups.

Conclusion

Patients in SR with high versus low CHA₂DS₂-VASc scores have high plasma concentrations of systemic inflammation cytokines. The already proven high levels of sP-selectin, that promotes release of inflammatory cytokines from leukocytes, is in line with these results. This pro-inflammatory state in patients with high CHA₂DS₂-VASc scores, may explain the higher rate of adverse cardiovascular events associated with elevated CHA₂DS₂-VASc score even without atrial fibrillation.

Risk Factors of Early Atrial Fibrillation Recurrence Following Electrical Cardioversion When Left Ventricular Ejection Fraction Is Preserved

Background and objectives: To identify clinical, echocardiographic, and laboratory parameters that affect the early recurrence of atrial fibrillation (AF) after restoring sinus rhythm (SR) by electrical cardioversion (ECV), and to determine whether left atrial (LA) strain, as a noninvasive indicator reflecting fibrosis, is associated with laboratory indicators affecting the development of fibrosis, interleukin 6 (IL-6) or tumor necrosis factor α (TNF-α). Materials and Methods: The study included 92 persistent AF patients who underwent elective ECV. The effective maintenance of SR was evaluated after 40 ± 10 days of ECV. Echocardiography, inflammatory markers (high-sensitivity c-reactive protein (hs-CRP), IL-6, and TNF-α), and natriuretic peptides (N-terminal pro b-type natriuretic peptide (NT-proBNP) and N-terminal pro a-type natriuretic peptide (NT-proANP)) were assessed. Results: After a 40 ± 10 days observation period, 51 patients (55.4%) were in SR. Patients with AF recurrence had a significantly longer duration of AF (p = 0.008) and of arterial hypertension (p = 0.035), lower LA ejection fraction (p = 0.009), lower LA strain (p < 0.0001), higher left ventricular global longitudinal strain (p = 0.001), and a higher E/e‘ ratio (p < 0.0001). LA strain was an independent predictor of early AF recurrence (OR: 0.65; 95% Cl 0.5−0.9, p = 0.004). LA strain < 11.85% predicted AF recurrence with 70% sensitivity and 88% specificity (AUC 0.855, 95% CI 0.77−0.94, p < 0.0001). LA strain demonstrated the association with NT-proBNP (r = −0.489, p < 0.0001) and NT-proANP (r = −0.378, p = 0.002), as well as with hs-CRP (r = −0.243, p = 0.04). Conclusions: LA strain appeared to be the most accurate predictor of early AF recurrence after ECV in patients with persistent AF. LA strain inversely correlated with NT-proBNP and NT-proANP, but no significant association with any of the inflammatory markers was identified.

Atrial electromechanical delay is impaired in patients with COVID-19

Background: COVID-19 infection has the potential to affect the cardiovascular system. Intra/ interatrial electromechanical delay (EMD) demonstrated by P wave dispersion (PD) and tissue doppler echocardiography (TDE) is related to the development of atrial fibrillation. This study aimed to investigate atrial conduction time by PD and TDE in patients with COVID-19. Material and Method: A total of 143 participants were selected in the current study. The COVID-19 group included 90 subjects and the control group included 53 individuals. Two groups were compared with each other, in terms of electrocardiographic P wave measurements, and atrial electromechanical coupling (AEC) parameters by TDE. Results: Maximum P-wave duration (Pmax) and PD were significantly higher in COVID-19 patients compared to the control group (p

Identification of genes and key pathways underlying the pathophysiological association between nonalcoholic fatty liver disease and atrial fibrillation

Background

Atrial fibrillation (AF) is one of the most prevalent sustained cardiac arrhythmias. The latest studies have revealed a tight correlation between nonalcoholic fatty liver disease (NAFLD) and AF. However, the exact molecular mechanisms underlying the association between NAFLD and AF remain unclear. The current research aimed to expound the genes and signaling pathways that are related to the mechanisms underlying the association between these two diseases.

Materials and methods

NAFLD- and AF- related differentially expressed genes (DEGs) were identified via bioinformatic analysis of the Gene Expression Omnibus (GEO) datasets GSE63067 and GSE79768, respectively. Further enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), the construction of a protein–protein interaction (PPI) network, the identification of significant hub genes, and receiver operator characteristic curve analysis were conducted. The gene-disease interactions were analyzed using the Comparative Toxicogenomics Database. In addition, the hub genes were validated by quantitative Real-Time PCR (qRT-PCR) in NAFLD cell model.

