Atrial fibrillation and inflammation

Spirometry in atrial fibrillation: what's the catch?

INTRODUCTION

People with COPD rarely have COPD alone, and the commonest co-morbidities occurring with COPD are cardiovascular. Whilst multiple studies have explored the association between major cardiovascular events and COPD, less attention has been paid to arrhythmias, specifically atrial fibrillation (AF). AF and COPD frequently occur together, posing challenges in diagnosis and management. In this review, we describe the relationship between AF and COPD epidemiologically and physiologically, demonstrating the role of spirometry as a diagnostic and disease management tool.

AREAS COVERED

We provide epidemiological evidence that COPD and AF are independent risk factors for one another, that either disease is highly prevalent amongst people with the other, and that they have shared risk factors; all of which contribute to adverse prognostic. We elucidated common pathophysiological mechanisms implicated in AF-COPD. We ultimately present the epidemiological and physiological evidence with a view to highlight specific areas where we feel spirometry is of value in the management of AF-COPD.

EXPERT OPINION

AF and COPD commonly co-occur, there is often diagnostic delay, increased risk of reduced cardioversion success, and missed opportunity to intervene to reduce stroke risk. Greater awareness and timelier diagnosis and guideline directed management may improve outcomes for people with both diseases.

Systemic immune-inflammation index predicts new-onset atrial fibrillation after ST elevation myocardial infarction

Aim: To investigate the predictive capacity of a systemic immune-inflammation index (SII) in detecting new-onset atrial fibrillation (NOAF) following ST segment elevation myocardial infarction (STEMI). Patients & methods: A total of 402 STEMI patients were enrolled in the study. The patients were divided into two groups according to NOAF development. Results: A cut-off point of 1,228,000 for SII was identified with 60% sensitivity and 78.1% specificity to predict NOAF following STEMI. According to pairwise analysis of receiver operating characteristic curve analysis, the predictive power of SII in detecting NOAF following STEMI was similar to high-sensitive C-reactive protein, and better than neutrophil-to-lymphocyte ratio or platelet-to-lymphocyte ratio. Conclusion: SII can be used as one of the independent predictors of NOAF following STEMI.

Predictive values of C-reactive protein/albumin ratio in new-onset atrial fibrillation after coronary artery bypass grafting

OBJECTIVE

This study aimed to investigate the predictive value of the newly defined C-Reactive Protein (CRP)/Albumin Ratio (CAR) in determining the development of atrial fibrillation (AF) in comparison with other inflammatory markers, such as Neutrophil/Lymphocyte (N/L) Ratio and Platelet/Lymphocyte (P/L) Ratio, in patients undergoing Coronary Artery Bypass Grafting (CABG) surgery.

METHODS

The population of this observational study consisted of 415 patients undergoing CABG. The study cohort was subdivided into two groups based on the development of AF. Complete blood counts, serum CRP, and serum albumin levels were evaluated before the CABG. The CAR, N/L, and P/L ratios of all the patients were calculated. Predictors of postoperative AF were determined by multiple logistic regression analysis (MLRA).

RESULTS

During follow-up, 136 patients (32.8%) developed postoperative AF. With MLRA, independent risk factors for postoperative AF were determined as follows: fasting glucose level (OR: 1.01; 95 % CI: 1.00-1.01, P <0.001), age (OR: 1.12; 95 % CI: 1.07-1.17, P <0.001), left ventricle ejection fraction (OR: 0.90; 95 % CI: 0.87-0.94, P <0.001), male gender (OR: 3.32; 95 % CI: 1.39-7.90, P = 0.007), 24-hour drainage amount (OR: 1.004; 95 % CI: 1.002-1.005, P <0.001), and CAR (OR: 1.82; 95 % CI: 1.53-2.16, P <0.001). Receiver Operating Characteristic curve analysis showed that CAR (C-statistic: 0.75; 95% CI: 0.71-0.79, p< 0.001) was a significant predictor of AF.

CONCLUSION

Novel inflammatory marker CAR can be used as a reliable marker to predict the development of AF following CABG.

