Role of tissue C-reactive protein in atrial cardiomyocytes of patients undergoing catheter ablation of atrial fibrillation: pathogenetic implications

Association of Estimated Glomerular Filtration Rate (eGFR) and High-Sensitivity C-Reactive Protein (Hs-CRP) with the Risk of New-Onset Atrial Fibrillation in Patients with Diabetes

Background

Both renal function decline and systemic inflammation may synergistically increase the risk of atrial fibrillation (AF). This study investigates the association between estimated glomerular filtration rate (eGFR) and high-sensitivity C-reactive protein (hs-CRP) levels with the risk of new-onset AF in patients with diabetes mellitus.

Methods

We included diabetic patients without AF who participated in physical exams in the Kailuan Study from 2006 to 2010. Participants were categorized into four groups based on baseline eGFR and hs-CRP levels: 1) high eGFR (≥60 mL/min/1.73m²) and low hs-CRP (<3 mg/L) (n=6,915), 2) high eGFR and high hs-CRP (≥3 mg/L) (n=3,154), 3) low eGFR (<60 mL/min/1.73m²) and low hs-CRP (n=4,638), 4) low eGFR and high hs-CRP (n=1,809). We employed multivariable Cox regression analysis to evaluate the relationships between eGFR, hs-CRP, and new-onset AF, adjusting for confounders including smoking status, alcohol consumption, blood pressure, fasting blood glucose (FBG), heart rate, lipid levels, body mass index (BMI), and medication usage. Competing risk analysis was also performed.

Results

Among 16,516 patients, 222 developed new-onset AF over a mean follow-up of 12.6 years. After adjusting for confounders, elevated hs-CRP and reduced eGFR were significantly associated with higher risk of new-onset AF compared to the high eGFR/low hs-CRP group. These findings remained consistent after excluding AF cases within the first 2-year. No significant interaction between eGFR and hs-CRP was observed (P=0.227). Subgroup analysis revealed that the combination of eGFR and hs-CRP had predictive value primarily in males under 60 years of age, individuals with FBG <9 mmol/L, hypertension, and those not on hypoglycemic medications.

Conclusion

In diabetic patients, decreased eGFR and elevated hs-CRP were independently linked to an increased risk of new-onset AF, emphasizing the importance of monitoring these factors for early detection and prevention of AF.

Oxidized high-density lipoprotein associates with atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common heart arrhythmia and considered to be a progressive chronic disease associated with increased morbidity and mortality. Recent data suggest a link between inflammation, oxidative stress, and AF, although the underlying mechanisms are not fully understood. Because oxidized lipoproteins cause structural damage and electrophysiologic changes in cardiomyocytes, it is feasible that the transformation of atheroprotective high-density lipoprotein (HDL) into dysfunctional HDL contributes to the development of AF.

OBJECTIVE

The purpose of this study was to determine whether a reduced antioxidant function of HDL is associated with the presence of AF.

METHODS

In this multicenter cross-sectional cohort study, we assessed HDL function in sera of 1206 participants. Patients were divided into groups according to the presence of AF (n = 233) or no AF (n = 973). A validated cell-free biochemical assay was used to determine reduced HDL antioxidant function as assessed by increased normalized HDL lipid peroxide content (nHDLox).

RESULTS

Participants with AF had a 9% higher mean relative nHDLox compared to persons without AF (P = .025). nHDLox was strongly associated with AF in all models of logistic regression, including the analysis adjusted for age, sex, and risk factors for AF (all P ≤.01).

CONCLUSION

Reduced antioxidant HDL function is associated with the presence of AF, which supports growing evidence that impaired lipoprotein function is linked to electrophysiological changes in cardiomyocytes. nHDLox is one of several contributors to the initiation and perpetuation of AF.

