Is atrial fibrillation an inflammatory disorder?

Atrial fibrillation: a review of recent studies with a focus on those from the duke clinical research institute

Atrial fibrillation is the most common arrhythmia and accounts for one-third of hospitalizations for rhythm disorders in the United States. The prevalence of atrial fibrillation averages 1% and increases with age. With the aging of the population, the number of patients with atrial fibrillation is expected to increase 150% by 2050, with more than 50% of atrial fibrillation patients being over the age of 80. This increasing burden of atrial fibrillation will lead to a higher incidence of stroke, as patients with atrial fibrillation have a five- to sevenfold greater risk of stroke than the general population. Strokes secondary to atrial fibrillation have a worse prognosis than in patients without atrial fibrillation. Vitamin K antagonists (e.g., warfarin), direct thrombin inhibitors (dabigatran), and factor Xa inhibitors (rivaroxaban and apixaban) are all oral anticoagulants that have been FDA approved for the prevention of stroke in atrial fibrillation. This review will summarize the experience of anticoagulants in patients with atrial fibrillation with a focus on the experience at the Duke Clinic Research Institute.

Structural and Functional Remodeling of the Left Atrium: Clinical and Therapeutic Implications for Atrial Fibrillation

Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice. Despite advances in our understanding of the pathophysiology of this complex arrhythmia, current therapeutic options remain suboptimal. This review aimed to delineate the atrial structural and functional remodeling leading to the perpetuation of AF. We explored the complex changes seen in the atria in various substrates for AF and the therapeutic options available to prevent these changes or for reverse remodeling. Here we also highlighted the emerging role of aggressive risk factor management aimed at the arrhythmogenic atrial substrate to prevent or retard AF progression.

Uric acid increases the incidence of ventricular arrhythmia in patients with left ventricular hypertrophy

BACKGROUNDS

Elevated uric acid (UA) level is reported to be related to the development of left ventricular hypertrophy (LVH) which is associated with high incidence of ventricular tachycardia (VT) and sudden cardiac death. However, little is known about the association between serum UA levels and the occurrence of VT. Thus, we examined the relationship between serum UA levels and the appearance of VT in patients with LVH.

METHODS

The study subjects consisted of 167 patients (110 males, mean age 67.4 ± 12.7 years) with LVH detected by echocardiography. These patients were divided into two groups based on whether VT was presented (defined by more than 5 beats, n = 27) or not (n = 140) by 24-hour Holter ECG monitoring. Left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVDd), the E/A ratio and deceleration time of transmitral flow velocity were assessed by echocardiography in each group. In addition, blood urea nitrogen (BUN), creatinine, estimated glomerular filtration rate (eGFR), sodium, potassium, hemoglobin, total bilirubin and UA were compared in each group.

RESULTS

Echocardiographic findings did not show the difference between the two groups. However, BUN and UA levels in the VT group were significantly higher than those in the Non-VT group (p < 0.01). eGFR was significantly lower in the VT group than that in the Non-VT group (p < 0.01). A multivariate logistic regression analysis identified the UA level as an independent predictive factor for the occurrence of VT (odds ratio 1.61, 95% confidence interval 1.1-2.2, p < 0.01).

CONCLUSIONS

These results suggest that serum UA level is a useful marker for predicting ventricular arrhythmias in patients with LVH.

High-sensitivity troponin T as a biomarker for the development of atrial fibrillation after cardiac surgery

OBJECTIVES

Atrial fibrillation (AF) occurs in ∼ 30% of patients undergoing coronary artery bypass grafting (CABG) and in 40% of patients after valve surgery. High-sensitivity cardiac troponin T (hsTnT) is a specific and high-sensitivity marker of myocardial injury, while N-terminal proB-type natriuretic peptide (NT-proBNP) is an established biomarker for wall remodelling. We investigated whether hsTnT and NT-proBNP levels could be used as valuable biomarkers for AF occurrence after cardiac surgery.

METHODS

We included consecutive haemodynamically stable patients undergoing programmed cardiac surgery with cardiopulmonary bypass pump. We determined hsTnT and NT-proBNP levels before and after cardiac surgery and recorded AF development by prolonged electrocardiogram monitoring.

RESULTS

We included 100 patients with predominantly aortic valve (n = 42) or ischaemic heart (n = 58) diseases. Twenty-nine patients (29%) developed post-surgical AF. Patients developing AF had a longer hospital stay (P = 0.005). hsTnT levels increased after surgery [P < 0.001], indicating perioperative myocardial injury, with higher presurgery levels in patients who developed AF [P = 0.015]. Body mass index and EuroSCORE risk scale were independently associated with higher hsTnT levels presurgery. On univariate analysis, age (P = 0.048), male sex (P = 0.031), indexed left atrial volume (P = 0.042), β-blockers treatment (P = 0.024), type of surgery (valve surgery vs CABG; P = 0.034), EuroSCORE risk scale (P = 0.025) and higher preoperative hsTnT levels (P = 0.009) were predictors of AF development, but NT-proBNP did not reach statistical significance (P = 0.060). hsTnT levels in blood samples obtained the day after surgery were not associated with post-surgical AF development (P = 0.165). In a multivariate model, only higher hsTnT levels before cardiac surgery (>11.87 ng/l) [Odds Ratio, OR; (95% Confidence interval, CI) 4.27 (1.43-12.77), P = 0.009] and male sex [OR 5.10 (1.72-15.13), P = 0.003)] were independently associated with the occurrence of post-surgical AF.