Relationship between c-reactive protein/albumin ratio and new-onset atrial fibrillation after coronary artery bypass grafting

OBJECTIVE

This study aimed to investigate the predictive value of the newly defined C-Reactive Protein (CRP)/Albumin Ratio (CAR) in determining the development of atrial fibrillation (AF) in comparison with other inflammatory markers, such as Neutrophil/Lymphocyte (N/L) Ratio and Platelet/Lymphocyte (P/L) Ratio, in patients undergoing Coronary Artery Bypass Grafting (CABG) surgery.

METHODS

The population of this observational study consisted of 415 patients undergoing CABG. The study cohort was subdivided into two groups based on the development of AF. Complete blood counts, serum CRP, and serum albumin levels were evaluated before the CABG. The CAR, N/L, and P/L ratios of all the patients were calculated. Predictors of postoperative AF were determined by multiple logistic regression analysis (MLRA).

RESULTS

During follow-up, 136 patients (32.8%) developed postoperative AF. With MLRA, independent risk factors for postoperative AF were determined as follows: fasting glucose level (OR: 1.01; 95 % CI: 1.00-1.01, P <0.001), age (OR: 1.12; 95 % CI: 1.07-1.17, P <0.001), left ventricle ejection fraction (OR: 0.90; 95 % CI: 0.87-0.94, P <0.001), male gender (OR: 3.32; 95 % CI: 1.39-7.90, P = 0.007), 24-hour drainage amount (OR: 1.004; 95 % CI: 1.002-1.005, P <0.001), and CAR (OR: 1.82; 95 % CI: 1.53-2.16, P <0.001). Receiver Operating Characteristic curve analysis showed that CAR (C-statistic: 0.75; 95% CI: 0.71-0.79, p< 0.001) was a significant predictor of AF.

CONCLUSION

Novel inflammatory marker CAR can be used as a reliable marker to predict the development of AF following CABG.

Incidence of aspirin resistance is higher in patients with acute coronary syndrome and atrial fibrillation than without atrial fibrillation

In patients with atrial fibrillation, standard anticoagulation with a vitamin K antagonist plus dual antiplatelet therapy with a P2Y12 inhibitor and aspirin is the standard of care after percutaneous coronary intervention (PCI). While this therapy reduces the risk of thrombosis and stroke, it increases the risk of bleeding. It is unclear whether the antiplatelet effect of aspirin and clopidogrel may worsen atrial fibrillation (AF). OBJECTIVE Thus we aimed to analyze platelet aspirin resistance (AR) and clopidogrel resistance (CR) in acute coronary (ACS) patients based on sinus rhythm (SR) and AF. METHODS In this prospective trial, we included 543 patients (mean age: 62± 12 years; range: 26 - 89 years) who were on aspirin and clopidogrel therapy after the diagnosis of acute coronary syndrome. AR and CR were analyzed by a Multiplate® MP-0120 device by using the method of whole blood aggregometry. RESULTS AF patients had significantly higher age, mean platelet volume, and High-Sensitivity C-Reactive Protein (p< 0.01 for each parameter). Similarly, Arachidonic-acid induced (ASPI) aggregation was higher in AF patients compared to SR patients (666±218 vs. 187±179, p<0.001). Among the ACS patients, significantly more female patients had AF (p<0.001). The incidence of hypertension in the AF group was higher compared to the SR group (p<0.001). However, adenosine diphosphate levels were not at a significant level in the two groups. CONCLUSION Our findings indicate that the platelet inhibitory effect of Aspirin was worse for patients with AF, suggesting that the effectiveness of aspirin may be less in the prophylaxis of thromboembolism and more a bleeding risk.

The CHA2DS2-VASc score for predicting atrial fibrillation in patients presenting with ST elevation myocardial infarction: prospective observational study

BACKGROUND

Atrial fibrillation (AF) is the most common form of supraventricular arrhythmia following ST-elevation myocardial infarction (STEMI). The CHA2DS2-VASc and CHADS2 scores are used to estimate thromboembolic risk in cases of AF. Their usefulness in predicting the development of AF in patients presenting STEMI is unknown.