The Role of Biochemical Cardiac Markers in Atrial Fibrillation

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia. Proteins are a component of cardiac biomarkers containing cell structures that are released into the circulation when a myocardial injury occurs. They are essential in the diagnosis, risk assessment, and treatment of patients who have chest pain, are thought to have acute coronary syndrome, or are experiencing acute heart failure exacerbations. There are numerous biochemical cardiac markers, but this article summarizes the basic role of major biochemical cardiac markers, including cardiac natriuretic peptides, cardiac troponins, C-reactive protein (CRP), creatine kinase-MB, heart-type fatty acid-binding protein, ischemia-modified albumin, lipoprotein (a), osteopontin (OPN), and soluble suppression of tumorigenicity 2 (sST2), in AF. Atrial natriuretic peptide may serve as an indicator of atrial integrity, which may help to select appropriate treatment approaches for AF. Higher levels of N-terminal pro-B-type natriuretic peptide and brain natriuretic peptide are predictive of incidental AF. Increased troponin T release may indicate better clinical results following AF ablation. Similarly, CRP increases the risk of the AF-increasing calcium (Ca) influx in atrial myocytes, but not because of atrial fibrosis. Patients with postoperative AF have lower FABP3 gene expression in the atrium. Lipoprotein (a) (Lp[a]) may play a causative role in the onset of AF and impact various cardiac tissues. Clinical trials for Lp(a)-lowering drugs should assess their impact on preventing AF. Also, OPN was highly expressed in the circulation of AF patients and further increased with the progression of AF. sST2 was a reliable predictor of new-onset AF and can improve the accuracy of the AF risk model. There is a greater chance that these cardiac biomarkers might be employed to enhance clinical risk stratification in AF.

Effects of Inflammatory Cell Death Caused by Catheter Ablation on Atrial Fibrillation

Atrial fibrillation (AF) poses a serious healthcare burden on society due to its high morbidity and the resulting serious complications such as thrombosis and heart failure. The principle of catheter ablation is to achieve electrical isolation by linear destruction of cardiac tissue, which makes AF a curable disease. Currently, catheter ablation does not have a high long-term success rate. The current academic consensus is that inflammation and fibrosis are central mechanisms in the progression of AF. However, artificially caused inflammatory cell death by catheter ablation may have a significant impact on structural and electrical remodeling, which may affect the long-term prognosis. This review first focused on the inflammatory response induced by apoptosis, necrosis, necroptosis, pyroptosis, ferroptosis and their interaction with arrhythmia. Then, we compared the differences in cell death induced by radiofrequency ablation, cryoballoon ablation and pulsed-field ablation. Finally, we discussed the structural and electrical remodeling caused by inflammation and the association between inflammation and the recurrence of AF after catheter ablation. Collectively, pulsed-field ablation will be a revolutionary innovation with faster, safer, better tissue selectivity and less inflammatory response induced by apoptosis-dominated cell death.

Role of interatrial conduction in atrial fibrillation. Mechanistic insights from renewal theory-based fibrillatory dynamic analysis

Background

Interatrial conduction has been postulated to play an important role in atrial fibrillation (AF). The pathways involved in interatrial conduction during AF remain incompletely defined.

Objective

We recently showed physiological assessment of fibrillatory dynamics could be performed using renewal theory, which determines rates of phase singularity formation (λ_f) and destruction (λ_d). Using the renewal approach, we aimed to understand the role of the interatrial septum and other electrically coupled regions during AF.

Method

RENEWAL-AF is a prospective multicenter observational study recruiting AF ablation patients (ACTRN 12619001172190). We studied unipolar electrograms obtained from 16 biatrial locations prior to ablation using a 16-electrode Advisor HD Grid catheter. Renewal rate constants λ_f and λ_d were calculated, and the relationships between these rate constants in regions of interatrial connectivity were examined.

Results

Forty-one AF patients (28.5% female) were recruited. A positive linear correlation was observed between λ_f and λ_d (1) across the interatrial septum (λ_f r² = 0.5, P < .001, λ_d r² = 0.45, P < .001), (2) in regions connected by the Bachmann bundle (right atrial appendage–left atrial appendage λ_f r² = 0.29, P = .001; λ_d r² = 0.2, P = .008), and (3) across the inferior interatrial routes (cavotricuspid isthmus–left atrial septum λ_f r² = 0.67, P < .001; λ_d r² = 0.55, P < .001). Persistent AF status and left atrial volume were found to be important effect modifiers of the degree of interatrial renewal rate statistical correlation.