Results

A total of 45 co-expressed differentially expressed genes (co-DEGs) were identified between the NAFLD/AF and healthy control individuals. GO and KEGG pathway analyses revealed that the co-DEGs were mostly enriched in neutrophil activation involved in the immune response and cytokine-cytokine receptor interactions. Moreover, eight hub genes were selected owing to their high degree of connectivity and upregulation in both the NAFLD and AF datasets. These genes included CCR2, PTPRC, CXCR2, MNDA, S100A9, NCF2, S100A12, and S100A8.

Conclusions

In summary, we conducted the gene differential expression analysis, functional enrichment analysis, and PPI analysis of DEGs in AF and NAFLD, which provides novel insights into the identification of potential biomarkers and valuable therapeutic leads for AF and NAFLD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01300-1.

Quizalofop-P-ethyl induced developmental toxicity and cardiotoxicity in early life stage of zebrafish (Danio rerio)

Quizalofop-P-ethyl (QpE), a highly efficient selective herbicide, has good control effect on annual and perennial weeds. However, its excessive use will pose a threat to the ecological environment. QpE has been proven harmful to aquatic organisms, but there is little evidence on the adverse effects of QpE in the early life of aquatic organisms. In this work, zebrafish (Danio rerio) embryos were treated with 0.10, 0.20, 0.30, 0.40, and 0.50 mg/L of QpE for 120 h. The findings revealed that the LC₅₀ value of QpE to zebrafish embryos was 0.23 mg/L at 96 hpf. QpE exposure significantly increased the mortality rate, decreased the hatching rate and caused morphological defects during zebrafish embryonic development, with a concentration dependent manner. QpE also caused severe morphological changes in the cardiovascular system, as well as resulted in a dysfunction in cardiovascular performance. Meanwhile, both histopathological examination and neutrophil observations showed inflammatory response occurred in the heart. Furthermore, several genes associated with heart development and inflammation were significantly altered following QpE exposure. A protein-protein interaction (PPI) network analysis proved that there was a connection between the changed heart development-relevant and inflammation-related genes. Taken together, our findings suggest that QpE causes cardiotoxicity in zebrafish embryos by altering the expression of genes in the regulatory network of cardiac development, which might be aggravated by inflammatory reactions, thereby affecting embryo development. These findings generated here are useful for in-depth assessment of the effects of QpE on early development of aquatic organisms and providing theoretical foundation for risk management measures.

Bidirectional Association Between Kidney Function and Atrial Fibrillation: A Population-Based Cohort Study

Background Consensus lacks concerning a bidirectional association between kidney function and atrial fibrillation (AF), but this is crucial information for prevention/treatment efforts for both chronic kidney disease and AF. Therefore, we investigated the bidirectional association between kidney function and AF. Methods and Results This study was a prospective cohort study including 9228 participants (mean age, 64.9 years; 57.2% women) with information on kidney function (estimated glomerular filtration rate [eGFR] based on serum creatinine [eGFRcreat], cystatin C [eGFRcys], or both [eGFRcreat-cys], and urine albumin-to-creatinine ratio) and AF. Reduced kidney function was defined as eGFRcreat <60 mL/min per 1.73 m². Cox proportional-hazards, logistic regression, linear mixed, and joint models were used to investigate the association of kidney function with AF and vice versa. During follow-up (median of 8.0 years), 780 events of incident AF occurred. Lower eGFRcys and eGFRcreat-cys were associated with increased AF risk (hazard ratio [HR], 1.08 [95% CI, 1.03-1.14] and HR, 1.07 [95% CI, 1.01-1.14], respectively, per 10 mL/min per 1.73 m² eGFR decrease). For eGFRcys and eGFRcreat-cys, 10-year cumulative incidence of AF was 16% (eGFR <60) and 6% (eGFR ≥60). Prevalent AF (versus no prevalent AF) was associated with 2.85 mL/min per 1.73 m² lower eGFRcreat and with a faster decline of eGFRcreat with age. Prevalent AF was associated with a 1.3-fold increased risk of incident reduced kidney function. Conclusions Kidney function, especially eGFRcys, and AF are bidirectionally associated. There are currently no targeted prevention efforts for AF in patients with mild chronic kidney disease and vice versa. Our results could provide the first step to improve prediction/prevention of both conditions.