OBJECTIVE

To evaluate the predictive value of the CHADS2 and CHA2DS2-VASc scores in patients with AF following STEMI.

DESIGN AND SETTING

This prospective cohort study on 696 patients with STEMI was conducted at a tertiary-level cardiology clinic in a public university hospital.

METHODS

Models including clinical and laboratory parameters were constructed to test the predictive value of CHADS2 and CHA2DS2-VASc scores. Patients were divided into two groups: with and without AF. Predictors of AF were determined using multivariate regression analysis.

RESULTS

In the patients with AF, CHADS2 and CHA2DS2-VASc scores were significantly higher than in those without AF (for both P < 0.001). Factors associated with AF in multivariate analyses included CHA2DS2-VASc score (odds ratio, OR: 1.48; 95% confidence interval, CI: 1.25-1.75; P < 0.001), peak creatine kinase-myocardial binding (OR: 1.002; 95% CI: 1.00-1.003; P = 0.0024), duration of the coronary intensive care unit stay (OR: 1.69; 95% CI: 1.24-12.30; P = 0.001) and no use of renin-angiotensin system blockers (OR: 2.16; 95% CI: 1.14-4.10; P = 0.0017). Receiver operating characteristic curve analyses showed that CHA2DS2-VASc scores were significant predictors for new-onset AF (C-statistic: 0.698; 95% CI: 0.631-0.765; P < 0.001).

CONCLUSION

CHADS2 and CHA2DS2-VASc scores predicted new AF in patients presenting STEMI.

Time Series Gene Expression Profiling and Temporal Regulatory Pathway Analysis of Angiotensin II Induced Atrial Fibrillation in Mice

Background/Aim: Angiotensin II (Ang II) and hypertension play critical roles in the pathogenesis of the atrial remodeling that contributes to atrial fibrillation (AF). However, the gene expression profiles and signaling pathways in atria during the development of AF induced by Ang II remain unknown.

Methods: Wild-type male mice (C57BL/6 background, 10 weeks old) were administered an infusion of Ang II (2000 ng/kg/min) using an osmotic pump for 1, 2, and 3 weeks. Blood pressure (BP) was measured by the tail-cuff method. AF was induced and recorded. Atrial enlargement and remodeling were examined by echocardiography and Masson’s trichrome staining. Time-series microarray analyses were conducted to examine gene expression profiles and pathways.

Results: Ang II infusion resulted in marked elevation of systolic BP, increased AF incidence and duration, atrial enlargement, fibrosis, and atrial infiltration of myofibroblasts and F4/80-positive macrophages in a time-dependent manner. Microarray results showed that 1,719 genes were differentially expressed in the atrium at weeks 1, 2, and 3 after Ang II infusion. Gene ontology showed that these genes participate mainly in immune system processes, and regulation of cell migration, cell adhesion, complement activation, and the inflammatory response. Significant pathways included lysosomal and phagosomal pathways, which are involved in antigen processing and presentation, as well as chemokine signaling, and extracellular matrix–receptor interaction, which are known to play important roles in Ang II-induced AF. Moreover, these differentially expressed genes were classified into 50 profiles by hierarchical cluster analysis. Of these, eight profiles were significant and contained a total of 1,157 genes. Gene co-expression network analysis identified that Pik3cg (also known as phosphoinositide-3-kinase regulatory subunit 3) was localized in the core of the gene network, and was the most highly expressed among the Pik3 isoforms at different time points.

Conclusion: The present findings revealed that many genes are involved in Ang II-induced AF, and highlighted that Pik3cg may play a central role in this disease.

