Circulating adiponectin levels in patients with atrial fibrillation

Association of adiponectin gene expression with atrial fibrillation in a Pakistani populace

Adiponectin, an adipocytokine produced and secreted by adipose tissue, has anti-diabetic, anti-atherogenic, and anti-inflammatory properties. This case-control study was aimed to assess the expression and serum levels of adiponectin in subject suffereing from atrial fibrillation (AF). The study's subjects (n = 690) were enrolled from the Punjab Institute of Cardiology, Lahore and were grouped into control, AF without Metabolic syndrome (MetS), and AF with MetS groups. Along with the collection of demographic data, an analysis of adiponectin and biochemical parameters were performed. A highly significant difference in serum levels of adiponectin was observed among the control, AF without MetS, and AF with MetS groups (61.61 ± 45.30 ng/ml, 37.20 ± 19.46 ng/ml, 63.78 ± 61.69 ng/ml). The expression analysis of adiponectin was decreased (n-fold = ̴ 0.30) in AF without MetS group as compared to control group (n-fold =  ~ 1.16) but increased in AF with MetS group (n-fold = ̴ 6.26). The correlation analysis revealed a highly significant positive relationship between the expression of the adiponectin gene with waist-to-hip ratio (WHR) in AF without MetS group. Whereas, serum adiponectin was negatively related to serum triglycerides (TG) in AF with MetS group. In multiple regression analysis using adiponectin expression as the dependent variable, WHR was a determinant in AF without MetS. Whereas, when serum adiponectin was used as the dependent variable, serum TG was the determinant in group AF with MetS. The present study implicates that decreased expression and serum levels of adiponectin were associated with the development of AF in which WHR and serum TG also contributed towards the onset of atrial fibrillation.

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

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

Pathophysiological role of major adipokines in Atrial Fibrillation

Background

The adipokines, secreted from adipose tissue or body fats, are also called adipocytokines which are cytokines, cell signaling proteins or cell–cell communication. However, AF is a common cardiac arrhythmia in which the heart beats so fast by abnormal beating and is a serious public health disease associated with increased heart failure, systemic thromboembolism, and death. Adipokines are cardiovascular disease (CVD) mediators or biomarkers that affect the heart as well as blood vessels, by increasing the cardiac contractility and action potential duration, which result in the extent of left ventricular and atrial remodeling.

Main body

Google Scholar, PubMed, and science direct were used to review the literature. Many keywords were used for searching the literature such as Adipokines, Leptin, Apelin, Adiponectin, Omentin-1, Chemerin, CTRP3, TNF-α, IL-6, IL-10, and AF. According to the literature, much more data are available for numerous adipokines, but this review article only has taken few major adipokines which played their major role in Atrial Fibrillation. The review article did not limit the time frame.

Conclusion

In conclusion, adipokines play a significant role in the development and progress of atrial fibrillation. Also, there are major adipokines such as adiponectin, apelin, C1q/TNF-Related Protein 3 (CTRP3), Chemerin, Omentin-1, interleukin-6, Leptin, TNF-α, resistin, and interleukin-10, which played their pathophysiological role in atrial fibrillation by causing cardiac hypertrophy, increasing the cardiac contractility and action potential duration, atrial fibrosis, electrical and structural remodeling of atrial tissue.

Association between adiponectin-to-leptin ratio and heart rate variability in new-onset paroxysmal atrial fibrillation: A retrospective cohort study

Background

The adiponectin‐to‐leptin (A/L) ratio has been identified as a potential surrogate biomarker for metabolic disorders. However, it remains unknown whether the serum A/L ratio is associated with heart rate variability in paroxysmal atrial fibrillation (AF).

Methods

For this retrospective study, we included consecutive patients who underwent 24‐h long‐range electrocardiogram examination in our center for paroxysmal AF. The results of echocardiography, heart rate variability tests, and blood tests were also retrieved. Multivariate line regression analysis was performed to evaluate identify factors independently associated with heart rate variability.

Results

Among the 85 included patients with paroxysmal AF, the median A/L ratio was 1.71. Univariate analysis indicated that patients with a low A/L ratio (<1.71, n = 42) had a lower high‐frequency (HF) power and a higher hs‐CRP level, low‐frequency (LF) power, and LF/HF ratio than those with a high A/L ratio (≥1.71, n = 43). Multivariate linear regression analysis showed that the serum leptin concentration was independently and positively associated with LF (β = 0.175, p = .028), while the serum adiponectin concentration was independently and positively associated with HF (β = 0.321, p = .001). Moreover, the A/L ratio was independently and negatively associated with the LF/HF ratio (β = −0.276, p = .007).

Conclusions

The A/L ratio was independently and negatively associated with the LF/HF ratio in patients with new‐onset paroxysmal AF.

Association between Serum Adiponectin and Atrial Fibrillation: A Case-Control Study Stratified by Age and Gender

Background

Circulating adiponectin has been suggested to be associated with atrial fibrillation (AF). However, whether the association differs by age and gender remains unknown. We performed a case-control study to evaluate the above association.