Prednisone Ameliorates Atrial Inflammation and Fibrosis in Atrial Tachypacing Dogs

Atrial inflammation and fibrosis have long been considered culprits in the development of atrial fibrillation (AF). Prior clinical studies showed that corticosteroid therapy is beneficial in patients with AF. Here we sought to determine whether prednisone treatment prevents atrial tachypacing (ATP) induced atrial fibrosis.Dogs were randomized into the sham, ATP, ATP + low-dose prednisone (ALP), and ATP + high-dose prednisone (AHP) groups. After 6 days of recovery from surgery, dogs were subjected to ATP at 400 beats per minute for 4 weeks while being treated with prednisone (15 or 40 mg/day) or a placebo. Pacemakers were not activated in the sham group.Compared with the ATP group, the expression of collagen I, collagen III, α-smooth muscle actin, transforming growth factor-β1 and connective tissue growth factor were significantly reduced in the ALP and AHP groups. Fluorescence assays showed that reactive oxygen species formation in the right atrium was suppressed in the ALP and AHP groups compared with the ATP group. The protein level of NADPH oxidase 2 was reduced in the ALP and AHP groups' versus ATP group, while NOX4 and NOX5 were unchanged. ATP-induced downregulation of BH4 and eNOS uncoupling in the atria was partially restored in the prednisone-treated groups.Our study demonstrated that atrial fibrosis induced by ATP were suppressed by prednisone. Low-dose prednisone was also effective in suppressing the development of atrial fibrosis.

Biomarkers of Metabolic Syndrome: Role in Pathogenesis and Pathophysiology Of Atrial Fibrillation

The relationship between Metabolic syndrome and Atrial Fibrillation is confirmed by many studies. The components of Metabolic syndrome cause remodeling of the atrial. Metabolic syndrome and metabolic derangements of the syndrome could be the cause of the pathogenesis of AF. This review article discusses the major biomarkers of Metabolic syndrome and their role in the pathogenesis of AF. The biomarkers are adiponectin, leptin, Leptin/ Adiponectin ratio, TNF-α, Interleukin-6, Interleukin-10, PTX3, ghrelin, uric acid, and OxLDL.The elevated plasma levels of adiponectin were linked to the presence of persistent AF. Leptin signaling contributes to angiotensin-II evoked AF and atrial fibrosis. Tumor necrosis factor-alpha involvement has been shown in the pathogenesis of chronic AF. Similarly, Valvular AF patients showed high levels of TNF-α. Increased left atrial size was associated with the interleukin-6 because it is a well-known risk factor for AF. Interleukin-10 as well as TNF-α were linked to AF recurrence after catheter ablation. PTX3 could be superior to other inflammatory markers that were reported to be elevated in AF. The serum ghrelin concentration in AF patients was reduced and significantly increased after treatment. Elevated levels of uric acid could be related to the burden of AF. Increased OxLDL was found in AF as compared to sinus rhythm control.

Anti-inflammatory HDL effects are impaired in atrial fibrillation

High-density lipoprotein (HDL), best known for cholesterol transport, also has anti-inflammatory effects. Previous studies suggest involvement of myeloperoxidase (MPO) in modification of HDL. HDL bound Sphingosine-1-phosphate (S1P) has been implied to be an essential protein regarding beneficial HDL effects. In this study, we analyzed anti-inflammatory HDL properties in patients with atrial fibrillation (AF), a disease involving atrial inflammation, compared to non-AF controls and whether anti-inflammatory properties improve upon catheter ablation. Additionally, association with serum concentrations of MPO and S1P were assessed. We isolated HDL from 25 AF patients, 13 non-AF individuals and 14 AF patients at follow-up (FU) after catheter ablation. S1P was measured in a cohort of 141 AF and 21 FU patients. Following preincubation with HDL from either group, bovine aortic endothelial cells were stimulated using tumor necrosis factor α and expression of pro-inflammatory genes intercellular adhesion molecule 1 (ICAM1), vascular cell adhesion molecule 1 (VCAM1), E-selectin (SELE) and P-selectin (SELP) was assessed using qPCR. Concentrations of circulating protein of these genes as well as MPO and S1P were measured in serum samples. Compared to non-AF individuals HDL from AF patients suppressed gene expression of the pro-inflammatory adhesion molecules ICAM1, VCAM1, SELE and SELP 27%, 18%, 21% and 57% less, respectively (p < 0.05 for all except SELE p = 0.06). In FU patients, the anti-inflammatory HDL activity was improved (suppression of ICAM1 + 22%, VCAM1 + 10%, SELE + 38% and SELP + 75%, p < 0.05 for all except VCAM1 p = 0.08). AF patients using angiotensin converting enzyme inhibitors or angiotensin receptor blockers had better anti-inflammatory HDL properties than non-users (gene expression suppression at least 28% more, p < 0.05 for all except ICAM1 p = 0.051). Circulating protein concentrations were not correlated with in vitro gene-expression, but circulating P-selectin was generally elevated in AF and FU patients compared to non-AF patients. MPO plasma concentration was positively associated with gene-expression of ICAM1, VCAM1 and SELP (r² > 0.4, p < 0.05). Serum concentrations of S1P were increased in FU patients {1.201 µM [1.077–1.543]} compared to AF patients {0.953 µM [0.807–1.135], p < 0.01} but not correlated with ICAM1, VCAM1 and SELP gene expression. We conclude that the anti-inflammatory activity of HDL is impaired in AF patients, which might promote AF progression and AF-associated complications.

