The relevance of the association between inflammation and atrial fibrillation

Genetically predicted systemic inflammation and the risk of atrial fibrillation: A bidirectional two-sample Mendelian randomization study

Background

Systemic inflammation has been proposed to be associated with the incidence of atrial fibrillation (AF), but whether it is a cause or a consequence of AF remains uncertain. We sought to explore the causal associations between systemic inflammation and AF using bidirectional Mendelian randomization (MR) analysis.

Methods

Independent genetic variants strongly associated with AF were selected as instrumental variables from the largest genome-wide association study (GWAS) with up to 1,030,836 individuals. Regarding inflammation traits, genetic associations with 41 inflammatory cytokines and 5 inflammatory biomarkers were obtained from their corresponding GWASs databases. Effect estimates were primarily evaluated using the inverse-variance weighted (IVW) method, supplemented by sensitivity analyses using MR-Egger, weighted median, and MR-PRESSO methods.

Results

In our initial MR analyses, we observed suggestive associations of genetically predicted interleukin-17 (IL-17), interleukin-2 receptor subunit alpha (IL-2rα), and procalcitonin (PCT) with AF. One standard deviation (SD) increase in IL-17, IL-2rα, and PCT caused an increase in AF risk by 6.3 % (OR 1.063, 95 %CI 1.011---1.118, p = 0.018), 4.9 % (OR 1.049, 95 %CI 1.007---1.094, p = 0.023) and 3.4 % (OR 1.034, 95 %CI 1.005---1.064, p = 0.022), respectively. Furthermore, our reverse MR analyses indicated that genetically predicted AF contributed to a suggestive increase in the levels of macrophage inflammatory protein-1β (MIP1β) (β 0.055, 95 %CI 0.006 to 0.103, p = 0.028), while a decrease in the levels of fibrinogen (Fbg) (β -0.091, 95 %CI -0.140 to -0.041, p < 0.001), which remained significant after multiple test correction.

Conclusions

Our MR study identified several inflammatory biomarkers with suggestive causal associations regarding the upstream and downstream regulation of AF occurrence, offering new insights for therapeutic exploitation of AF. Further research is required to validate the underlying link between systemic inflammation and AF in larger cohorts.

The Role of Major Inflammatory Biomarkers in the Pathogenesis of Atrial Fibrillation

Many studies have reported a relationship between inflammation and atrial fibrillation (AF). According to the literature, inflammation is the key component in pathophysiological processes during the development of AF; the amplification of inflammatory pathways triggers AF, and, at the same time, AF increases the inflammatory state. The plasma levels of several inflammatory biomarkers are elevated in patients with AF; therefore, inflammation might contribute to both the maintenance and occurrence of AF and its thromboembolic complications. Numerous inflammatory markers have been linked to AF, including CD40 ligand, fibrinogen, matrix metalloproteinase (MMP)-9, monocyte chemoattractant protein-1, myeloperoxidase, plasminogen activator inhibitor-1, and serum amyloid A. There are many pathophysiological aspects of AF that are linked to these inflammatory biomarkers, including atrial structural remodeling and atrial dilatation, increased atrial myocyte expression, fluctuations in calcium cycling, cardiac remodeling promotion, increased cardiac myocyte proliferation and terminal differentiation, production of several MMPs, the pathogenesis of atherosclerosis and cardiomyocyte apoptosis, an increased degree of fibrosis in atrial myocardium, and the progression and development of atherogenesis and atherothrombosis. The present review article aims to provide an updated overview and focus on the basic role of different biomarkers of inflammation in the pathophysiological aspects of the pathogenesis of AF.

Put out the fire: The pleiotropic anti-inflammatory action of non-vitamin K oral anticoagulants

Non-vitamin K antagonist oral anticoagulants (NOACs) should be the preferred anticoagulant strategy for preventing ischemic stroke in patients with atrial fibrillation (AF) at increased thromboembolic risk and for treating deep venous thromboembolism (DVT) in the general population. Beyond their inhibiting action on the activated factor X (FXa) or thrombin (FIIa), NOACs showed some pleiotropic anti-inflammatory effects. The present review aimed to describe the role of FXa and FIIa in the inflammation pathway and the potential anti-inflammatory effects of NOACs.