Methods

AF patients who underwent 24-hour long-range 12-channel electrocardiogram examination at our center were included in this study, and people with normal sinus rhythm (NSR) were included as controls. All participants underwent echocardiography and heart rate variability tests. Biochemical parameters and adiponectin levels were also evaluated. Receiver operating characteristic (ROC) analyses were used to determine the predictive efficacy of adiponectin for AF, and multivariate logistic regression analysis was performed to evaluate the potential independent predictors of AF.

Results

Overall, 84 patients with AF and 84 people with NSR were included. Serum adiponectin was significantly higher in AF patients compared to that in controls (P < 0.001). ROC analysis showed that higher serum adiponectin (>6.098 μg/mL) had predictive efficacy for AF, with an area under the curve of 0.660 (95% confidence interval [CI]: 577–0.742). The results of multivariate logistic regression analysis showed that higher adiponectin was an independent predictor of AF in the overall participants (odds ratio [OR] 1.224, 95% CI 1.018–1.471, P=0.032). Subgroup analysis showed that higher adiponectin was independently associated with AF in women (OR 1.893, 95% CI 1.160–3.089, P=0.011) and in patients aged < 65 years (OR 1.453, 95% CI 1.023–2.064, P=0.037), but not in men or those aged ≥ 65 years.

Conclusions

Higher serum adiponectin level was independently associated with higher odds for AF in women and in participants <65 years old, but not in men or those aged ≥65 years.

Association of Plasma C1q/TNF-Related Protein 3 (CTRP3) in Patients with Atrial Fibrillation

Atrial fibrillation (AF) is a highly prevalent cardiac arrhythmia characterized by atrial remodeling. Complement C1q tumor necrosis factor-related protein 3 (CTRP3) is one of the adipokines associated with obesity, diabetes, and coronary heart disease. The association between plasma CTRP3 levels and AF is uncertain. The aim of this study was to investigate whether plasma CTRP3 concentrations were correlated with AF. Our study included 75 AF patients who underwent catheter ablation at our hospital and 47 sinus rhythm patients to determine the difference in plasma CTRP3 concentrations. Blood samples before the ablation were collected, and ELISA was used to measure the concentrations of CTRP3. Plasma CTRP3 concentrations were significantly lower in AF patients compared with control group (366.9 ± 105.2 ng/ml vs. 429.1 ± 100.1 ng/ml, p = 0.002). In subgroup studies, patients with persistent AF had lower plasma CTRP3 concentrations than those with paroxysmal AF (328.3 ± 83.3 ng/ml vs. 380.0 ± 109.2 ng/ml, p = 0.037). The concentrations of plasma CTRP3 in the recurrence group after radiofrequency catheter ablation of AF were lower than those in the nonrecurrence group (337.9 ± 77.3 ng/ml vs. 386.6 ± 108.1 ng/ml, p = 0.045). Multivariate regression analysis revealed the independent correlation between plasma CTRP3 level and AF. Plasma CTRP3 concentrations were correlated with the presence of AF and AF recurrence.

Opposite relations of epicardial adipose tissue to left atrial size in paroxysmal and permanent atrial fibrillation

Objectives:

Atrial fibrillation has been associated with obesity in epidemiological studies. Epicardial adipose tissue is an ectopic fat depot in the proximity of atria, with endocrine and inflammatory properties that is implicated in the pathophysiology of atrial fibrillation. Inflammation also has a role in atrial arrhythmogenesis. The aim of this study was to investigate the potential relations of epicardial adipose tissue to left atrial size and to adiponectin and the pro-inflammatory mediators, high-sensitivity C-reactive protein, and interleukin-6 in paroxysmal and permanent atrial fibrillation.

Methods:

This was a cross-sectional study of 103 atrial fibrillation patients, divided into two subgroups of paroxysmal and permanent atrial fibrillation, and 81 controls, in sinus rhythm. Echocardiography was used for estimation of epicardial adipose tissue and left atrial size and high-sensitivity C-reactive protein, interleukin-6 and adiponectin were measured in all subjects.

Results:

Atrial fibrillation patients had significantly larger epicardial adipose tissue compared with controls (0.43 ± 0.17 vs 0.34 ± 0.17 cm, p = 0.002). Atrial fibrillation presence was independently related to epicardial adipose tissue thickness (b = 0.09, p = 0.002). Opposite associations of epicardial adipose tissue with left atrial volume existed in atrial fibrillation subgroups; in the paroxysmal subgroup, epicardial adipose tissue was directly related to left atrial volume (R = 0.3, p = 0.03), but in the permanent one the relation was inverse (R = −0.7, p < 0.0001). Adiponectin, high-sensitivity C-reactive protein and interleukin-6 were elevated in both atrial fibrillation groups. Only interleukin-6 was related to epicardial adipose tissue size.

Conclusion:

Opposite associations of epicardial adipose tissue with left atrial size in paroxysmal and permanent Atrial fibrillation and elevated inflammatory markers, suggest a role of epicardial adipose tissue and inflammation in the fibrotic and remodeling process.