CONCLUSION

High presurgical hsTnT levels were independently predictive of patients developing AF after cardiac surgery. hsTnT levels determined post-surgery suggest that cardiac perioperative myocardial injury is not associated with postoperative AF development. NT-proBNP did not reach statistical significance as a biomarker for AF prediction.

Integrated approach to treatment-resistant atrial fibrillation: additional value of acupuncture

A 62-year-old patient with chronic bronchitis had treatment-resistant atrial fibrillation. Electrical cardioversion was performed, but sinus rhythm (SR) lasted only for some minutes. Administration of amiodarone was withheld in favour of a course of acupuncture treatment in order to increase the success rate of a second attempt of electrical cardioversion. After two acupuncture treatments, spontaneous conversion to SR occurred. Relapses into atrial fibrillation in the following five winters, associated with attacks of bronchitis, also responded to acupuncture. The mechanisms of action of the acupuncture treatment and the value of this integrated approach to treatment are discussed.

What is the significance of perioperative release of macrophage migration inhibitory factor in cardiac surgery?

Cardiac surgery is associated with release of the pleiotropic cytokine macrophage migration inhibitory factor (MIF). The trigger for MIF release has not yet been elucidated. Owing to its intrinsic antioxidative activity, MIF might reduce oxidative stress and protect from myocardial ischemia and reperfusion (I/R) injury. In the present study, patients scheduled for elective cardiac surgery (n=46) were randomized to undergo coronary artery bypass grafting either conventionally with cardiopulmonary bypass and cardioplegic arrest-induced I/R (cCABG) or in an off-pump procedure (OPCAB) with minimized I/R. We report that only patients who underwent cCABG exhibited a postoperative increase of MIF (p=0.024), while both groups showed an increase in interleukin-6. MIF release appears to be primarily mediated by I/R and to a lesser extent by inflammation. Endogenous peroxidase activity (p=0.021) and serum levels of thioredoxin (p=0.003) were significantly higher in patients who underwent cCABG after surgery. Interestingly, perioperative MIF release was associated with an enhanced antioxidant capacity and a significantly reduced postoperative incidence of atrial fibrillation (p=0.018) and acute kidney injury (p=0.048). The present study highlights the role of MIF increase during cardiac surgery in response to oxidative stress. Based on current observations, we hypothesize that intraoperative MIF secretion is due to I/R and enhances the antioxidant capacity in patients during cardiac surgery.

The association between hyperuricemia, left atrial size and new-onset atrial fibrillation

BACKGROUND

Although hyperuricemia was associated with several cardiovascular diseases, the role of uric acid (UA) in left atrial (LA) remodeling and new-onset atrial fibrillation (AF) has not been fully explored. The goal of the present study is to investigate the relationship between UA, LA diameter and the development of AF in the large-scale cohort.

METHODS

The study consisted of 2 parts. First, we investigated the association between serum UA and LA diameter in a single-center database (n = 3043). Second, we studied and compared the risk of new-onset AF among patients with and without hyperuricemia in the nationwide longitudinal cohort in Taiwan (n = 122,524).

RESULTS

Elevated serum level of UA was associated with an increased systemic inflammation, and insulin resistance. The LA diameter was significantly correlated with serum UA (r = 0.341, p value < 0.001). The linear correlation between LA dimension and UA level remained significant after the adjustment for clinical, biochemical and echocardiographic variables. In the nationwide cohort, there were 2339 patients (1.9% of the study population) developing AF during the follow-up of 6.3 ± 3.0 years. The AF occurrence rate was higher in patients with hyperuricemia than those without it (2.1% versus 1.7%; p value < 0.001). Hyperuricemia was a significant risk factor of new-onset AF with a hazard ratio of 1.191 (95% confidence interval = 1.098-1.292, p value < 0.001) in the multivariate Cox regression analysis.

CONCLUSIONS

Hyperuricemia was associated with a larger LA size and may be a novel risk factor for the development of AF.

Improved neurocognitive functions correlate with reduced inflammatory burden in atrial fibrillation patients treated with intensive cholesterol lowering therapy

Background

Atrial fibrillation (AF) is associated with increased mortality and morbidity, including risk for cerebral macro- and microinfarctions and cognitive decline, even in the presence of adequate oral anticoagulation. AF is strongly related to increased inflammatory activity whereby anti-inflammatory agents can reduce the risk of new or recurrent AF. However, it is not known whether anti-inflammatory therapy can also modify the deterioration of neurocognitive function in older patients with AF. In the present study, older patients with AF were treated with intensive lipid-lowering therapy with atorvastatin 40 mg and ezetimibe 10 mg, or placebo. We examined the relationship between neurocognitive functions and inflammatory burden.