Role of inflammation in atrial fibrillation: A comprehensive review of current knowledge

BACKGROUND

Atrial fibrillation (AF) is one of the most common cardiac disorders affecting adults and is associated with significant morbidity and mortality. Efforts to manage AF through anti-arrhythmics and rate control have been largely unsatisfactory. It has become clear that AF causes structural alterations in the atrial myocardium that propagate further AF, and that some of these alterations are the result of inflammation.

METHODS

An in-depth review of the available literature was undertaken using Google Scholar and keyword searches including [Atrial fibrillation] in combination with [inflammatory markers], [myocardial fibrosis], and [immunomodulators], limiting the search to English language articles. All articles were reviewed for relevance and collated by the author.

RESULTS

Multiple markers of inflammation have been shown to be elevated in AF and to predict responses to treatments of AF including anti-arrhythmics and cardioversion. The nidus of inflammation is not clear but seems to be related to the pulmonary veins.

CONCLUSIONS

The inflammatory cascade induces fibrotic changes in the myocardium, an arrhythmogenic process that stimulates further inflammation. Advances in treatment are focusing on biological agents and immunomodulators that inhibit the inflammatory cascade.

New onset atrial fibrilation and risk faktors in COVID-19

BACKGROUND

There is limited data concerning the prevalence of arrhythmias, particularly atrial fibrillation (AF), which may develop as a consequence of direct myocardial injury and the inflammatory state existing in COVID-19.

METHODS

This single-center study included data concerning 658 COVID-19 patients, who were hospitalized in our institute, between April 20th, 2020 and July 30th, 2020. Demographic data, findings of the imaging studies, and laboratory test results were retrieved from the institutional digital database.

RESULTS

New onset AF (NOAF) was identified in 33 patients (5%). Patients who developed AF were older (72.42 ± 6.10 vs 53.78 ± 13.80, p < 0.001) and had higher frequencies of hypertension and heart failure compared to patients without NOAF (p < 0.001, for both). The CHA2DS2-VASc score was higher in patients, who developed NOAF, compared to those who did not during hospitalization for COVID-19 (p < 0.001). Subjects, who developed NOAF during hospitalization, had a higher leukocyte count, neutrophil / lymphocyte ratio (NLR), C-reactive protein, erythrocyte sedimentation rate, and procalcitonin levels compared to those without NOAF (p < 0.001 for all comparisons). Diffuse lung infiltration was also more frequent in COVID-19 patients, who developed NOAF, during hospitalization (p = 0.015). Multivariate logistic regression analysis demonstrated that age, CHA2DS2-VASc score, CRP, erythrocyte sedimentation rate, and presence of diffuse lung infiltration on thorax CT were predictive for NOAF.

CONCLUSION

The prevalence of NOAF in hospitalized COVID-19 patients is higher than the general population. Age, CHA2DS2-VASc score, C-reactive protein, erythrocyte sedimentation rate, and presence of diffuse lung infiltration on thorax CT may be used to identify patients at high risk for development of NOAF. Especially among these parameters, the presence of diffuse lung infiltration on thorax CT it was the most powerful independent predictor of NOAF development.