Validation of a proteomic biomarker panel to diagnose minor-stroke and transient ischaemic attack: phase 2 of SpecTRA, a large scale translational study

OBJECTIVE

To validate our previously developed 16 plasma-protein biomarker panel to differentiate between transient ischaemic attack (TIA) and non-cerebrovascular emergency department (ED) patients.

METHOD

Two consecutive cohorts of ED patients prospectively enrolled at two urban medical centers into the second phase of SpecTRA study (training, cohort 2A, n = 575; test, cohort 2B, n = 528). Plasma samples were analyzed using liquid chromatography/multiple reaction monitoring-mass spectrometry. Logistic regression models which fit cohort 2A were validated on cohort 2B.

RESULTS

Three of the panel proteins failed quality control and were removed from the panel. During validation, panel models did not outperform a simple motor/speech (M/S) deficit variable. Post-hoc analyses suggested the measured behaviour of L-selectin and coagulation factor V contributed to poor model performance. Removal of these proteins increased the external performance of a model containing the panel and the M/S variable.

CONCLUSIONS

Univariate analyses suggest insulin-like growth factor-binding protein 3 and serum paraoxonase/lactonase 3 are reliable and reproducible biomarkers for TIA status. Logistic regression models indicated L-selectin, apolipoprotein B-100, coagulation factor IX, and thrombospondin-1 to be significant multivariate predictors of TIA. We discuss multivariate feature subset analyses as an exploratory technique to better understand a panel's full predictive potential.

Verification of a proteomic biomarker panel to diagnose minor stroke and transient ischaemic attack: phase 1 of SpecTRA, a large scale translational study

OBJECTIVE

To derive a plasma biomarker protein panel from a list of 141 candidate proteins which can differentiate transient ischaemic attack (TIA)/minor stroke from non-cerebrovascular (mimic) conditions in emergency department (ED) settings.

DESIGN

Prospective clinical study (#NCT03050099) with up to three timed blood draws no more than 36 h following symptom onset. Plasma samples analysed by multiple reaction monitoring-mass spectrometry (MRM-MS).

PARTICIPANTS

Totally 545 participants suspected of TIA enrolled in the EDs of two urban medical centres.

OUTCOMES

90-day, neurologist-adjudicated diagnosis of TIA informed by clinical and radiological investigations.

RESULTS

The final protein panel consists of 16 proteins whose patterns show differential abundance between TIA and mimic patients. Nine of the proteins were significant univariate predictors of TIA [odds ratio (95% confidence interval)]: L-selectin [0.726 (0.596-0.883)]; Insulin-like growth factor-binding protein 3 [0.727 (0.594-0.889)]; Coagulation factor X [0.740 (0.603-0.908)]; Serum paraoxonase/lactonase 3 [0.763 (0.630-0.924)]; Thrombospondin-1 [1.313 (1.081-1.595)]; Hyaluronan-binding protein 2 [0.776 (0.637-0.945)]; Heparin cofactor 2 [0.775 (0.634-0.947)]; Apolipoprotein B-100 [1.249 (1.037-1.503)]; and von Willebrand factor [1.256 (1.034-1.527)]. The scientific plausibility of the panel proteins is discussed.

CONCLUSIONS

Our panel has the potential to assist ED physicians in distinguishing TIA from mimic patients.

Clinical implications of serum adiponectin on progression of atrial fibrillation

Background

The association between circulating adiponectin levels and atrial fibrillation (AF) is uncertain. We, therefore, investigated whether an increased serum adiponectin level is implicated in the long-term recurrence of AF after ablation therapy.

Methods

Our study included 100 consecutive patients (88 men; median age, 57.9±10.9 years) who underwent catheter ablation for AF at our hospital between 2011 and 2013. The adiponectin and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were measured before ablation and compared between those in whom AF recurred and those in whom AF did not recur.

Results

Elevation in adiponectin levels was significantly associated with female sex, non-paroxysmal AF, heart failure, higher NT-proBNP and matrix metallo-proteinase-2 levels, and lower body mass index. After a stepwise adjustment for any potential confounding variables, the adiponectin levels remained significantly associated with female sex (beta=0.2601, P=0.0041), non-paroxysmal AF (beta=0.2708, P=0.0080), and higher NT-proBNP levels (beta=0.2536, P= 0.0138). During the median follow-up period of 26.2 months, AF recurred in 48 of the 100 patients. Stepwise multivariate adjustment showed that an increased log-transformed NT-proBNP (Hazard ratio [HR], 2.18; 95% confidence interval [CI] 1.25-4.00; P=0.0055), longer duration of AF (HR, 1.87; 95%CI 1.01-3.76; P=0.0465), and decreased left ventricular ejection fraction (HR, 0.96; 95%CI 0.93-0.99; P=0.0391) were independent predictors of recurrent AF after catheter ablation, but adiponectin was not.

Conclusions

Our data indicated that adiponectin was partially responsible for progression of AF, but the correlation between adiponectin levels and AF recurrence was not significant.