Findings

Analysis of inflammatory markers revealed significant reductions in high sensitivity C-reactive protein (hs-CRP), fibroblast growth factor (FGF), granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 receptor antagonist (IL-1RA), interleukin (IL)-9, IL-13 and IL-17, and interferon-γ (IFNγ) in the treatment group compared to placebo. Reduction in plasma concentration of IL-1RA, IL-2, IL-9 and IL-12, and macrophage inflammatory protein-1β (MIP-1β) correlated significantly with improvement in the neurocognitive functions memory and speed. Loss of volume in amygdala and hippocampus, as determined by magnetic resonance imaging (MRI), was reduced in the treatment arm, statistically significant for left amygdala.

Conclusions

Anti-inflammatory therapy through intensive lipid-lowering treatment with atorvastatin 40 mg and ezetimibe 10 mg can modify the deterioration of neurocognitive function, and the loss of volume in certain cerebral areas in older patients with AF.

Trial registration Clinical Trials.gov

NCT00449410

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.

Angiotensin II blockade, YKL-40 and maintenance of sinus rhythm after electrical cardioversion for atrial fibrillation

High levels of the novel inflammatory marker YKL-40 have been demonstrated in inflammatory environments and in remodeling of the extracellular matrix. Both are key components in atrial wall remodeling in atrial fibrillation (AF). We studied the relation between rhythm outcome after electrical cardioversion (ECV) for persistent AF and serum levels of YKL-40. A secondary point of interest was a potential effect of the angiotensin receptor blocker candesartan on YKL-40 levels. In the Candesartan in the Prevention of Relapsing Atrial Fibrillation (CAPRAF) study, 171 patients with persistent AF were randomized to receive candesartan 8mg once daily or placebo for 3-6 weeks before ECV and candesartan 16mg once daily or placebo for 6 months after ECV. Serum levels of YKL-40 were measured in fasting blood samples collected at baseline and at end of the study. Mean age was 64±11 years, and 39 (22.8%) were women. Sinus rhythm was maintained for 6 months after ECV in 41 (23.9%). Baseline levels of YKL-40 were significantly correlated to age (Spearmans rho; rs=0.442; p<0.001), CHA2DS2-VASc(1) score (rs=0.256; p<0.001) and left atrial diameter (rs=0.185; p=0.017). By use of Kaplan-Meier quartile analysis of baseline YKL-40 levels, no relation between YKL-40 levels and risk of AF recurrence was found. End of study YKL-40 levels were unchanged from baseline, both in patients with AF recurrence and those maintaining sinus rhythm for 6 months. Treatment with candesartan had no influence on serum YKL-40 levels.

Effect of renal sympathetic denervation on atrial substrate remodeling in ambulatory canines with prolonged atrial pacing

We have previously demonstrated that catheter-based renal sympathetic denervation (RSD) could suppress atrial fibrillation (AF) in canines with short-time rapid right atrial pacing (RAP). However, the role of renal denervation on atrial remodeling is unclear. The aim of the present study was to explore the long-term effect of RSD on the atrial remodeling during prolonged RAP. Twenty mongrel dogs were implanted with a high-frequency cardiac pacemaker with a transvenous lead inserted into the right atrial appendage. The dogs were divided into three groups: a sham-operated group (n = 6), the chronic RAP (CRAP) group (n = 7), and the CRAP+RSD group (n = 7). In the CRAP+RSD group, a pacemaker was implanted 6 weeks after RSD was performed bilaterally for recovery. RAP was maintained for 5 weeks in CRAP group and CRAP+RSD group. The plasma levels of Angiotensin II and aldosterone were significantly increased in CRAP group compared with sham-operated group, but the increasing trend was inhibited in CRAP+RSD group compared with CRAP group (P<0.05). Similarly, RSD suppressed the increasing trend that prolonged RAP produced in the left atrial levels of ANP, TNF-α and IL-6. Compared with the sham-operated group, the CRAP group had significantly increased levels of caspase-3, bax and Cx40 whereas the level of Bcl-2 decreased (P<0.05). RSD markedly reduced the upregulation of caspase-3, bax and Cx40 and the downregulation of Bcl-2 expression compared with the CRAP group (P<0.05). Picric acid–sirius red staining study suggested that RSD could markedly alleviate the lesion degree of cardic fibrosis induced by CRAP (P<0.05). Immunohistochemistry results showed that the densities of TH- and GAP43- positive nerves were significantly elevated in the CRAP group compared with the sham-operated group, while RSD operation signicantly inhibited the these changes produced by CRAP. These findings suggest that renal denervation could suppress the atrial remodeling after prolonged RAP in ambulatory canines.

Oxidative stress in atrial fibrillation: an emerging role of NADPH oxidase

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Patients with AF have up to seven-fold higher risk of suffering from ischemic stroke. Better understanding of etiologies of AF and its thromboembolic complications are required for improved patient care, as current anti-arrhythmic therapies have limited efficacy and off target effects. Accumulating evidence has implicated a potential role of oxidative stress in the pathogenesis of AF. Excessive production of reactive oxygen species (ROS) is likely involved in the structural and electrical remodeling of the heart, contributing to fibrosis and thrombosis. In particular, NADPH oxidase (NOX) has emerged as a potential enzymatic source for ROS production in AF based on growing evidence from clinical and animal studies. Indeed, NOX can be activated by known upstream triggers of AF such as angiotensin II and atrial stretch. In addition, treatments such as statins, antioxidants, ACEI or AT1RB have been shown to prevent post-operative AF; among which ACEI/AT1RB and statins can attenuate NOX activity. On the other hand, detailed molecular mechanisms by which specific NOX isoform(s) are involved in the pathogenesis of AF and the extent to which activation of NOX plays a causal role in AF development remains to be determined. The current review discusses causes and consequences of oxidative stress in AF with a special focus on the emerging role of NOX pathways.