Transcriptomic Bioinformatic Analyses of Atria Uncover Involvement of Pathways Related to Strain and Post-translational Modification of Collagen in Increased Atrial Fibrillation Vulnerability in Intensely Exercised Mice

Atrial Fibrillation (AF) is the most common supraventricular tachyarrhythmia that is typically associated with cardiovascular disease (CVD) and poor cardiovascular health. Paradoxically, endurance athletes are also at risk for AF. While it is well-established that persistent AF is associated with atrial fibrosis, hypertrophy and inflammation, intensely exercised mice showed similar adverse atrial changes and increased AF vulnerability, which required tumor necrosis factor (TNF) signaling, even though ventricular structure and function improved. To identify some of the molecular factors underlying the chamber-specific and TNF-dependent atrial changes induced by exercise, we performed transcriptome analyses of hearts from wild-type and TNF-knockout mice following exercise for 2 days, 2 or 6 weeks of exercise. Consistent with the central role of atrial stretch arising from elevated venous pressure in AF promotion, all 3 time points were associated with differential regulation of genes in atria linked to mechanosensing (focal adhesion kinase, integrins and cell-cell communications), extracellular matrix (ECM) and TNF pathways, with TNF appearing to play a permissive, rather than causal, role in gene changes. Importantly, mechanosensing/ECM genes were only enriched, along with tubulin- and hypertrophy-related genes after 2 days of exercise while being downregulated at 2 and 6 weeks, suggesting that early reactive strain-dependent remodeling with exercise yields to compensatory adjustments. Moreover, at the later time points, there was also downregulation of both collagen genes and genes involved in collagen turnover, a pattern mirroring aging-related fibrosis. By comparison, twofold fewer genes were differentially regulated in ventricles vs. atria, independently of TNF. Our findings reveal that exercise promotes TNF-dependent atrial transcriptome remodeling of ECM/mechanosensing pathways, consistent with increased preload and atrial stretch seen with exercise. We propose that similar preload-dependent mechanisms are responsible for atrial changes and AF in both CVD patients and athletes.

The Effect of Dapagliflozin Treatment on Epicardial Adipose Tissue Volume and P-Wave Indices: An Ad-hoc Analysis of The Previous Randomized Clinical Trial

AIM

Epicardial adipose tissue (EAT) may be associated with arrhythmogenesis. P-wave indices such as P-wave dispersion and P-wave variation indicated a slowed conduction velocity within the atria. This study investigated the effect of dapagliflozin on EAT volume and P-wave indices.

METHODS

In the present ad hoc analysis, 35 patients with type 2 diabetes mellitus and coronary artery disease were classified into dapagliflozin group (n=18) and conventional treatment group (n=17). At baseline, EAT volume, HbA1c and plasma level of tumor necrotic factor-α (TNF-α) levels, echocardiography, and 12-lead electrocardiogram (ECG) were performed. EAT volume was measured using computed tomography. Using 12-lead ECG, P-wave indices were measured.

RESULTS

At baseline, EAT volumes in the dapagliflozin and conventional treatment groups were 113±20 and 110±27 cm3, respectively. Not only HbA1c and plasma level of TNF-α but also echocardiography findings including left atrial dimension and P-wave indices were comparable between the two groups. After 6 months, plasma level of TNF-α as well as EAT volume significantly decreased in the dapagliflozin group only. P-wave dispersion and P-wave variation significantly decreased in the dapagliflozin group only (-9.2±8.7 vs. 5.9±19.9 ms, p=0.01; -3.5±3.5 vs. 1.7±5.9 ms, p=0.01). The change in P-wave dispersion correlated with changes in EAT volume and plasma level of TNF-α. In multivariate analysis, the change in EAT volume was an independent determinant of the change in P-wave dispersion.

CONCLUSION

Dapagliflozin reduced plasma level of TNF-α, EAT volume, and P-wave indices, such as P-wave dispersion. The changes in P-wave indices were especially associated with changes in EAT volume.The number and date of registration: UMIN000035660, 24/Jan/2019.

Selective blocking of CXCR2 prevents and reverses atrial fibrillation in spontaneously hypertensive rats