The Impact of Intermittent Hypoxemia on Left Atrial Remodeling in Patients with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) is a significant risk factor for left atrial (LA) remodeling. Intermittent hypoxemia occurs during the sleep cycle in patients with OSAS and plays a crucial role in cardiovascular pathologies such as stroke, arrhythmia, and coronary artery disease. However, there is very little information about the role of intermittent hypoxemia in LA remodeling in patients with OSAS. In total, 154 patients with sleep-related breathing disorders (SRBD) were prospectively recruited for this study. All enrolled SRBD patients underwent polysomnography and echocardiography. Significant OSAS was defined as an oxygen desaturation index (ODI) of ≥10 per hour. Intermittent hypoxia/reoxygenation (IHR) stimulation was used to test the effect of hypoxia on the viability, reactive oxygen species, apoptosis, and inflammation-associated cytokine expression in the HL-1 cell line. To investigate the effect of patients’ exosomes on HIF-1 and inflammation-associated cytokine expression, as well as the relationship between ODI and their expression, exosomes were purified from the plasma of 95 patients with SRBD and incubated in HL-1 cells. The LA size was larger in patients with significant OSAS than in those without. There was a significant association between ODI, lowest SpO2, mean SpO2, and LA size (all p < 0.05) but not between the apnea–hypopnea index and LA size. IHR condition caused increased LDH activity, reactive oxygen species (ROS) levels, and apoptosis in HL-1 cells and decreased cellular viability (all p < 0.05). The expression of HIF-1α, TNF-α, IL-6, and TGF-β increased in the IHR condition compared with the control (all p < 0.05). The expression of HIF-1α, IL-1β, and IL-6 increased in the HL-1 cells incubated with exosomes from those patients with significant OSAS than those without (all p < 0.05). There was a significantly positive correlation between ODI and the expression of HIF-1α, TNF-α, IL-1β, IL-6, and TGF-β; a significantly negative correlation between mean SpO2 and IL-6 and TGF-β; and a significantly negative correlation between the lowest SpO2 and HIF-1α (all p < 0.05). In conclusion, intermittent hypoxemia was strongly associated with LA remodeling, which might be through increased ROS levels, LDH activity, apoptosis, and the expression of HIF-1α and inflammation-associated cytokines.

Macrophage Inflammatory Protein-1 Alpha, a Potential Biomarker for Predicting Left Atrial Remodeling in Patients With Atrial Fibrillation

Objectives: Left atrial (LA) remodeling itself is an independent risk factor for ischemic stroke and mortality, with or without atrial fibrillation (AF). Macrophage inflammatory protein-1 alpha (MIP-1α) has been reported to be involved in the induction of autoimmune myocarditis and dilated cardiomyopathy. Little is known about whether MIP-1α can be used to predict LA remodeling, especially in patients with AF.

Methods: We prospectively enrolled 78 patients who had received a cardiac implantable electronic device due to sick sinus syndrome in order to define AF accurately. AF was diagnosed clinically before enrollment, according to 12-lead electrocardiography (ECG) and 24-h Holter test in 54 (69%) patients. The serum cytokine levels and the mRNA expression levels of peripheral blood leukocytes were checked and echocardiographic study was performed on the same day within 1 week after the patients were enrolled into the study. The 12-lead ECG and 24-h Holter test were performed on the same day of the patients' enrollment, and the device interrogation was performed every 3 months after enrollment. The enrolled patients were clinically followed up for 1 year.

Results: There was no difference in baseline characteristics, cytokine levels and mRNA expression between patients with and without AF. Larger LA volume was positively correlated with higher levels of MIP-1α (r = 0.461, p ≤ 0.001) and the atrial high-rate episodes (AHREs) burden (r = 0.593, p < 0.001), and negatively correlated with higher levels of transforming growth factor (TGF)-β1 (r = −0.271, p = 0.047) and TGF-β3 (r = −0.279, p = 0.041). The higher AHREs burden and MIP-1α level could predict LA volume independently. The mRNA expression of RORC was negatively associated with the MIP-1α level.

Conclusions: This study showed that higher MIP-1α was significantly associated with LA remodeling and may have the potentials to predict LA remodeling in terms of a larger LA volume, and that circadian gene derangement might affect the expression of MIP-1α.