Linking atrial fibrillation with non-alcoholic fatty liver disease: potential common therapeutic targets

Non-alcoholic fatty liver disease (NAFLD) and atrial fibrillation (AF) are common chronic non-infectious diseases with rising incidences. NAFLD is an independent risk factor for the onset of AF, after adjusting potentially related factors. The pathogenesis of these diseases share several mechanisms including reduced adiponectin level, insulin resistance, and renin angiotensin aldosterone system (RAAS) activation, in addition to activation of common disease pathways that promote inflammation, oxidative stress, and fibrosis. Furthermore, statins and RAAS blockers exert therapeutic effects concurrently on NAFLD and AF. The common pathogenesis of NAFLD and AF may serve as a potential therapeutic target in the future.

The associations of leptin, adiponectin and resistin with incident atrial fibrillation in women

OBJECTIVES

Higher body mass index (BMI) is an important risk factor for atrial fibrillation (AF). The adipokines leptin, adiponectin and resistin are correlates of BMI, but their association with incident AF is not well known. We explored this relationship in a large cohort of postmenopausal women.

METHODS

We studied an ethnically diverse cohort of community-dwelling postmenopausal women aged 50-79 who were nationally recruited at 40 clinical centres as part of the Women's Health Initiative investigation. Participants underwent measurements of baseline serum leptin, adiponectin and resistin levels and were followed for incident AF. Adipokine levels were log transformed and normalised using inverse probability weighting. Cox proportional hazard regression models were used to estimate associations with adjustment for known AF risk factors.

RESULTS

Of the 4937 participants included, 892 developed AF over a follow-up of 11.1 years. Those with AF had higher mean leptin (14.9 pg/mL vs 13.9 pg/mL), adiponectin (26.3 ug/mL vs 24.5 ug/mL) and resistin (12.9 ng/mL vs 12.1 ng/mL) levels. After multivariable adjustment, neither log leptin nor log adiponectin levels were significantly associated with incident AF. However, log resistin levels remained significantly associated with incident AF (HR=1.57 per 1 log (ng/mL) increase, p=0.006). Additional adjustment for inflammatory cytokines only partially attenuated the association between resistin and incident AF (HR=1.43, p=0.06 adjusting for C-reactive protein (CRP); HR=1.39, p=0.08 adjusting for IL-6). Adjusting for resistin partially attenuated the association between BMI and incident AF (HR=1.14 per 5 kg/m(2), p=0.006 without resistin; HR=1.12, p=0.02 with resistin).

CONCLUSIONS

In women, elevated levels of serum resistin are significantly associated with higher rates of incident AF and partially mediate the association between BMI and AF. In the same population, leptin and adiponectin levels are not significantly associated with AF.

Class I Histone Deacetylase Inhibition for the Treatment of Sustained Atrial Fibrillation

Current therapies are less effective for treating sustained/permanent versus paroxysmal atrial fibrillation (AF). We and others have previously shown that histone deacetylase (HDAC) inhibition reverses structural and electrical atrial remodeling in mice with inducible, paroxysmal-like AF. Here, we hypothesize an important, specific role for class I HDACs in determining structural atrial alterations during sustained AF. The class I HDAC inhibitor N-acetyldinaline [4-(acetylamino)-N-(2-amino-phenyl) benzamide] (CI-994) was administered for 2 weeks (1 mg/kg/day) to Hopx transgenic mice with atrial remodeling and inducible AF and to dogs with atrial tachypacing-induced sustained AF. Class I HDAC inhibition prevented atrial fibrosis and arrhythmia inducibility in mice. Dogs were divided into three groups: 1) sinus rhythm, 2) sustained AF plus vehicle, and 3) sustained AF plus CI-994. In group 3, the time in AF over 2 weeks was reduced by 30% compared with group 2, along with attenuated atrial fibrosis and intra-atrial adipocyte infiltration. Moreover, group 2 dogs had higher atrial and serum inflammatory cytokines, adipokines, and atrial immune cells and adipocytes compared with groups 1 and 3. On the other hand, groups 2 and 3 displayed similar left atrial size, ventricular function, and mitral regurgitation. Importantly, the same histologic alterations found in dogs with sustained AF and reversed by CI-994 were also present in atrial tissue from transplanted patients with chronic AF. This is the first evidence that, in sustained AF, class I HDAC inhibition can reduce the total time of fibrillation, atrial fibrosis, intra-atrial adipocytes, and immune cell infiltration without significant effects on cardiac function.