Atrial fibrillation (AF) is associated with inflammation and oxidative stress. Recently, we demonstrated that the chemokine‐receptor CXCR2 plays a critical role in the recruitment of monocytes/macrophages and the development of hypertension and cardiac remodelling. However, the role of CXCR2 in the pathogenesis of hypertensive AF remains unclear. AF was induced in Wistar‐Kyoto rats (WKYs) and spontaneously hypertensive rats (SHRs) administered with the CXCR2 inhibitor SB225002. Atrial remodelling, pathological changes and electrophysiology were examined. Our results showed that the chemokine CXCL1 and its receptor CXCR2 were markedly increased in atrial tissue of SHRs compared with WKYs. The administration of SB225002 to SHRs significantly reduced the elevation of blood pressure, AF inducibility and duration, atrial remodelling, recruitment of macrophages, superoxide production and conduction abnormalities compared with vehicle treatment. The administration of SB225002 to SHRs also reversed pre‐existing AF development, atrial remodelling, inflammation and oxidative stress. These effects were associated with the inhibition of multiple signalling pathways, including TGF‐β1/Smad2/3, NF‐κB‐P65, NOX1, NOX2, Kir2.1, Kv1.5 and Cx43. In conclusion, this study provides new evidence that blocking CXCR2 prevents and reverses the development of AF in SHRs, and suggests that CXCR2 may be a potential therapeutic target for hypertensive AF.

Inflammatory activation and endothelial dysfunction markers in patients with permanent atrial fibrillation: a cross-sectional study

In recent years a growing body of evidence supported the role of inflammation in the initiation, maintenance and outcome of atrial fibrillation (AF). Nevertheless, despite a large amount of information, whether AF or the underlying structural heart disease (SHD) is the cause of the inflammatory process is still under debate. We, therefore, sought to determine if the inflammatory process reflect an underlying disease or the arrhythmia ‘per se’. We evaluated plasma levels of soluble Interleukin 2 Receptor Alpha (sIL-2Rα), TNF-α and IL-18 in 100 consecutive patients with permanent AF, (43 with a SHD and 57 without a SHD) compared to 121 age and sex-matched controls which had normal sinus rhythm. We also evaluated the endothelial function in both groups of patients using reactive hyperemia index (RHI) values measured by Endo-PAT2000. Compared to controls, AF patients showed higher circulating levels of inflammatory markers and a lower mean value of RHI. At multiple logistic regression analysis, the inflammatory markers and RHI were significantly associated with AF presence, whereas ROC curve analysis had good sensitivity and specificity in inflammatory variables and RHI for AF presence. No significant association was observed in the group of permanent AF patients, between inflammatory markers and the presence of an underlying SHD. These findings could help to clarify the role of inflammation in subjects with AF and suggest that the markers of systemic inflammation are not associated with the underlying cardiovascular disease, rather with the atrial fibrillation ‘per se’.

High hydrostatic pressure induces atrial electrical remodeling through upregulation of inflammatory cytokines

AIMS

Hypertension is an independent risk factor for atrial fibrillation (AF). However, the direct effect of hydrostatic pressure on atrial electrical remodeling is unclear. The present study investigated whether hydrostatic pressure is responsible for atrial electrical remodeling and addressed a potential role of inflammation in this pathology.

MAIN METHODS

Whole-cell patch-clamp recordings and biochemical assays were used to study the regulation and expression of ion channels in left atrial appendages in patients with AF, spontaneously hypertensive rats (SHRs), and atrium-derived cells (HL-1 cells) exposed to standard (0 mmHg) and elevated (20, 40 mmHg) hydrostatic pressure.

KEY FINDINGS

Both TNF-α and MIF were highly expressed in patients with AF and SHRs. AF inducibility in SHRs was higher after atrial burst pacing, accompanied by a decrease in the L-type calcium current (I_Ca,L), an increase in the transient outward K⁺ current (I_to) and ultra-rapid delayed rectifier K⁺ current (I_Kur), and a shortened action potential duration (APD), which could be inhibited by atorvastatin. Furthermore, exposure to elevated pressure was associated with electrical remodeling of the HL-1 cells. The peak current density of I_Ca,L was reduced, while I_to and I_Kur were increased. Moreover, the expression levels of Kv4.3, Kv1.5, TNF-α, and MIF were upregulated, while the expression of Cav1.2 was downregulated in HL-1 cells after treatment with high hydrostatic pressure (40 mmHg). Atorvastatin alleviated the electrical remodeling and increased inflammatory markers in HL-1 cells induced by high hydrostatic pressure.

SIGNIFICANCE

Elevated hydrostatic pressure led to atrial electrical remodeling and increased AF susceptibility by upregulating inflammation.

Association study of a functional variant of TNF-α gene and serum TNF-α level with the susceptibility of congenital heart disease in a Chinese population

BACKGROUND

Congenital heart disease (CHD) is among the leading causes of infant death worldwide. Although shortage of folate has been found potentially to contribute to CHD in the embryo, the aetiology of CHD was not completely understood. Inflammation and altered immune processes are involved in all forms of cardiac malformation, including CHD. Tumour necrosis factor-α (TNF-α), was involved in the pathogenesis of multiple kinds of heart diseases. However, no studies have systematically evaluated the associations of genetic variants of TNF-α with susceptibility of CHD.