New Strategies for the Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in the clinical practice. It significantly contributes to the morbidity and mortality of the elderly population. Over the past 25-30 years intense effort in basic research has advanced the understanding of the relationship between the pathophysiology of AF and atrial remodelling. Nowadays it is clear that the various forms of atrial remodelling (electrical, contractile and structural) play crucial role in initiating and maintaining the persistent and permanent types of AF. Unlike in ventricular fibrillation, in AF rapid ectopic firing originating from pulmonary veins and re-entry mechanism may induce and maintain (due to atrial remodelling) this complex cardiac arrhythmia. The present review presents and discusses in detail the latest knowledge on the role of remodelling in AF. Special attention is paid to novel concepts and pharmacological targets presumably relevant to the drug treatment of atrial fibrillation.

Association between the Genetic Polymorphisms of CCL2, CCL5, CCL8, CCR2, and CCR5 with Chronic Hepatitis C Virus Infection in the Chinese Han Population

Background: Hepatitis C virus (HCV) infection is a global public health burden. Chronic HCV infection leads to the development of fibrosis, cirrhosis, liver cancer, and liver failure over time.Methods: A total of 250 patients with chronic HCV infection and 299 healthy blood donors were recruited. Sixteen candidate single nucleotide polymorphisms (SNPs) in chemokine (C-C motif) ligand 2 (CCL2), CCL5, CCL8, C-C chemokine receptor 2 (CCR2), and CCR5 were genotyped in all participants.Results: The rs1024610 AA genotype was significantly associated with decreased susceptibility to chronic HCV infection. Aspartate aminotransferase (AST) levels, AST/platelet ratio index, and the fibrosis 4 score were significantly lower in the CCL2 rs1024610 T allele and haplotype ATGC carriers. Moreover, expression levels of collagen IV (C-IV) and laminin (LN) were significantly higher in patients with the CCL5 rs2280788 C allele compared to the non-carriers. Similarly, the expression levels of C-IV, LN, and hyaluronic acid were significantly higher in patients with the CCL5 haplotype, TGCT. No significant differences were identified between the SNPs/haplotypes and plasma levels of CCL2, CCL5, CCL8, CCR2, and CCR5 in the healthy controls, and the rs1024610 allele alteration had no effect on CCL2 promoter activity.Conclusions: This is the first study to report an association between CCL2 rs1024610 and the risk of chronic HCV infection in the Chinese Han population. rs1024610 and ATGC haplotype in CCL2 were reasonable candidate markers of liver abnormalities. rs2280788 and TGCT haplotype in CCL5 are likely to play a significant role in liver fibrosis during chronic HCV infection.

The association of novel inflammatory marker GlycA and incident atrial fibrillation in the Multi-Ethnic Study of Atherosclerosis (MESA)

Background

Emerging evidence has implicated that inflammation contributes to the pathogenesis of atrial fibrillation (AF). GlycA is a novel marker of systemic inflammation with low intra-individual variability and high analytic precision. GlycA has been associated with incident cardiovascular disease (CVD) independent of other inflammatory markers. However, whether GlycA is associated with AF, specifically, has yet to be established. We examined the association between GlycA and AF in a multi-ethnic cohort.

Methods

We studied 6,602 MESA participants aged 45–85, with no clinical CVD at baseline, with data on GlycA and incident AF. We used multivariable-adjusted Cox models to evaluate the association between GlycA and incident AF. We also examined other inflammatory markers [high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL6) and fibrinogen] and incident AF for comparison.

Results

The mean (SD) age was 62 (10) years, 53% women. The mean plasma GlycA was 381 (62) μmol/L. Over median follow-up of 12.9 years, 869 participants experienced AF. There was no statistically significant association between GlycA and incident AF after adjusting for sociodemographics, CVD risk factors, and other inflammatory markers [Hazard Ratio (95% CI) per 1 SD increment in GlycA: 0.97 (0.88–1.06)]. Neither hsCRP nor fibrinogen was associated with incident AF in same model. In contrast, IL-6 was independently associated with incident AF [HR 1.12 per 1 SD increment (1.05–1.19)].

Conclusions

Although GlycA has been associated with other CVD types, we found that GlycA was not associated with AF. More research will be required to understand why IL-6 was associated with AF but not GlycA.

Clinical trial registration

MESA is not a clinical trial. However, the cohort is registered at: URL: https://clinicaltrials.gov/ct2/show/NCT00005487 Unique identifier: NCT00005487.

Atrial fibrillation type modulates the clinical predictive value of neutrophil-to-lymphocyte ratio for atrial fibrillation recurrence after catheter ablation

BACKGROUND

The neutrophil-to-lymphocyte ratio (NLR) has been proposed as an indicator of a systemic inflammatory response. There are baseline differences in the inflammation status between paroxysmal atrial fibrillation (PAF) and persistent AF (PerAF). The NLR changes and late recurrences of AF (LRAF) after ablation depending on the AF type remain unknown.