Prevalence of Atrial Fibrillation and Relation to Echocardiographic Parameters in a Healthy Asymptomatic Rural Korean Population

Atrial fibrillation (AF) is the most common arrhythmia worldwide and a potent independent risk factor for stroke. This study aimed to determine the prevalence of AF in a population-based sample of adults in a rural region of Korea. Between January 2005 and December 2009, 4,067 individuals (60.2 ± 11.2 yr old, M: F = 1,582:2,485) over 21 who were residents of the county of Yangpyeong, Korea, participated in the study. AF was assessed on a resting 12-lead electrocardiogram (ECG) in 4,053 of the participants. Blood tests and transthoracic echocardiography (TTE) were also performed to investigate the relationship between left ventricular mass and AF in the study group. Fifty-four cases (32 men) were diagnosed as AF among the 4,053 subjects. The crude prevalence of AF was 1.3%. It was highest (2.3%) among sixty- and seventy- year olds, and higher in men than women in all age groups over 50. The prevalence in men was 2.0%, and in women 0.9%. In univariate analysis, age, male gender, body mass index, total serum cholesterol, alanine transaminase, serum creatinine, adiponectin level, and ischemic heart disease were associated with AF. Among the TTE parameters, systolic and diastolic left ventricular systolic internal dimension (LVID), and LV ejection fraction were associated with AF. In this relatively healthy population in a rural area of Korea, the prevalence of AF is 1.3%, and increases with age. Of the TTE parameters, systolic and diastolic LVID and left atrial diameter are related to prevalence of AF.

Atrial fibrillation and rapid acute pacing regulate adipocyte/adipositas-related gene expression in the atria

PURPOSE

Atrial fibrillation (AF) has been associated with increased volumes of epicardial fat and atrial adipocyte accumulation. Underlying mechanisms are not well understood. This study aims to identify rapid atrial pacing (RAP)/AF-dependent changes in atrial adipocyte/adipositas-related gene expression (AARE).

METHODS

Right atrial (RA) and adjacent epicardial adipose tissue (EAT) samples were obtained from 26 patients; 13 with AF, 13 in sinus rhythm (SR). Left atrial (LA) samples were obtained from 9 pigs (5 RAP, 4 sham-operated controls). AARE was analyzed using microarrays and RT-qPCR. The impact of diabetes/obesity on gene expression was additionally determined in RA samples (RAP ex vivo and controls) from 3 vs. 6 months old ZDF rats.

RESULTS

RAP in vivo of pigs resulted in substantial changes of AARE, with 66 genes being up- and 53 down-regulated on the mRNA level. Differential expression during adipocyte differentiation was confirmed using 3T3-L1 cells. In patients with AF (compared to SR), a comparable change in RA mRNA levels concerned a fraction of genes only (RETN, IGF1, HK2, PYGM, LOX, and NR4A3). RA and EAT were affected by AF to a different extent. In patients, concomitant disease contributes to AARE changes.

CONCLUSIONS

RAP, and to lesser extent AF, provoke significant changes in atrial AARE. In chronic AF, activation of this gene panel is very likely mediated by AF itself, AF risk factors and concomitant diseases. This may facilitate the development of an AF substrate by increasing atrial ectopic fat and fat infiltration of the atrial myocardium.

The impact of gender and left atrial blood stasis on adiponectin levels in non-valvular atrial fibrillation

BACKGROUND

Obesity is a risk factor for non-valvular atrial fibrillation (NVAF), diabetes mellitus, and hypertension. Adiponectin, a unique biomarker of adipose tissue, has antiinflammatory, insulin-sensitizing, and antiatherogenic properties and is known to be higher in women. The relationship between adiponectin, gender, and thromboembolic risk in atrial fibrillation however is unknown.

METHODS

The relationship between gender, adiponectin levels, and echocardiographic measures of blood stagnation and left atrial appendage thrombus (LAAT) was assessed in 209 patients with NVAF (55 women and 154 men; mean age 63 ± 14 years) compared to 70 normal sinus rhythm controls (29 women and 41 men; mean age 64 ± 14 years). Total adiponectin was measured by solid-phase ELISA. Demographic and clinical variables of CHADS2 and CHA2DS2-VASc were collected, and spontaneous echocardiographic contrast (SEC), left atrial appendage emptying velocity (LAAEV) and left atrium volume index (LAVI) were measured prospectively.

RESULTS

Elevated adiponectin was associated with advanced cardiovascular pathology and permanent arrhythmia but only in men with NVAF. In NVAF men, a step-wise increase in adiponectin levels was noted relative to increasing intensity of SEC and decreasing LAAEV. Adiponectin level >16657 ng/ml predicted LAAT (OR: 3.66; 95% Cl: 1.21-11.48; p=0.022) after adjustment for CHADS2 score in men but not in women with NVAF.

CONCLUSIONS

There is a direct correlation between elevated adiponectin level and the degree of left atrial blood stasis in men but not in women with NVAF. High adiponectin levels can be used as an important variable in the prediction of LAAT.

Significance of plasma adiponectin for diagnosis, neurological severity and functional outcome in ischemic stroke - Research for Biomarkers in Ischemic Stroke (REBIOS)

OBJECTIVE

Although adiponectin is a major adipocytokine that affects the pathogenesis of various cardiovascular diseases, its clinical significance in stroke remains controversial. We investigated the clinical significance of plasma adiponectin for the diagnosis, neurological severity and functional outcomes of patients with ischemic stroke.

METHODS

We prospectively enrolled 171 patients with ischemic stroke and 171 age- and sex-matched healthy controls. Blood samples and clinical information were obtained at day 0, 3, 7, 14 and 90 after stroke onset.