METHODS

A case-control study was conducted to evaluate the associations between tagSNPs of TNF-α and CHD susceptibility. Serum level of TNF-α was assessed using ELISA. The dual luciferase reporter assay was used to evaluate the functional significance of variant rs1800629 on TNF-α transcriptional activity.

RESULTS

We found rs1800629 was significantly correlated with increased CHD susceptibility (OR: 1.72, 95% CI 1.26 to 2.36, p=0.001). Serum levels of TNF-α were significantly higher in CHD group (9.09±1.90 pg/mL) than that in control group (6.12±1.56 pg/mL, p<0.001). The AA genotype and AG genotype of rs1800629 was associated with higher serum TNF-α level, compared with GG genotype. The dual luciferase reporter assay showed that promoter activity was significantly increased by 57% and 76% for plasmids containing the minor A allele compared with the major G allele in H9c2 and HEK 293T, respectively.

CONCLUSION

These results indicate that higher level of serum TNF-α increases risk of CHD, while TNF-α rs1800629 A allele might contribute to higher risk for CHD due to the increase in TNF-α expression.

Median nerve stimulation prevents atrial electrical remodelling and inflammation in a canine model with rapid atrial pacing

Aims

Studies have shown that stellate ganglion nerve activity has association with atrial electrical remodelling and atrial fibrillation (AF) inducibility, while median nerve stimulation (MNS) decreases cardiac sympathetic drive. In this study, we tested the hypothesis that MNS suppresses atrial electrical remodelling and AF vulnerability.

Methods and results

The atrial effective refractory period (AERP) and AF inducibility at baseline and after 3 h of rapid atrial pacing were determined in dogs undergoing MNS (n = 7), MNS+ application of methyllycaconitine (n = 7) or sham procedure (n = 6). Then, the levels of tumour necrosis factor-alpha (TNF-a), interleukin-6 (IL-6), and acetylcholine (Ach) in the plasma and atrial tissues were measured. The control dogs (n = 4) were assigned to measure atrial inflammation cytokines. Short-term rapid atrial pacing induced shortening of the AERP, an increase in AERP dispersion, and an increase AF vulnerability in the sham dogs, which were all suppressed by MNS. Levels of TNF-a and IL-6 were higher, and Ach levels were lower in the left and the right atrium in the sham dogs than in the MNS dogs. Methyllycaconitine blunted the effects of MNS on the AERP, AERP dispersion, the AF vulnerability, and TNF-a and IL-6 levels in the atrium, but had no impact on the levels of Ach.

Conclusions

The effects of MNS on atrial electrical remodelling and AF inducibility might be associated with the cholinergic anti-inflammatory pathway.

Single and persistent elevation of C-reactive protein levels and the risk of atrial fibrillation in a general population: The Ansan-Ansung Cohort of the Korean Genome and Epidemiology Study

BACKGROUND

Inflammation has been reported to cause atrial fibrillation (AF). However, it remains unclear whether C-reactive protein (CRP) levels predict AF. We investigated whether there was an association between serum CRP levels and the development of AF.

METHODS

A total of 10,030 subjects aged between 40 and 69 years were enrolled and followed biennially over a 12-year period in the Ansan-Ansung cohort study. Serum CRP levels were measured at baseline and high-sensitivity CRP (hsCRP) levels were measured at every revisit. AF was identified using 12-lead standard electrocardiography. Inverse probability of treatment weighting was applied to balance the confounders of AF development between groups.

RESULTS

Serum CRP levels were higher in subjects with AF at baseline and those with new-onset AF than in those without AF. Cox-regression analysis showed that high CRP levels (>3 mg/L) and intermediate CRP levels (1-3 mg/L) at baseline were not associated with a higher risk of new-onset AF compared with low CRP levels (<1 mg/L) after adjustments for covariates. The weighted incidences of AF also did not differ according to the CRP levels. In contrast, persistent elevation of CRP or hsCRP levels (≥1 mg/L at all visits) was associated with a higher risk of AF compared with nonpersistent elevation of CRP or hsCRP levels after adjustment for covariates in both unweighted and weighted cohorts.