METHODS

Consecutive AF patients undergoing pulmonary vein isolation (PVI) by radiofrequency catheter ablation were enrolled from September 2014 to June 2018. The peripheral blood leukocyte NLR 1 day before and 36-48 h after PVI were measured. First, the relationship between NLR changes after to before ablation (ΔNLR) and ERAFs/LRAFs in PAF and PerAF patients were investigated to exclude the baseline inflammation status and evaluate catheter ablation induced inflammation. Second, the clinical impact of the NLR for predicting LRAFs was evaluated.

RESULTS

There hundred sixty-nine PAF and 264 PerAF patients from Osaka Rosai AF registry were enrolled. The ratio of ERAFs/LRAFs in PAF and PerAF patients were 26.8%/22.5% and 39.4%/29.9%, respectively. In PAF and PerAF patients, the ΔNLR was significantly higher with ERAF than no-ERAF (p = 0.022 and p = 0.010, respectively). In PAF patients, the ΔNLR was significantly higher with LRAF than no-LRAF (p = 0.017), while with PerAF, the ΔNLR did not significantly differ between LRAFs and no-LRAFs. In PAF, the ΔNLR was independently and significantly associated with LRAFs after PVI (p = 0.029).

CONCLUSION

The ΔNLR was significantly higher only in PAF patients with LRAFs than no-LRAFs, but not in PerAF patients. The ΔNLR was useful for predicting LRAFs after PVI in PAF patients.

Inflammatory and Infectious Processes Serve as Links between Atrial Fibrillation and Alzheimer's Disease

Atrial fibrillation (AF) is one of the most prevalent forms of arrhythmia that carries an increased risk of stroke which, in turn, is strongly associated with cognitive decline. The majority of dementia cases are caused by Alzheimer's disease (AD) with obscure pathogenesis. While the exact mechanisms are unknown, the role of inflammatory processes and infectious agents have recently been implicated in both AD and AF, suggesting a common link between these maladies. Here, we present the main shared pathways underlying arrhythmia and memory loss. The overlapping predictive biomarkers and emerging joint pharmacological approaches are also discussed.

Effects of Rivaroxaban on Biomarkers of Coagulation and Inflammation: A Post Hoc Analysis of the X-VeRT Trial

Introduction  This X-VeRT (eXplore the efficacy and safety of once-daily oral riVaroxaban for the prevention of caRdiovascular events in patients with nonvalvular aTrial fibrillation scheduled for cardioversion) substudy evaluated the effects of treatment with rivaroxaban or a vitamin-K antagonist (VKA) on levels of biomarkers of coagulation (D-dimer, thrombin–antithrombin III complex [TAT] and prothrombin fragment [F1.2]) and inflammation (high sensitivity C-reactive protein [hs-CRP] and high-sensitivity interleukin-6 [hs-IL-6]) in patients with atrial fibrillation (AF) who were scheduled for cardioversion and had not received adequate anticoagulation at baseline (defined as, in the 21 days before randomization: no oral anticoagulant; international normalized ratio <2.0 with VKA treatment; or <80% compliance with non-VKA oral anticoagulant treatment).

Methods  Samples for biomarker analysis were taken at baseline ( n  = 958) and treatment completion (42 days after cardioversion; n  = 918). The influence of clinical characteristics on baseline biomarker levels and the effect of treatment on changes in biomarker levels were evaluated using linear and logistic models.

Results  Baseline levels of some biomarkers were significantly associated with type of AF (D-dimer and hs-IL-6) and with history of congestive heart failure (hs-CRP, D-dimer, and hs-IL-6). Rivaroxaban and VKA treatments were associated with reductions from baseline in levels of D-dimer (−32.3 and −37.6%, respectively), TAT (−28.0 and −23.1%, respectively), hs-CRP (−12.5 and −17.9%, respectively), and hs-IL-6 (−9.2 and −9.8%, respectively). F1.2 levels were reduced from baseline in patients receiving a VKA (−53.0%) but not in those receiving rivaroxaban (2.7%).

Conclusion  Anticoagulation with rivaroxaban reduced levels of key inflammation and coagulation biomarkers to a similar extent as VKAs, with the exception of F1.2. Further investigation to confirm the value of these biomarkers in patients with AF is merited.