RESULTS

Average adiponectin values at day 0 did not significantly differ between the controls and the patients, but were significantly lower and higher in patients with atherothrombotic brain (ATBI) (p=0.047) and cardioembolic (CE) (p=0.008) infarction, respectively, than in the controls. Multivariate logistic regression analyses showed that the adiponectin value at day 0 could predict ATBI (odds ratio, 0.75; 95% confidence interval, 0.58 to 0.91, p=0.009, per 1-μg/mL increase). Adiponectin values at day 0 were positively associated with neurological severity as evaluated by the National Institute of Health Stroke Scale upon admission (r=0.420, p=0.003) and were higher in the groups with poor outcomes (modified Rankin Scale (mRS) ≥ 3 on day 90) than in those with good ones (mRS ≤ 2) in all stroke subtypes, with statistical significance in ATBI (p=0.015).

CONCLUSIONS

Plasma adiponectin values may help to classify stroke subtypes and predict neurological severity and functional outcome in ischemic stroke patients.

Atrial fibrillation and biomarkers of myocardial fibrosis in heart failure

OBJECTIVES

Alterations of collagen metabolism present in heart failure promote the fibrotic substrate for the development of atrial fibrillation (AF). Myocardial collagen I synthesis and degradation can be assessed indirectly by circulating biomarkers such as the carboxy terminal propeptide (PICP) and carboxy-terminal telopeptide (CITP), respectively.

DESIGN

We examined myocardial collagen type-I metabolism in 143 patients with systolic heart failure (New York Heart Association Class 2-4) in relation to coexisting AF.

RESULTS

Mean age was 75 years, blood pressure 134/80 mm Hg, ejection fraction 34%, serum PICP 81 μg/L and CITP 8.3 μg/L, and median plasma brain natriuretic peptide 215 pg/L; 77 were in AF. PICP and CITP were related to left atrial diameter (r = 0.22, P = 0.013, and r = 0.26, P = 0.003) and CITP to pulmonary capillary wedge pressure and C-reactive protein (r = 0.19, P = 0.044, and r = 0.29, P = 0.003). A logistic regression suggested that PICP (odds ratio per 1 μg/L change 1.01, P = 0.012) and left ventricular end-diastolic volume (odds ratio per 1 mL change 0.98, P < 0.001) were independently associated with coexisting AF.

CONCLUSION

Collagen type-I metabolism is associated to left atrial size. Heart failure patients with coexisting AF exhibit more altered collagen type-I metabolism than patients in sinus rhythm. This might represent more severe atrial and ventricular fibrosis.

Circulating fibrosis biomarkers and risk of atrial fibrillation: The Cardiovascular Health Study (CHS)

BACKGROUND

Cardiac fibrosis is thought to play a central role in the pathogenesis of atrial fibrillation (AF). Retrospective studies have suggested that circulating fibrosis biomarkers are associated with AF, but prospective studies are limited.

METHODS

We measured circulating levels of 2 fibrosis biomarkers, procollagen type III, N-terminal propeptide (PIIINP) and transforming growth factor β1 among participants of the CHS, a population-based study of older Americans. We used Cox proportional hazards and competing risks models to examine adjusted risk of incident AF over a median follow-up of 8.8 years.

RESULTS

Levels of PIIINP were assessed in 2,935 participants, of whom 767 developed AF. Compared with the median PIIINP level (4.45 μg/L), adjusted hazard ratios (95% CIs) were 0.85 (0.72-1.00) at the 10th percentile, 0.93 (0.88-0.99) at the 25th percentile, 1.04 (0.95-1.04) at the 75th percentile, and 1.07 (0.90-1.26) at the 90th. Transforming growth factor β1 levels, assessed in 1,538 participants with 408 cases of incident AF, were not associated with AF risk.

CONCLUSION

In older adults, PIIINP levels were associated with risk of incident AF in a complex manner, with an association that appeared to be positive up to median levels but with little relationship beyond that. Further studies are required to confirm and possibly delineate the mechanism for this relationship.

Cardioembolic stroke diagnosis using blood biomarkers

Stroke is one of the main causes of death and disability in the world. Cardioembolic etiology accounts for approximately one fifth of all ischemic strokes whereas 25-30% remains undetermined even after an advanced diagnostic workup. Despite there is not any biomarker currently approved to distinguish cardioembolic stroke among other etiologies in clinical practice the use of biomarkers represents a promising valuable complement to determine stroke etiology reducing the number of cryptogenic strokes and aiding in the prescription of the most appropriated primary and secondary treatments in order to minimize therapeutic risks and to avoid recurrences. In this review we present an update about specific cardioembolic stroke-related biomarkers at a protein, transcriptomic and genetic level. Finally, we also focused on reported biomarkers associated with atrial fibrillation (a cardiac illness strongly related with cardioembolic stroke subtype) thus with a potential to become biomarkers to detect cardioembolic stroke in the future.