Biomarkers in Atrial Fibrillation and Heart Failure

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice and an important contributor to cardiovascular morbidity and mortality. Although the exact mechanisms behind AF are not completely elucidated, the underlying pathophysiological changes have been well described. Predisposal factors for AF include the older age, the increased left atrial size, the decreased left atrial function, the presence of heart failure and left ventricular systolic dysfunction and the presence of coronary heart disease or pulmonary or mitral valve disease. In addition to these factors, emerging evidence demonstrate that myocardial strain, fibrosis and inflammation, are associated with AF as well as the pathogenesis of the arrhythmia. The natruretic peptide system including Atrial Natriuretic Peptide (ANP), Brain Natriuretic Peptide (BNP) and C-type Natriuretic Peptide (CNP) is indicative of the level of myocardial strain which may predispose to AF. As a result, the aforementioned peptides are increased in AF patients. The levels of myocardial fibrosis biomarkers, such as ST2 and Galectin-3, are elevated suggesting atrial structural abnormalities, while the increased levels of CRP and Interleukin-6 supplement the inflammatory profile of AF patients. Emerging data for the aforementioned biomarkers are discussed in the present review.

Immunoproteasome Subunit β5i Promotes Ang II (Angiotensin II)–Induced Atrial Fibrillation by Targeting ATRAP (Ang II Type I Receptor–Associated Protein) Degradation in Mice

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia and increases the risk of stroke, heart failure, and death. Ang II (angiotensin II) triggers AF, mainly through stimulation of the AT1R (Ang II type I receptor). The immunoproteasome is a highly efficient proteolytic machine derived from the constitutive proteasome, but the role it plays in regulating AT1R activation and triggering AF remains unknown. Here, we show that among the catalytic subunits, β5i (PSMB8) expression, and chymotrypsin-like activity were the most significantly upregulated in atrial tissue of Ang II–infused mice or serum from patients with AF. β5i KO (β5i knockout) in mice markedly attenuated Ang II-induced AF incidence, atrial fibrosis, inflammatory response, and oxidative stress compared with WT (wild type) animals, but injection with recombinant adeno-associated virus serotype 9–β5i increased these effects. Moreover, we found that ATRAP (AT1R-associated protein) was a target of β5i. Overexpression of ATRAP significantly attenuated Ang II-induced atrial remodeling and AF in recombinant adeno-associated virus serotype 9–β5i-injected mice. Mechanistically, Ang II upregulated β5i expression to promote ATRAP degradation, which resulted in activation of AT1R-mediated NF-κB signaling, increased NADPH oxidase activity, increased TGF (transforming growth factor)-β1/Smad signaling, and altered the expression of Kir2.1 and CX43 (connexin 43) in the atria, thereby affecting atrial remodeling and AF. In summary, this study identifies β5i as a negative regulator of ATRAP stability that contributes to AT1R activation and to AF, highlighting that targeting β5i activity may represent a potential therapeutic approach for the treatment of hypertensive AF.

Looking into a conceptual framework of ROS-miRNA-atrial fibrillation

Atrial fibrillation (AF) has been recognized as a major cause of cardiovascular-related morbidity and mortality. MicroRNAs (miRNAs) represent recent additions to the collection of biomolecules involved in arrhythmogenesis. Reactive oxygen species (ROS) have been independently linked to both AF and miRNA regulation. However, no attempts have been made to investigate the possibility of a framework composed of ROS–miRNA–AF that is related to arrhythmia development. Therefore, this review was designed as an attempt to offer a new approach to understanding AF pathogenesis. The aim of this review was to find and to summarize possible connections that exist among AF, miRNAs and ROS to understand the interactions among the molecular entities underlying arrhythmia development in the hopes of finding unappreciated mechanisms of AF. These findings may lead us to innovative therapies for AF, which can be a life-threatening heart condition. A systemic literature review indicated that miRNAs associated with AF might be regulated by ROS, suggesting the possibility that miRNAs translate cellular stressors, such as ROS, into AF pathogenesis. Further studies with a more appropriate experimental design to either prove or disprove the existence of an ROS–miRNA–AF framework are strongly encouraged.