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.

A review of the current status of pericardial closure following cardiac surgery

Some cardiac surgeons prefer to close the pericardium whenever possible following surgery, others specifically avoid this practice, and still others believe that neither alternative has any meaningful influence on clinical outcomes. Unfortunately, scientific evidence supporting either approach is scarce, making a consensus regarding best practice impossible. In this article, the known functions of the native intact pericardium are summarized, and the arguments for and against pericardial closure after surgery are examined. In addition, the techniques and materials that have been utilized for pericardial closure previously, as well as those that are currently being developed, are assessed.

The relevance of the association between inflammation and atrial fibrillation

BACKGROUND

The relevance of the association between inflammation and atrial fibrillation (AF) is not firmly established. The clinical importance is considerable because inflammation is usually not targeted as a treatment option, minimizing a probable benefit.

MATERIALS AND METHODS

We have used a case-control study with a Mendelian randomization rationale to assess whether proposed risk factors that have a genetic component and are readily detected in circulating blood are causally related to AF. The studied variables were C-reactive protein (CRP) and a representative of the chemokine system, the monocyte chemoattractant protein-1 (CCL2).

RESULTS

Plasma CRP and CCL2 concentrations were significantly higher in AF patients than in the unaffected population. However, when segregated between paroxysmal and permanent, the difference for CRP was only observed in patients with a permanent condition. Plasma CCL2 was raised in both subgroups. Confounding factors were carefully considered, and multivariable analyses revealed that circulating CCL2 was significant and CRP was negligible to explain the presence of AF. The duration of the episode also bore a significant predictive value. Odd ratios for AF as a function of genotype did not differ from 1·0 for any of the individual CRP and CCL2 polymorphisms, or any combinations.

CONCLUSIONS

Elevated plasma CRP concentration per se does not increase atrial fibrillation risk. Values obtained for CCL2 suggest that inflammation is probably a consequence of AF. Our data also suggest that the effect of the duration of the episode should be further studied in the assessment of the actual role of inflammation.

Biomarkers in atrial fibrillation: a clinical review

Assessment of atrial fibrillation (AF)-associated stroke risk is at present mainly based on clinical risk scores such as CHADS2 and CHA2DS2-VASc, although these scores provide only modest discrimination of risk for individual patients. Biomarkers derived from the blood may help refine risk assessment in AF for stroke outcomes and for mortality. Recent studies of biomarkers in AF have shown that they can substantially improve risk stratification. Cardiac biomarkers, such as troponin and natriuretic peptides, significantly improve risk stratification in addition to current clinical risk stratification models. Similar findings have recently been described for markers of renal function, coagulation, and inflammation in AF populations based on large randomized prospective clinical trials or large community-based cohorts. These new findings may enable development of novel tools to improve clinical risk assessment in AF. Biomarkers in AF may also improve the understanding of the pathophysiology of AF further as well as potentially elucidate novel treatment targets. This review will highlight novel associations of biomarkers and outcomes in AF as well as recent progress in the use of biomarkers for risk stratification.

Hormone replacement therapy and risk of new-onset atrial fibrillation after myocardial infarction--a nationwide cohort study

OBJECTIVES

Our aim was to assess the association between use of hormone replacement therapy (HRT) and risk of new-onset atrial fibrillation (AF) after myocardial infarction.

DESIGN, SETTING AND PARTICIPANTS

We used Danish nationwide registers of hospitalizations and prescriptions to identify all women admitted with myocardial infarction in the period 1997 to 2009 and with no known diagnosis of AF. Their use of overall HRT and HRT categories was assessed. Multivariable Cox proportional hazards analysis was used to calculate the risk of new-onset AF first year after discharge, comparing use of HRT to no use.

MAIN OUTCOME MEASURES

New-onset atrial fibrillation.

RESULTS

In the period 1997 to 2009, 32 925 women were discharged alive after MI. In the first year after MI, new-onset AF was diagnosed in 1381 women (4.2%). Unadjusted incidence rates of AF decreased with use of HRT (incidence rate 37.4 for use of overall HRT and 53.7 for no use). Overall HRT was associated with a decreased risk of AF (HR 0.82, 95% confidence interval [CI] 0.68-1.00). The lowest risk of AF was found in women ≥80 years old for use of overall HRT and vaginal estrogen (HR 0.63, CI 0.42-0.94, and HR 0.58, CI 0.34-0.99, respectively). Decreased risk of AF with use of overall HRT and HRT categories was also found in other age groups.

CONCLUSIONS

Use of HRT is associated with a decreased risk of new-onset AF in women with myocardial infarction first year after discharge. The underlying mechanisms remain to be determined. Unmeasured confounding might be one of them.