Biomarkers in atrial fibrillation: an overview

Atrial fibrillation (AF) confers a raised risk of stroke and death, and this risk of adverse events is increased by the coexistence of other cardiovascular risk factors. The pathophysiology of AF is complex, involving the role of inflammation, structural remodelling with apoptosis, inflammation or fibrosis. These changes confer a prothrombotic or hypercoagulable state in this arrhythmia. Despite being easy to use for decision-making concerning oral anticoagulant therapy in AF, clinical risk scores used for stratification have shown modest capability in predicting thromboembolic events, and biomarkers may improve our identification of 'high risk' patients. Biomarkers, whether measured in the peripheral blood, urine or imaging-based may improve our knowledge of the pathophysiology of AF. Importantly these biomarkers could help in the assessment of AF prognosis. The aim of this review was to summarise the published data about biomarkers studied in AF, with focus on data from randomised prospective clinical trials and large community-based cohorts. We will also review the application of these biomarkers to prognosis on the main schemes used to help stratify risk in AF.

Total adiponectin is inversely associated with platelet activation and CHA₂DS₂-VASc score in anticoagulated patients with atrial fibrillation

Background. Adiponectin (APN) possesses anti-inflammatory and antiatherogenic effects. Atrial fibrillation (AF) is burdened by enhanced systemic inflammation and platelet activation, as documented by increased blood levels of soluble CD40L (sCD40L). The interplay between APN and platelet activation in AF is still undefined. Materials and Methods. Circulating levels of APN and sCD40L were measured in 257 anticoagulated nonvalvular AF patients. Exclusion criteria were as follows: prosthetic heart valves, cardiac revascularization in the previous year, severe cognitive impairment, chronic infectious or autoimmune diseases, and active cancer. Results. Mean age was 72.9 (±8.7) years and 41.6% were female. Serum APN and plasmatic sCD40L were inversely correlated (R −0.626, P < 0.001). A progressive increase of sCD40L across tertiles of CHA₂DS₂-VASc score was observed (rS 0.473, P < 0.001), whilst APN was inversely correlated (rS −0.463,  P < 0.001). A multivariable linear regression analysis showed that CHA₂DS₂-VASc score (B −0.227, P < 0.001) and sCD40L (B −0.524, P < 0.001) correlated to APN. Conclusions. AF patients at high risk of stroke disclose low and high levels of APN and sCD40L, respectively, suggesting a role for APN if it favors platelet activation in vivo in this clinical setting. Enhancing APN levels may be a future goal to reduce the risk of vascular outcomes in AF patients.

Diabetes, Obesity and Atrial Fibrillation: Epidemiology, Mechanisms and Interventions

Body mass index (BMI) is a powerful predictor of death, type 2 diabetes (T2DM) and cardiovascular (CV) morbidity and mortality. Over the last few decades, we have witnessed a global rise in adult obesity of epidemic proportions. Similarly, there has been a parallel increase in the incidence of atrial fibrillation (AF), itself a significant cause of cardiovascular morbidity and mortality. This may be partly attributable to advances in the treatment of coronary heart disease (CHD) and heart failure (HF) improving life expectancy, however, epidemiological studies have demonstrated an independent association between obesity, diabetes and AF, suggesting possible common pathophysiological mechanisms and risk factors. Indeed, cardiac remodeling, haemodynamic alterations, autonomic dysfunction, and diastolic dysfunction have been reported in obese and diabetic cohorts. Moreover, diabetic cardiomyopathy is characterized by an adverse structural and functional cardiac phenotype, which may predispose to the development of AF. In this review, we discuss the pathophysiological and mechanistic relationships between obesity, diabetes and AF, and some of the challenges posed in the management of this high-risk group of individuals.

Obesity, diabetes and atrial fibrillation; epidemiology, mechanisms and interventions

The last few decades have witnessed a global rise in adult obesity of epidemic proportions. The potential impact of this is emphasized when one considers that body mass index (BMI) is a powerful predictor of death, type 2 diabetes (T2DM) and cardiovascular (CV) morbidity and mortality [1, 2]. Similarly we have witnessed a parallel rise in the incidence of atrial fibrillation (AF), the commonest sustained cardiac arrhythmia, which is also a significant cause of cardiovascular morbidity and mortality. Part of this increase is attributable to advances in the treatment of coronary heart disease (CHD) and heart failure (HF) improving life expectancy and consequently the prevalence of AF. However, epidemiological studies have demonstrated an independent association between obesity and AF, possibly reflecting common pathophysiology and risk factors for both conditions. Indeed, weight gain and obesity are associated with structural and functional changes of the cardiovascular system including left atrial and ventricular remodeling, haemodynamic alterations, autonomic dysfunction, and diastolic dysfunction. Moreover, diabetic cardiomyopathy is characterized by an adverse structural and functional cardiac phenotype which may predispose to the development of AF [3]. In this review, we discuss the pathophysiological and mechanistic relationships between obesity, diabetes and AF, and the challenges posed in the management of this high-risk group of individuals.