Impact of intensive glycemic control on the incidence of atrial fibrillation and associated cardiovascular outcomes in patients with type 2 diabetes mellitus (from the Action to Control Cardiovascular Risk in Diabetes Study)

Atrial fibrillation (AF) is prevalent in patients with type 2 diabetes mellitus (DM) and is associated with markers of poor glycemic control; however, the impact of glycemic control on incident AF and outcomes is unknown. The aims of this study were to prospectively evaluate if intensive glycemic control in patients with DM affects incident AF and to evaluate morbidity and mortality in patients with DM and incident AF. A total of 10,082 patients with DM from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) cohort were studied in a randomized, double-blind fashion. Participants were randomized to an intensive therapeutic strategy targeting a glycated hemoglobin level of <6.0% or a standard strategy targeting a glycated hemoglobin level of 7.0% to 7.9%. Incident AF occurred in 159 patients (1.58%) over the follow-up period, at a rate of 5.9 per 1,000 patient-years in the intensive-therapy group and a rate of 6.37 per 1,000 patient-years in the standard-therapy group (p = 0.52). In a multivariate model, predictors of incident AF were age, weight, diastolic blood pressure, heart rate, and heart failure history. Patients with DM and new-onset AF had a hazard ratio of 2.65 for all-cause mortality (95% confidence interval 1.8 to 3.86, p <0.0001), a hazard ratio of 2.1 for myocardial infarction (95% confidence interval 1.33 to 3.31, p = 0.0015), and a hazard ratio of 3.80 for the development of heart failure (95% confidence interval 2.48 to 5.84, p <0.0001). In conclusion, intensive glycemic control did not affect the rate of new-onset AF. Patients with DM and incident AF had an increased risk for morbidity and mortality compared with those without AF.

Relationship between brain natriuretic peptides and recurrence of atrial fibrillation after successful direct current cardioversion: a meta-analysis

BACKGROUND

Atrial fibrillation (AF) recurrence is common after successful direct current cardioversion (DCCV), with a 40% rate of recurrence within the first month. Several studies have investigated the potential association between brain natriuretic peptide (BNP) or N-terminal (NT)-proBNP levels before DCCV and the risk of AF recurrence, but results have been inconsistent. We, therefore, conducted a systematic review and meta-analysis of all available data to determine whether sinus rhythm (SR) maintenance after successful DCCV may be determined by preprocedural BNP and NT-proBNP levels.

METHODS

We systematically searched Scopus, the Cochrane library, EMBASE, and MEDLINE databases to identify publications evaluating BNP or NT-proBNP levels in relation to post-DCCV AF recurrence, indexed from inception to September 2013. Among the initial 1,067 citations, 18 studies fulfilled the specified criteria. The difference in BNP and NT-proBNP concentrations in the AF recurrence and the SR-maintaining group was estimated by the standardized mean difference and the estimates of the pooled outcomes were evaluated using random-effects models.

RESULTS

Baseline BNP levels in the AF recurrence group were significantly higher compared to BNP levels in the SR-maintaining group (standardized mean difference [SMD] -1.51, confidence interval [CI] [-2.53, -0.48], P = 0.004). Similar results were observed for NT-proBNP levels, which were significantly higher in the AF recurrence group compared with the SR-maintaining group (SMD -0.63, CI [-1.13, -0.14], P = 0.01).

CONCLUSIONS

Our analysis suggests that low preprocedural BNP/NT-proBNP levels are associated with SR maintenance. The use of BNP or NT-proBNP for prediction of long-term response to DCCV appears to be useful and should be further evaluated.

Airflow obstruction, lung function, and incidence of atrial fibrillation: the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

Reduced low forced expiratory volume in 1 second (FEV1) is reportedly associated with an increased risk of atrial fibrillation (AF). Extant reports do not provide separate estimates for never smokers or for blacks, who incongruously have lower AF incidence than whites.