Trends in the management of atrial fibrillation: A neurologist's perspective

Cardiac embolism, primarily from atrial fibrillation (AF), is implicated in a quarter of all ischemic strokes. In the setting of AF, contraindications to traditional therapies can create a clinical dilemma when choosing an agent for secondary stroke prophylaxis. Newer horizons in the medical and surgical management of AF have helped us choose from a wide variety of available therapies, the best possible management. In this article, we review the current trends in AF management including newer oral anticoagulants as well as surgical devices from a neurologist's view.

Histopathological characteristics and oxidative injury secondary to atrial fibrillation in the left atrial appendages of patients with different forms of mitral valve disease

BACKGROUND

The prevalence of atrial fibrillation (AF) and the frequency cardioversion of AF postoperatively are different in different forms of mitral valve disease. We hypothesized that these differences would relate to different extent of histopathological characteristics and oxidative injury in different forms of mitral valve diseases.

METHODS

Left atrial appendages were obtained from 24 patients of mitral valve disease with or without AF undergoing mitral valve surgery. Control data were obtained from left appendages of 4 persons in normal sinus rhythm (SR) died of traffic accident. Histopathology, immunohistochemistry, Western blotting and enzyme kinetics examination were performed to assess the extent of histopathological characteristics and oxidative injury.

RESULTS

The average cross-sectional diameter of atrial myocyte of mitral stenosis (MS)+AF, MS+SR, mitral regurgitation (MR)+AF, MR+SR and control was 25.62±7.56 μm, 20.20±9.34 μm, 21.69±7.00 μm, 13.93±4.32 μm and 9.81±2.34 μm, respectively. Significantly statistical difference was found between each group (P<.05). Increased degree of atrial interstitial fibrosis was seen both in MS and MR with AF patients compared to other groups (P<.05), and the extent of fibrosis was more remarkable in MR patients compared to MS patients (P<.05). The extent of 3-nitrotyrosine (3-NT) immunoreactivity significantly increased in the patients with MS and AF compared to those of MR and AF (P<.05), and the immunoprevalence of 3-NT was significantly increased in patients of MS and SR compared to those of MR and SR (P<.05). Correlation analysis demonstrated a negative correlation between creatine kinase (CK) activity and extent of 3-NT immunoreactivity in atrial tissues (r=-0.382, P<.05). Significant decreases in CK activity were observed in myocardium from all patients of mitral valve disease with or without AF compared to controls (P<.05). Western blotting demonstrating an increased prevalence of 3-NT formation in CK-MM was detected compared to control group (P<.05). Correlation analysis demonstrated a negative correlation between CK-MM activity and extent of CK-MM tyrosine nitration (r=-0.446, P<.05).

CONCLUSIONS

In different forms of mitral valve disease with different cardiac rhythm, the extent of histopathological characteristics and oxidative injury are different. Histopathological characteristics and oxidative injury not only relate to mitral valve disease but also relate to the development and sustain of AF.

The role of inflammatory markers in atrial fibrillation: a review

This review is focused on the role of latent inflammation in atrial fibrillation (AF) pathogenesis. The modern views and available evidence on the association between the levels of inflammatory markers and AF development and recurrence are presented. The justification for the use of pleiotropic effects of pharmacological therapy in AF prevention and treatment is discussed.

Inflammatory biomarkers as risk factors for future atrial fibrillation. An eleven-year follow-up of 6315 men and women: the Tromsø study

BACKGROUND

Inflammatory biomarkers are reported as risk factors for atrial fibrillation (AF), but their impact is uncertain.

OBJECTIVE

We investigated the associations between inflammatory biomarkers and future AF in a large general cohort.

METHODS

Available markers were white blood cells (WBCs) with subgroups, fibrinogen, high-sensitivity C-reactive protein (hs-CRP), and osteoprotegerin (OPG). A total of 6315 men and women from a population survey in Tromsø, Norway in 1994 to 1995 were followed for a mean of 10.9 years. Mean age at baseline was 60 years. Measurements of height, weight, blood pressure, heart rate, total cholesterol, high-density lipoprotein (HDL) cholesterol, WBC count, and information on diabetes, angina, myocardial infarction, and antihypertensive treatment, were obtained at baseline. Fibrinogen, hs-CRP, and OPG were obtained at a follow-up visit. The outcome measure was first-ever AF, documented on an electrocardiogram. The Cox proportional hazards regression model was used to estimate hazard ratios of AF.

RESULTS

In the multivariable analysis, adjusted for traditional cardiovascular risk factors and other inflammatory biomarkers, hs-CRP was associated with AF in men only (hazard ratio = 1.14 for a 1 SD increase; 95% CI, 1.02-1.28). There was a significant increase in AF across quartiles of WBCs in men (P = 0.007) and in the total study population (P = 0.004). OPG was associated with AF in patients free of coronary heart disease at baseline. Fibrinogen and subgroups of WBCs showed no significant association with AF.

CONCLUSION

This population-based cohort study showed that hs-CRP was independently associated with AF in men, but apparently not in women, and that patients with WBCs in the upper quartile had increased risk of AF.

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.