Conclusion

Our findings support the role of interseptal statistically determined electrical disrelation in sustaining AF. Additionally, renewal theory identified preferential conduction through specific interatrial pathways during fibrillation. These findings may be of importance in identifying clinically significant targets for ablation in AF patients.

Role of Inflammation in the Pathogenesis of Atrial Fibrillation

Atrial fibrillation (AF) is one of the most common arrhythmias encountered in clinical practice. AF is a major risk factor for stroke, which is associated with high mortality and great disability and causes a significant burden on society. With the development of catheter ablation, AF has become a treatable disease, but its therapeutic outcome has been limited so far. In persistent and long-standing AF, the expanded AF substrate is difficult to treat only by ablation, and a better understanding of the mechanism of AF substrate formation will lead to the development of a new therapeutic strategy for AF. Inflammation is known to play an important role in the substrate formation of AF. Inflammation causes and accelerates the electrical and structural remodeling of the atria via pro-inflammatory cytokines and other inflammatory molecules, and enhances the AF substrate, leading to the maintenance of AF and further inflammation, which forms a vicious spiral, so-called "AF begets AF". Breaking this vicious cycle is expected to be a key therapeutic intervention in AF. In this review, we will discuss the relationship between AF and inflammation, the inflammatory molecules included in the AF-related inflammatory process, and finally the potential of those molecules as a therapeutic target.

Canine atrial fibrillation: Pathophysiology, epidemiology and classification

Atrial fibrillation (AF) is the most common non-physiological arrhythmia in dogs and humans. Its high prevalence in both species and the impact it has on survival time and quality of life of affected patients, makes it a very relevant topic of medical research. Significant developments in understanding the mechanisms underlying this arrhythmia in humans has occurred over the last decades and some of this knowledge is being applied to veterinary medicine, despite the many differences between species. This article reviews the current understanding of the pathophysiology of AF. The epidemiology and classification of AF in dogs will also be discussed.

Atrial septum biopsy for direct substrate characterization in atrial fibrillation

INTRODUCTION

The aim of this study was to describe and illustrate the technique of performing interatrial septum biopsy and to demonstrate its use for direct histological substrate characterization in atrial fibrillation (AF).

METHODS AND RESULTS

Biopsies were performed in four patients who underwent AF catheter ablation. Bipal 7 bioptome was directed through a steerable sheath directly onto the septum. Fluoroscopic views as well as echocardiography-guided techniques were utilized to confirm that the tip was oriented towards the interatrial septum. The bioptome was then placed on the right atrial (RA) septum and maneuvered to obtain the specimens (at least 1 mm in size) from the posterior septal region of the RA, adjacent to the fossa ovalis. Bioptome placement and sample acquisition were successful in all patients at the first attempt. No patient developed any minor or major complications during the procedure and hospital stay. All the biopsy specimens had proper qualities for histological assessments and revealed a variety of pathologies including fibrosis, inflammation, and fatty infiltration.

CONCLUSION

Atrial septum biopsies could be safely performed guided by fluoroscopy and transesophageal echocardiography. The obtained specimens allowed for a detailed localized substrate characterization which is of great interest in AF.

Biomarkers of Atrial Fibrillation in Metabolic Syndrome

Whether the increased atrial fibrillation (AF) risk in metabolic syndrome (MetS) patients is due to the syndrome as a whole or simply the sum of the risks of its individual component parts is still obscure. These two clinical entities share many pathophysiological links and thus distinction between a casual observation and a significant association is difficult. Biomarkers associated with pathogenesis of AF in the context of MetS have the ability to refine future risk prediction. In the present review we identify circulating substances that could be regarded as potential biomarkers for prediction of incident AF, or of cardiovascular events in the setting of AF in patients with MetS. Cardiac myocyte injury and stress markers (troponin and natriuretic peptides), markers of renal function (glomeral filtration rate, cystatin-C), and inflammation markers/mediators (interleukin- 6, CRP) are promising biomarkers of patients with AF and MetS.