The role of fish oil in attenuating cardiac oxidative stress, inflammation and fibrosis in rat model of thyrotoxicosis

Hyperthyroidism is associated with cardiovascular complications. Fish oil reduces risk of cardiovascular diseases. This study aims to evaluate the impact of fish oil on myocardial oxidative stress, inflammation and fibrosis in rat model of thyrotoxicosis. Rats were randomized into four groups; control rats, fish oil treated rats (FO, 100mg omega-3/100g body weight/day), hyperthyroid rats (Hyper, i.p levothyroxine 3 mg/kg/day), and hyperthyroid rats treated with fish oil (Hyper + FO) for 8 weeks. Changes in oxidants/antioxidants, inflammatory and fibrotic markers were measured. Thyrotoxicosis increased serum endothelin-1, thiobarbituric acid reactive substances (TBARS) and reduced activities of cardiac catalase and super oxide dismutase (SOD). Cardiac fibrosis paralleled with a decrease of matrix metalloproteinase -2 (MMP2) levels were observed in Hyper group. Use of FO increased activities of SOD and catalase, increased TBARS levels, and attenuated cardiac fibrosis by normalizing MMP-2 levels. Use of FO may attenuate cardiac oxidative stress and fibrosis in hyperthyroid states.

Diffuse Gallium-67 Accumulation in the Left Atrial Wall Detected Using SPECT/CT Fusion Images

Gallium-67 scintigraphy is useful for detecting active inflammation. We show a 66-year-old female patient with atrial fibrillation and diffuse thickening of the left atrial wall due to acute myocarditis, who presented diffuse abnormal accumulation of gallium-67 in the left atrium on single photon emission computed tomography/computed tomography (SPECT/CT) fusion images. In the second gallium-67 scan 2 months after the first scintigraphy, the abnormal accumulation in the heart was no longer visible. Gallium-67 SPECT/CT images helped understanding the disease condition that temporary inflammation in the left atrium caused atrial fibrillation.

Do preoperative C-reactive protein and mean platelet volume levels predict development of postoperative atrial fibrillation in patients undergoing isolated coronary artery bypass grafting?

Introduction

Atrial fibrillation (AF) after coronary artery bypass grafting (CABG) operation is associated with increased risk of prolonged hospitalisation, health expenses and adverse clinical outcomes.

Aim

To investigate the relationship of atrial fibrillation after an isolated coronary artery bypass operation with levels of mean platelet volume and C-reactive protein.

Material and methods

Among 1240 patients who underwent operations for isolated coronary artery bypass grafting with cardiopulmonary bypass between January 2007 and May 2014, 1138 (91.8%) patients with preoperative normal sinusal rhythm were enrolled in the study. Patients were assigned to group 1 (n = 294) comprising patients who developed atrial fibrillation in the first 72 postoperative hours or group 2 (n = 844) comprising patients who remained in normal sinusal rhythm in the postoperative period.

Results

The incidence of postoperative atrial fibrillation was 25.8%. The preoperative mean platelet volume (fl) and C-reactive protein (mg/dl) values in group 1 were 9.1 ±0.5 and 1.1 ±0.9 respectively, while these values were 8.3 ±0.6 and 0.5 ±0.3 respectively in group 2, which was statistically significant (p = 0.0001). Length of stay in the hospital (p = 0.0001) was higher in group 1. The values of mean platelet volume (fl) and mean C-reactive protein (mg/dl) were 9.9 ±0.9 and 30.9 ±3.4 respectively in group 1, while the values of mean platelet volume (fl) and mean C-reactive protein (mg/dl) were 8.8 ±0.6 and 24.9 ±4.8 respectively in group 2 (p = 0.0001 for mean platelet volume, p = 0.0001 for C-reactive protein). The difference between the groups was statistically significant in terms of postoperative neurologic events (p = 0.0001) and hospital mortality (p = 0.001). Increased C-reactive protein and mean platelet volume levels were found to be independent predictors of postoperative atrial fibrillation.

Conclusions

In our study, elevated preoperative mean platelet volume and C-reactive protein levels were associated with development of postoperative atrial fibrillation.