A preliminary study about the effects of warm priming solution on oxidative stress and postoperative atrial fibrillation in open heart surgery

BACKGROUND

An important reason for production of ischemia and reperfusion injury and oxidative stress is the sudden and rapid changes in body temperature during the institution of cardiopulmonary bypass. The aim of this study was to investigate the effects of warm priming solution on oxidative stress and atrial fibrillation.

METHODS

This is a preliminary prospective study on a group of 40 patients who underwent elective coronary artery bypass grafting operation using cardiopulmonary bypass. Patients were randomized into two groups, each consisting of 20 patients; one group was primed with a solution at 20 °C and the other at 36 °C initially for cardiopulmonary bypass. Blood samples from both of the groups were drawn preoperatively and at the 15th and 60th min of aortic cross clamping and 24th h following the surgery. Serum malondialdehyde levels, protein carbonyl content and total antioxidant status were detected. Patients were followed for postoperative atrial fibrillation.

RESULTS

Malondialdehyde and protein carbonyl content were found to be significantly higher and total antioxidant status was concordantly lower in the cold priming group at the 15th and 60th min, recovering to the normal range postoperatively at the 24th h. Patients in the cold priming group had developed a significantly higher rate of atrial fibrillation when compared with the patients in the warm priming group during the postoperative period.

CONCLUSION

In conclusion, although this study has its limitation about the sample size it may provide an insight about the probable preventive effects of 36 °C warm priming solution in oxidative stress and postoperative atrial fibrillation.

High sensitivity cardiac troponin T and interleukin-6 predict adverse cardiovascular events and mortality in anticoagulated patients with atrial fibrillation

There are limited data on the prognostic role of biomarkers in anticoagulated patients with atrial fibrillation (AF). We evaluated the prognostic value of high sensitivity TnT (hsTnT) and high-sensitivity interleukin-6 (hsIL6) in a large cohort of AF patients taking oral anticoagulant therapy (OAC) as both biomarkers have been associated with adverse cardiovascular events.

METHODS

We studied 930 patients (51% male; median age 76) with permanent/ paroxysmal AF who were stabilized (for at least 6 months) on OAC (INRs 2.0-3.0). Plasma hsTnT and hsIL6 levels were quantified by electrochemiluminescense immunoassay at baseline. Patients were followed-up for up to 2 years, and adverse events (thrombotic and vascular events, mortality and major bleeding) were recorded.

RESULTS

At follow-up, 96 patients (3.97%/year) died whilst 107 had an adverse cardiovascular event (3.14%/year). On multivariate analysis, high hsTnT and high hsIL6 remained significantly associated with prognosis even after adjusting for CHADS2 score: HR 2.21 (1.46-3.35, P<0.001) for high hsTnT and 1.97 (1.29-3.02, P=0.002) for high hsIL6, for adverse cardiovascular events. For all-cause mortality, the HRs were 1.79 (1.13-2.83, P=0.013) and 2.48 (1.60-3.85, P<0.001), respectively. The integrated discrimination index (IDI) values of clinical scores (CHADS2 and CHA2 DS2-VASc) were improved by the addition of hsTnT and/or hsIL6 (all P<0.05).

CONCLUSION

In a large 'real world' cohort of anticoagulated AF patients, both hsTnT and hsIL6 levels provided prognostic information that was complementary to clinical risk scores for prediction of long-term cardiovascular events and death, suggesting that these biomarkers may potentially be used to refine clinical risk stratification in AF.

[Pathogenetic justification of statin use in ischaemic stroke prevention according to inflammatory theory in development of atherosclerosis]

There is an inflammatory component in the pathogenesis of ischaemic stroke, which plays an important role in inducing atherothrombotic and embolic stroke. Statins, HMG-CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase inhibitors are widely used in the primary and secondary prevention of ischaemic stroke. It has been proved that beyond their main effect on inhibition of endogenous cholesterol, they also modify the inflammatory process. Additional benefits from the use of statins result from their effect on the immune system. Increased risk of recurrent vascular episodes and risk of death after statin withdrawal in patients with vascular disorders is connected with termination of the anti-inflammatory effect of these drugs. The authors highlight that because of the anti-inflammatory effect of statins it is reasonable to use them in all patients at risk of ischaemic stroke, including those with atrial fibrillation.

Effect of Sodium Nitroprusside on the Occurrence of Atrial Fibrillation after Cardiothoracic Surgery

BACKGROUND:

Postoperative atrial fibrillation (POAF) is a frequent complication following cardiothoracic surgery and is associated with an increase in morbidity, mortality, and cost. One small prospective study of patients undergoing isolated coronary artery bypass graft surgery has demonstrated a decrease in the risk of POAF with the use of sodium nitroprusside.

OBJECTIVE:

To determine whether there is an association between intraoperative sodium nitroprusside use and the incidence of POAF.

METHODS:

A retrospective cohort of 1025 patients aged 18 years and older who underwent any cardiac surgery between April 2007 and July 2010 was evaluated at Regional Hospital of Scranton. Patients with a history of atrial fibrillation, those who had undergone cardiothoracic surgery, or those undergoing surgical treatment for atrial fibrillation were excluded. The primary outcome was the odds of developing POAF given the utilization of sodium nitroprusside during cardiothoracic surgery. POAF was defined according to the Society of Thoracic Surgeons Adult Cardiac Surgery Database version 2.61 as a new onset of atrial fibrillation/flutter requiring treatment that was not present preoperatively. Data on use of intraoperative sodium nitroprusside were obtained from the pharmacy department's billing database.