Reduction of atrial fibrillation burden by pulmonary vein isolation leads to a decrease of CD11b expression on inflammatory cells

Aims

It is hypothesized that inflammation could promote structural and electrical remodelling processes in atrial fibrillation (AF). Atrial infiltration of monocytes and granulocytes has been shown to be dependent on CD11b expression. The aim of this study was to investigate whether treatment of AF by pulmonary vein isolation (PVI) may lead to reduced inflammation, as indicated by a decrease of CD11b expression on monocytes and granulocytes.

Methods and results

Flow-cytometric quantification analysis and determination of systemic inflammatory markers of peripheral blood were performed in 75 patients undergoing PVI 1 day before and 6 months after PVI. The extent of activation of monocytes and granulocytes was measured by quantifying the cell adhesion molecule CD11b. The mean expression of CD11b on monocytes (20.9 ± 2.5 vs. 10.2 ± 1.4; P < 0.001) and granulocytes (13.9 ± 1.6 vs. 6.8 ± 0.5; P < 0.001), as well as the relative count of CD11b-positive monocytes (P < 0.05) and CD11b-positive granulocytes (P < 0.01) were significantly reduced when comparing the identical patients before and 6 months after PVI. Systemic inflammatory parameters showed only a declining tendency after 6 months. Patients with unsuccessful PVI and ongoing AF on the day of follow-up showed no decrease in CD11b expression.

Conclusions

A significant reduction of CD11b expression on monocytes and granulocytes, as a sign of reduced cellular inflammation, was achieved by treatment of AF using PVI. These data strongly support that AF is not only a consequence of but also a cause for inflammatory processes, which, in turn, may contribute to atrial remodelling.

Pathophysiology of cancer therapy-provoked atrial fibrillation

Atrial fibrillation (AF) occurs with increased frequency in cancer patients, especially in patients who undergo surgery or chemotherapy. AF disturbs the prognosis of cancer patients and challenges therapeutic outcomes of cancer treatment. Elucidating the mechanisms of cancer-induced AF would help identify specific strategies for preventing AF occurrence. In addition to concurrent risk factors of cancer and AF, cancer surgery, side effects of anticancer agents, and cancer-associated immune responses play critical roles in the genesis of AF. In this review, we provide succinct potential mechanisms of AF genesis in cancer patients.

Inflammation and C-reactive protein in atrial fibrillation: cause or effect?

Atrial fibrillation is associated with substantial morbidity and mortality rates. The incompletely understood pathogenesis of this cardiac dysrhythmia makes it difficult to improve approaches to primary and secondary prevention. Evidence has accumulated in regard to a relationship between inflammation and atrial fibrillation. Investigators have correlated the dysrhythmia with myocarditis, pericardiotomy, and C-reactive protein levels, suggesting that inflammation causes atrial fibrillation or participates in its onset and continuation. Conversely, other investigators suggest that atrial fibrillation induces an inflammatory response. In this review, we summarize and critically discuss the nature and clinical role of inflammation and C-reactive protein in atrial fibrillation.

A variant of IL6R is associated with the recurrence of atrial fibrillation after catheter ablation in a Chinese Han population

Background

Recent studies have identified a variant, rs4845625, in the interleukin-6 receptor (IL6R) gene associated with Atrial Fibrillation (AF). Levels of circulating interleukin-6 and other proinflammatory molecules have consistently been associated with a risk for AF and its recurrence after catheter ablation. This study tested the hypothesis that variant rs4845625 is associated with AF recurrence after catheter ablation in a Chinese Han population.

Methods

A total of 278 consecutive patients (mean age 59.4±11.5 years, 43% female) with paroxysmal (36.0%), persistent (59.7%), and permanent (4.3%) AF who underwent catheterablation from 2007–2011, were included in this study. Patients were monitored for 12 months for a recurrence of AF. The SNP rs4845625 was genotyped using high resolution melting analysis.