Chemokines and Heart Disease: A Network Connecting Cardiovascular Biology to Immune and Autonomic Nervous Systems

Among the chemokines discovered to date, nineteen are presently considered to be relevant in heart disease and are involved in all stages of cardiovascular response to injury. Chemokines are interesting as biomarkers to predict risk of cardiovascular events in apparently healthy people and as possible therapeutic targets. Moreover, they could have a role as mediators of crosstalk between immune and cardiovascular system, since they seem to act as a “working-network” in deep linkage with the autonomic nervous system. In this paper we will describe the single chemokines more involved in heart diseases; then we will present a comprehensive perspective of them as a complex network connecting the cardiovascular system to both the immune and the autonomic nervous systems. Finally, some recent evidences indicating chemokines as a possible new tool to predict cardiovascular risk will be described.

Mendelian randomization studies: a review of the approaches used and the quality of reporting

BACKGROUND

Mendelian randomization (MR) studies investigate the effect of genetic variation in levels of an exposure on an outcome, thereby using genetic variation as an instrumental variable (IV). We provide a meta-epidemiological overview of the methodological approaches used in MR studies, and evaluate the discussion of MR assumptions and reporting of statistical methods.

METHODS

We searched PubMed, Medline, Embase and Web of Science for MR studies up to December 2013. We assessed (i) the MR approach used; (ii) whether the plausibility of MR assumptions was discussed; and (iii) whether the statistical methods used were reported adequately.

RESULTS

Of 99 studies using data from one study population, 32 used genetic information as a proxy for the exposure without further estimation, 44 performed a formal IV analysis, 7 compared the observed with the expected genotype-outcome association, and 1 used both the latter two approaches. The 80 studies using data from multiple study populations used many different approaches to combine the data; 52 of these studies used some form of IV analysis; 44% of studies discussed the plausibility of all three MR assumptions in their study. Statistical methods used for IV analysis were insufficiently described in 14% of studies.

CONCLUSIONS

Most MR studies either use the genotype as a proxy for exposure without further estimation or perform an IV analysis. The discussion of underlying assumptions and reporting of statistical methods for IV analysis are frequently insufficient. Studies using data from multiple study populations are further complicated by the combination of data or estimates. We provide a checklist for the reporting of MR studies.

Association between rs2200733 and rs7193343 genetic variants and atrial fibrillation in a Spanish population, and meta-analysis of previous studies

INTRODUCTION AND OBJECTIVES

The objectives of this study were to analyze the association between two genetic variants (rs2200733 and rs7193343) in a Spanish population and the risk of developing atrial fibrillation, and to carry out a systematic review and meta-analysis of these associations.

METHODS

We performed a case-control study involving 257 case patients with atrial fibrillation and 379 controls. The case patients were individuals who had donated samples to the Spanish National DNA Bank; the controls were participating in a population-based cross-sectional study. Genotyping was carried out using a TaqMan assay. We conducted a systematic literature search in which 2 independent reviewers extracted the necessary information. The study involved a meta-analysis, a heterogeneity analysis, and a meta-regression analysis to identify the variables that explain the heterogeneity across studies.

RESULTS

In our population, the presence of atrial fibrillation was found to be associated with rs2200733 (odds ratio = 1.87; 95% confidence interval, 1.30-2.70), but not with rs7193343 (odds ratio = 1.18; 95% confidence interval, 0.80-1.73). In the meta-analysis, we observed an association between atrial fibrillation and both variants: odds ratio = 1.71 (95% confidence interval, 1.54-1.90) for rs2200733 and odds ratio = 1.18 (95% confidence interval, 1.11-1.25) for rs7193343. We observed heterogeneity among the studies dealing with the association between rs2200733 and atrial fibrillation, partially related to the study design, and the strength of association was greater in case-control studies (odds ratio = 1.83) than in cohort studies (odds ratio = 1.41).

CONCLUSIONS

Variants rs2200733 and rs7193343 are associated with a higher risk of atrial fibrillation. Case-control studies tend to overestimate the strength of association between these genetic variants and atrial fibrillation.

Atrial fibrillation: inflammation in disguise?

Atrial fibrillation is highly prevalent, and affected patients are at an increased risk of a number of complications, including heart failure and thrombo-embolism. Over the past years, there has been increasing interest in the role of inflammatory processes in atrial fibrillation, from the first occurrence of the arrhythmia to dreaded complications such as strokes or peripheral emboli. As the standard drug combination which aims at rate control and anticoagulation only offers partial protection against complications, newer agents are needed to optimize treatment. In this paper, we review recent knowledge regarding the impact of inflammation on the occurrence, recurrence, perpetuation and complications of the arrhythmia, as well as the role of anti-inflammatory therapies in the treatment for the disease.