RESULTS:

The final analysis included 699 patients; 473 received sodium nitroprusside. The incidence of POAF was 25.4% in the sodium nitroprusside group and 27.9% in the control group. Univariate analysis demonstrated no association of sodium nitroprusside with POAF (OR 0.880; 95% CI 0.615 to 1.257). Multivariate analysis also showed no significant difference in the odds of POAF with sodium nitroprusside (OR 0.827; 95% CI 0.565 to 1.210). Repeating the analysis in 276 propensity score–matched patients also failed to demonstrate any association (OR 0.774; 95% CI 0.454 to 1.319).

CONCLUSIONS:

There was no significant association between the use of sodium nitroprusside during cardiothoracic surgery and POAF.

Relation of hs-CRP and BNP levels with the atrial spontaneous echo contrast and thrombi in permanent atrial fibrillation patients with different etiologies

Background

Thromboembolic risk in permanent atrial fibrillation (AF) is strongly associated with the underlying etiology, and inflammatory parameters may contribute. The present study aimed to investigate the relationship of hs-CRP and BNP levels with left and right atrial appendage (LAA and RAA) function, presence of spontaneous echo contrast (SEC) and thrombus.

Material/Methods

Eighty-four permanent AF patients with different etiologies (20 mitral stenosis, 44 hypertension and 20 hyperthyroidism) and 23 patients with sinus rhythm were included. LAA and RAA flow velocities were measured by pulsed-wave Doppler and wall motion velocities with tissue Doppler imaging (TDI) in transesophageal echocardiography.

Results

Hs-CRP and BNP levels significantly differed among the 3 AF groups: levels were highest in mitral stenosis patients (8.6±5.3 mg/L and 98.0±125.7 pg/mL, respectively), the lowest hs-CRP was in hyperthyroidism patients (4.3±3.8 mg/L), and the lowest BNP was in hypertensive patients (64.8±44.3 pg/mL). There were also significant differences between the AF group and controls regarding hs-CRP and BNP levels. In the correlation analysis, BNP level was not significantly correlated with LAA and RAA functions, whereas hs-CRP level was significantly correlated with some LAA and RAA functions. On the other hand, hs-CRP level was significantly related to the presence of mild-moderate SEC and thrombi, mainly in mitral stenosis patients. Moreover, hs-CRP was the most important determinant of RAA thrombus formation, followed by RAA ejection fraction. In contrast, no positive or negative correlation was found between BNP levels and RAA and LAA thrombi.

Conclusions

Higher hs-CRP levels in AF patients may be a predictor for the presence of SEC and thrombi in the atria.

Fish, fish-derived n-3 fatty acids, and risk of incident atrial fibrillation in the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

Results of observational and experimental studies investigating the association between intake of long-chain n-3 polyunsaturated fatty acids (PUFAs) and risk of atrial fibrillation (AF) have been inconsistent.

METHODS

We studied the association of fish and the fish-derived n-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with the risk of incident AF in individuals aged 45-64 from the Atherosclerosis Risk in Communities (ARIC) cohort (n = 14,222, 27% African Americans). Intake of fish and of DHA and EPA were measured via food frequency questionnaire. Plasma levels of DHA and EPA were measured in phospholipids in a subset of participants (n = 3,757). Incident AF was identified through the end of 2008 using ECGs, hospital discharge codes and death certificates. Cox proportional hazards regression was used to estimate hazard ratios of AF by quartiles of n-3 PUFAs or by fish intake.

RESULTS

During the average follow-up of 17.6 years, 1,604 AF events were identified. In multivariable analyses, total fish intake and dietary DHA and EPA were not associated with AF risk. Higher intake of oily fish and canned tuna was associated with a nonsignificant lower risk of AF (p for trend = 0.09). Phospholipid levels of DHA+EPA were not related to incident AF. However, DHA and EPA showed differential associations with AF risk when analyzed separately, with lower risk of AF in those with higher levels of DHA but no association between EPA levels and AF risk.

CONCLUSIONS

In this racially diverse sample, dietary intake of fish and fish-derived n-3 fatty acids, as well as plasma biomarkers of fish intake, were not associated with AF risk.