Results

In our study cohort, an early recurrence of AF (ERAF), defined as a recurrence within the first 4 weeks, was observed in 42.8% of the patients, whereas late recurrence of AF (LRAF) (between 3 and 12 months) occurred in 25.9% of the patients. No significant differences in baseline clinical or echocardiographic characteristics were observed between patients with ERAF and LRAF. In contrast, the presence of the T allele of rs4845625 was associated with an increase in the risk for both ERAF (odds ratio [OR]: 1.84, 95% confidence interval [CI]: 1.31–2.59, p = 4.10×10⁻⁴) and LRAF (OR: 1.92, 95% CI: 1.30–2.81, p = 0.001). Furthermore, this association was significant after adjustments for age, sex, hypertension, diabetes and other risk factors. No significant relationship between rs4845625 and serum levels of IL6 was observed.

Conclusions

In this study, a variant of the IL6R gene, rs4845625, was found confer risk to AF recurrence after catheter ablation in a Chinese Han population. Our findings indicated that the IL6R pathway or inflammation may play important rols in the recurrence of AF after catheter ablation.

Association between C-reactive protein and atrial fibrillation recurrence after catheter ablation: a meta-analysis

BACKGROUND

Atrial fibrillation (AF) is associated with inflammation. Increased serum C-reactive protein (CRP) levels are important representatives of an inflammatory state of AF. A variety of studies have evaluated whether increased CRP levels have an association with AF recurrence after catheter ablation. However, the results remain inconsistent, therefore, this meta-analysis was conducted to offer suggestions.

HYPOTHESIS

Increased baseline CRP have an association with AF recurrence after catheter ablation.

METHODS

Electronic databases including PubMed, Embase, Medline, ISI Web of Knowledge, and ScienceDirect were searched until December 31, 2012 for any CRP-associated studies. Overall and subgroup analyses were performed. Standardized mean difference (SMD) and 95% confidence interval (CI) were used to evaluate the associations between CRP levels and postablation AF recurrence. Statistical analysis was performed with Review Manager 5.2 and Stata 11.0.

RESULTS

Seven available studies were identified, which included 526 patients (179 recurrence vs 347 no recurrence). Overall, increased baseline CRP levels had significant positive association with postablation AF recurrence. The SMD in the CRP levels was 0.65 units (95% CI: 0.30-0.99), and the z-score for overall effect was 3.70 (P = 0.0002). The heterogeneity test showed that there were moderate differences between individual studies (P = 0.006, I(2) = 67%). Metaregression revealed that different sample sizes of studies possibly accounted for the heterogeneity. Positive associations were also found in subgroup analyses based on sample size. When stratifying for ethnicity, similarly significant associations were found in both European (Caucasian) and Asian populations.

CONCLUSIONS

Investigations demonstrate that baseline CRP levels are greater in patients with postablation AF recurrence. Further studies with larger sample size and delicate design for CRP should be conducted.

Response of high-sensitive C-reactive protein to catheter ablation of atrial fibrillation and its relation with rhythm outcome

Aims

This study investigated the possible association between hs-CRP as well as hs-CRP changes and rhythm outcome after AF catheter ablation.

Methods

We studied 68 consecutive patients with AF undergoing catheter ablation. hs-CRP levels were measured using commercially available assays before and 6 months after catheter ablation. Serial 7-day Holter ECGs were used to detect AF recurrences.

Results

Early AF recurrence (ERAF, within one week) was observed in 38%, while late AF recurrence (LRAF, between 3 and 6 months) occurred in 18% of the patients. None of the baseline clinical or echocardiographic variables was predictive of ERAF or LRAF. Baseline hs-CRP measured 2.07±1.1 µg/ml and was not associated with ERAF and LRAF. At 6 months, hs-CRP levels were comparable with baseline values (2.14±1.19 µg/ml, p = 0.409) and were also not related with LRAF. However, patients with LRAF showed an hs-CRP increase from 2.03±0.61 to 2.62±1.52 µg/ml (p = 0.028). Patients with an hs-CRP change in the upper tertile (>0.2 µg/ml) had LRAF in 32% as opposed to 11% (p = 0.042) in patients in the lower (<−0.3 µg/ml) or intermediate (−0.3–0.2 µg/ml) tertile.

Conclusions

Changes in hs-CRP but not baseline hs-CRP are associated with rhythm outcome after AF catheter ablation. This finding points to a link between an inflammatory response and AF recurrence in this setting.