METHODS AND RESULTS

We examined 15 004 middle-aged blacks and whites enrolled in the Atherosclerosis Risk in Communities (ARIC) cohort study. Standardized spirometry data were collected at the baseline examination. Incident AF was identified from the first among the following: International Classification of Diseases codes for AF on hospital discharge records or death certificates or 12-lead ECGs performed during 3 triennial follow-up visits. Over an average follow-up of 17.5 years, a total of 1691 participants (11%) developed new-onset AF. The rate of incident AF was inversely associated with FEV1 in each of the 4 race and sex groups. After multivariable adjustment for traditional cardiovascular disease risk factors and height, hazard ratios of AF comparing the lowest with the highest quartile of FEV1 were 1.37 (95% confidence interval, 1.02-1.83) for white women, 1.49 (95% confidence interval, 1.16-1.91) for white men, 1.63 (95% confidence interval, 1.00-2.66) for black women, and 2.36 (95% confidence interval, 1.30-4.29) for black men. The above associations were observed across all smoking status categories. Moderate/severe airflow obstruction (FEV1/forced vital capacity <0.70 and FEV1 < 80% of predicted value) was also associated with higher AF incidence.

CONCLUSIONS

In this large population-based study with a long-term follow-up, reduced FEV1 and obstructive respiratory disease were associated with a higher AF incidence after adjustment for measured confounders.

Natriuretic Peptides as Predictors of Atrial Fibrillation Recurrences Following Electrical Cardioversion

Electrical cardioversion (ECV) can be effective in restoring sinus rhythm (SR) in the majority of patients with atrial fibrillation (AF). Several factors that predispose to AF recurrences, such as age, AF duration and left atrial size have been used to guide a decision for cardioversion, but increasing evidence suggests that they may be rather poor markers of left atrial structural remodeling that determines the long-term success of a rhythm control strategy. In this context, the use of easily obtainable biomarkers, such as the levels of atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP), to predict AF recurrences may be preferable. Since ANP production is associated with the extent of functional atrial myocardium, and both ANP and BNP reflect atrial pressure and mechanical stretching, these peptides are good candidate biomarkers to assess predisposition to AF recurrences. In this review we focus on the pathophysiological mechanisms and the available clinical evidence regarding the prediction of AF recurrences following successful ECV from pre-procedural ANP and BNP levels.

TLR2 was overexpressed independent of IL-6 in patients with valvular atrial fibrillation

Toll-like receptor 2 (TLR2) has recently been shown to be up-regulated in patients with non-valvular atrial fibrillation (AF). The present study was aimed to determine whether the pathogenesis and development of AF is associated with the up-regulation of TLR2. Clinical data and right atrial appendage (RAA) specimens were collected from 20 patients with persisten AF (PeAF), 15 patients with paroxysmal AF (PaAF) and 13 patients with no history of AF undergoing valvular replacement. The results showed that gene expression and protein content of TLR2 were increased in both the AF subgroups, compared with the sinus rhythm (SR) group. Between the two AF subgroups, PaAF had a higher TLR2 level than PeAF. However, no difference in interluekin (IL)-6 content was found among the three groups, and no correlation was found between TLR2 and IL-6 in PeAF patients (r = 0.090, P = 0.706), PaAF patients (r = 0.408, P = 0.131) and AF patients (r = -0.301, P = 0.079). Immunohistochemical analysis revealed that TLR2 was distributed in RAAs of AF patients and confirmed the immunoblotting results. In conclusion, we demonstrated that TLR2 was elevated in AF (especially PaAF) patients with valvular heart disease, further implicating inflammation involved in the pathogenesis and development of AF.

Serum γ-glutamyltransferase activity in patients with nonvalvular atrial fibrillation

Procoagulant and prothrombotic states in patients with chronic atrial fibrillation (AF) are higher than those in patients with normal sinus rhythm. We assessed and compared serum γ-glutamyltranferase (GGT) activity in elderly patients with nonvalvular AF and control participants with normal sinus rhythm. Consecutive patients (n = 81) with nonvalvular chronic AF and 210 age- and gender-matched control participants with normal sinus rhythm were retrospectively included in the study from the outpatient cardiology clinic. Presence of coronary artery disease, hypertension, gender, hyperlipidemia, diabetes mellitus, smoking status, glucose, total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and ejection fraction were comparable between the 2 groups (P > .05 for all). However, serum γ-GGT activity was significantly higher (P = .003) in patients with AF compared with those without AF. We have shown that serum γ-GGT activity is independently associated with chronic nonvalvular AF.