CONCLUSION

A high CRP level at a single measurement was not associated with the risk of AF, whereas persistently elevated CRP levels independently predicted the development of AF.

Role of inflammatory signaling in atrial fibrillation

Atrial fibrillation (AF), the most prevalent arrhythmia, is often associated with enhanced inflammatory response. Emerging evidence points to a causal role of inflammatory signaling pathways in the evolution of atrial electrical, calcium handling and structural remodeling, which create the substrate of AF development. In this review, we discuss the clinical evidence supporting the association between inflammatory indices and AF development, the molecular and cellular mechanisms of AF, which appear to involve multiple canonical inflammatory pathways, and the potential of anti-inflammatory therapeutic approaches in AF prevention/treatment.

High mobility group box 1 was associated with thrombosis in patients with atrial fibrillation

INTRODUCTION

High mobility group box 1 (HMGB1) is a member of the HMGB family that is involved in inflammatory disease-related thrombosis. We hypothesize that HMGB1 and its downstream factors are associated with thrombosis in atrial fibrillation (AF).

MATERIALS AND METHODS

Our experimental materials were the left atrial appendage (LAA) tissues from patients undergoing valve replacement. The samples were divided into 3 groups: a sinus rhythm group (n = 15), an AF(+)thrombus(-)group (n = 15), and an AF(+) thrombus (+)group (n = 15). The expression of HMGB1, Toll-like receptor 4 (TLR4), advanced glycation end product (RAGE), myeloid differentiation factor 88 (MyD88), nuclear factor κB (NFκB), p-NFκB, and tissue factor (TF) were detected by Western blot and immunohistochemical (IHC) staining. The expressions of interleukin-1 beta, interleukin 6, and tumor necrosis factor-alpha were detected by quantitative real-time PCR.

RESULTS

The Western blots revealed significantly higher expressions of HMGB1, MyD88, p-NFκB/NFκB, and TF in the AF(+)thrombus(+) group than in the other 2 groups. However, no differences in TLR4 or RAGE expression were found between the groups. IHC staining also revealed higher expressions of HMGB1 and TF in the AF(+)thrombus(+) group. The increased mRNA expressions of classic inflammatory factors (i.e., interleukin-1 beta, interleukin 6, and tumor necrosis factor-alpha) in AF(+)thrombus(+) group further validated the correlation between inflammation and thrombi in atrial fibrillation.

CONCLUSIONS

HMGB1 was associated with thrombosis in patients with AF via the MyD88/NFκB pathway after adjustment for cardiac and extra cardiac inflammation variables.

α-adrenoceptor-mediated enhanced inducibility of atrial fibrillation in a canine system inflammation model

The exact mechanism associated with inflammation and atrial fibrillation (AF) remains unknown. The aim of the present study was to investigate the roles of connexin 43 (Cx43) and a1‑adrenergic receptor (α1‑AR) activation in the pathogenesis of system inflammation‑induced AF. A canine model of chronic low‑grade system inflammation was established by administrating a low dose of lipopolysaccharide (LPS; 0.1 µg/kg) for 2 weeks. Programmed stimulation was applied on the right atrial appendage to determine the effective refractory periods (ERP) and the window of vulnerability (WOV). Tumor necrosis factor α (TNF‑α) and interleukin 6 (IL‑6) levels in plasma and atrial tissue were measured by ELISA. Cx43, Toll‑like receptor 4 (TLR4) and nuclear factor κB (NF‑κB) proteins were analyzed using western blotting or immunohistochemistry. Administration of LPS for 2 weeks increased the concentration of TNF‑α and IL‑6 in the plasma and right atrium. ERP was markedly shortened and cumulative WOV was significantly widened in the LPS group. Following treatment with LPS, the amount of Cx43 protein in the area of intercalated disk increased. In addition, a high‑density of Cx43 in the lateral connection was identified. LPS also induced the activation of NF‑κB in the canine atrium. Administration with the α1‑AR blocker doxazosin prevented the production of LPS‑induced inflammatory cytokine and reversed the enhanced vulnerability to atrial fibrillation. Doxazosin inhibited the LPS‑induced increase in Cx43 protein and heterogeneous distribution, and prevented the activation of NF‑κB. These results indicated that chronic low‑grade system inflammation may increase the inducibility of AF in a canine model. The underlying mechanism may be involved in the LPS‑induced activation of NF‑κB, and the increase in Cx43 expression and lateral distribution via an α1-AR-dependent pathway.