Prevention of postoperative atrial fibrillation: novel and safe strategy based on the modulation of the antioxidant system

Postoperative atrial fibrillation (AF) is the most common arrhythmia following cardiac surgery with extracorporeal circulation. The pathogenesis of postoperative AF is multifactorial. Oxidative stress, caused by the unavoidable ischemia-reperfusion event occurring in this setting, is a major contributory factor. Reactive oxygen species (ROS)-derived effects could result in lipid peroxidation, protein carbonylation, or DNA oxidation of cardiac tissue, thus leading to functional and structural myocardial remodeling. The vulnerability of myocardial tissue to the oxidative challenge is also dependent on the activity of the antioxidant system. High ROS levels, overwhelming this system, should result in deleterious cellular effects, such as the induction of necrosis, apoptosis, or autophagy. Nevertheless, tissue exposure to low to moderate ROS levels could trigger a survival response with a trend to reinforce the antioxidant defense system. Administration of n-3 polyunsaturated fatty acids (PUFA), known to involve a moderate ROS production, is consistent with a diminished vulnerability to the development of postoperative AF. Accordingly, supplementation of n-3 PUFA successfully reduced the incidence of postoperative AF after coronary bypass grafting. This response is due to an up-regulation of antioxidant enzymes, as shown in experimental models. In turn, non-enzymatic antioxidant reinforcement through vitamin C administration prior to cardiac surgery has also reduced the postoperative AF incidence. Therefore, it should be expected that a mixed therapy result in an improvement of the cardioprotective effect by modulating both components of the antioxidant system. We present novel available evidence supporting the hypothesis of an effective prevention of postoperative AF including a two-step therapeutic strategy: n-3 PUFA followed by vitamin C supplementation to patients scheduled for cardiac surgery with extracorporeal circulation. The present study should encourage the design of clinical trials aimed to test the efficacy of this strategy to offer new therapeutic opportunities to patients challenged by ischemia-reperfusion events not solely in heart, but also in other organs such as kidney or liver in transplantation surgeries.

Relation of left atrial spontaneous echocardiographic contrast in patients with mitral stenosis to inflammatory markers

Spontaneous echocardiographic contrast (SEC) is the presence of smoke-like echoes with a characteristic swirling motion of blood in echocardiography. Previous clinical studies have demonstrated that SEC is a risk factor for left atrial thrombus formation and an important indicator of potential systemic embolism originated from heart. An established relation exists between the inflammatory status and the prothrombotic state. Therefore, we investigated the role of inflammatory status on SEC in patients with mitral stenosis (MS). A total of 62 consecutive patients with MS who undergoing mitral balloon valvuloplasty were enrolled in the present study. The patients were divided into 2 groups according to the formation of SEC in the left atrium. Of the 62 patients, 32 (mean age 45 ± 12 years; 75% women) were in the SEC-negative group and 30 patients (mean age 45 ± 11 years; 63% women) were in the SEC-positive group. The high-sensitive C-reactive protein levels were significantly greater in the SEC-positive group than in the SEC-negative group (3.9 ± 2.2 vs 10.6 ± 6.3, p = 0.024). The neutrophil levels (64.6 ± 9.4 vs 72.6 ± 8.6) were significantly greater in the SEC-positive group, and the lymphocyte levels (24.4 ± 6.9 vs 18.3 ± 6.0) were significantly greater in the SEC-negative group (p = 0.001 for each). The neutrophil/lymphocyte (N/L) ratio was also significantly greater in the SEC-positive group (3.0 ± 1.8 vs 4.5 ± 1.8, p = 0.003). In the receiver operating characteristics curve analysis, a N/L ratio > 3.1 mg/dl had a 80% sensitivity and 72% specificity in predicting SEC in patients with MS. On multivariate analysis, high-sensitive C-reactive protein (odds ratio [OR] 1.235, 95% confidence interval [CI] 1.040 to 1.466; p = 0.016), N/L ratio (OR 1.461, 95% CI 0.977 to 2.184; p = 0.02), left atrial volume (OR 3.012, 95% CI 1.501 to 5.611; p = 0.001), and mitral valve area (OR 0.135, 95% CI 0.020 to 0.503; p = 0.017) were independent risk factors of SEC in patients with MS. In conclusion, the high-sensitive C-reactive protein and N/L ratio were independently associated with SEC in patients with MS.

N-Acetylcysteine supplementation for the prevention of atrial fibrillation after cardiac surgery: a meta-analysis of eight randomized controlled trials

BACKGROUND

Atrial fibrillation is the most common type of arrhythmia after cardiac surgery. An increasing body of evidence demonstrates that oxidative stress plays a pivotal role in the pathophysiology of atrial fibrillation. N-acetylcysteine (NAC) is a free radical scavenger, and may attenuate this pathophysiologic response and reduce the incidence of postoperative AF (POAF). However, it is unclear whether NAC could effectively prevent POAF. Therefore, this meta-analysis aims to assess the efficacy of NAC supplementation on the prevention of POAF.

METHODS

Medline and Embase were systematically reviewed for studies published up to November 2011, in which NAC was compared with controls for adult patients undergoing cardiac surgery. Outcome measures comprised the incidence of POAF and hospital length of stay (LOS). The meta-analysis was performed with the fixed-effect model or random-effect model according to the heterogeneity.

RESULTS

Eight randomized trials incorporating 578 patients provided the best evidence and were included in this meta-analysis. NAC supplementation significantly reduced the incidence of POAF (OR 0.62, 95% CI 0.41 to 0.93; P = 0.021) compared with controls, but had no effect on LOS (WMD -0.07, 95% CI -0.42 to 0.28; P = 0.703).

CONCLUSIONS

The prophylactic NAC supplementation may effectively reduce the incidence of POAF. However, the overall quality of current studies is poor and further research should focus on adequately powered randomized controlled trials with POAF incidence as a primary outcome measure.