The prognostic role of the adiponectin levels in atrial fibrillation

BACKGROUND

Patients with atrial fibrillation (AF) have a high morbidity and mortality from vascular events, even despite oral anticoagulation (OAC). Rather than being a risk factor, AF has been proposed as a risk marker, being a signal of advanced atherosclerosis. Circulating adiponectin levels, a cytokine with anti-inflammatory and cardioprotector roles, are related to different atherosclerotic risk factors. The aim is to evaluate whether plasma adiponectin can be predictive of cardiovascular risk in anticoagulated patients with AF.

MATERIALS AND METHODS

We included 918 stable anticoagulated out patients with nonvalvular AF [50·1% male; median age 76 (70-80) years; median score for the stroke risk stratification scheme CHA(2) DS(2) -VASc was 4 (3-5)]. Plasma adiponectin was determined by ELISA. Clinical follow-up and cardiovascular adverse events were recorded.

RESULTS

After a median follow-up of 956 (784-1085) days, 113 cardiovascular events were recorded (annual rate 4·70%/year) and 99 patients died (rate 4·12%/year). Low plasma adiponectin (< 4444 ng/mL) was significantly associated with major cardiovascular events in female patients [HR 2·96 (95%CI 1·78-4·92)]; P < 0·001, even after adjusting for clinical confounder factors. Adiponectin was neither predictive of stroke/thromboembolism nor all-cause mortality in females, nor for any end-point in males.

CONCLUSIONS

Adiponectin is suggested as an independent prognostic biomarker for cardiovascular events in anticoagulated female patients with AF. Our data reinforce the importance of AF as a risk marker of atherosclerotic vascular damage.

Multiple biomarkers for the prediction of ischemic stroke: the PRIME study

OBJECTIVE

To simultaneously evaluate 14 biomarkers from distinct biological pathways for risk prediction of ischemic stroke, including biomarkers of hemostasis, inflammation, and endothelial activation as well as chemokines and adipocytokines.

METHODS AND RESULTS

The Prospective Epidemiological Study on Myocardial Infarction (PRIME) is a cohort of 9771 healthy men 50 to 59 years of age who were followed up over 10 years. In a nested case-control study, 95 ischemic stroke cases were matched with 190 controls. After multivariable adjustment for traditional risk factors, fibrinogen (odds ratio [OR], 1.53; 95% confidence interval [CI], 1.03-2.28), E-selectin (OR, 1.76; 95% CI, 1.06-2.93), interferon-γ-inducible-protein-10 (OR, 1.72; 95% CI, 1.06-2.78), resistin (OR, 2.86; 95% CI, 1.30-6.27), and total adiponectin (OR, 1.82; 95% CI, 1.04-3.19) were significantly associated with ischemic stroke. Adding E-selectin and resistin to a traditional risk factor model significantly increased the area under the receiver-operating characteristic curve from 0.679 (95% CI, 0.612-0.745) to 0.785 and 0.788, respectively, and yielded a categorical net reclassification improvement of 29.9% (P=0.001) and 28.4% (P=0.002), respectively. Their simultaneous inclusion in the traditional risk factor model increased the area under the receiver-operating characteristic curve to 0.824 (95% CI, 0.770-0.877) and resulted in an net reclassification improvement of 41.4% (P<0.001). Results were confirmed when using continuous net reclassification improvement.

CONCLUSIONS

Among multiple biomarkers from distinct biological pathways, E-selectin and resistin provided incremental and additive value to traditional risk factors in predicting ischemic stroke.

Hypoadiponectinemia in patients with paroxysmal atrial fibrillation

Background and Objectives

Adiponectin is an adipose tissue-derived hormone that has beneficial effects on cardiac function and has been reported to be associated with lipid metabolism, glucose metabolism, and insulin resistance. Serum levels of adiponectin are reduced in obese individuals compared with non-obese individuals. Obesity is associated with an increased incidence of atrial fibrillation (AF); however, the role of adiponectin in AF is unclear. The aim of this study is to evaluate the relationship between the plasma adiponectin level and AF.

Subjects and Methods

Sixty-one consecutive patients were prospectively enrolled for this study. Subjects were divided into two groups: patients with AF (n=30) and controls (n=31). Laboratory evaluation, including levels of plasma adiponectin, was performed and echocardiographic parameters were measured.

Results

The baseline characteristics were not different between the two groups. The plasma adiponectin level of patients in the AF group was significantly lower than in the control group (14.9±7.2 vs. 19.±8.9 µg/mL, p<0.05). In addition, when we divided the AF patients into paroxysmal and chronic AF, the plasma adiponectin level was significantly lower in patients with paroxysmal AF, compared with the control group. In multiple binary logistic regression analysis to evaluate the independent predictors for AF, adiponectin and left atrial diameter were strong independent predictors of AF.

Conclusion

In this study a lower plasma adiponectin concentration was significantly associated with that of paroxysmal AF. Hypoadiponectinemia can potentially be an important risk factor for AF.

Atrial Fibrillation Ablation in Obese Patients

Despite the increased burden of atrial fibrillation (AF), obese patients have similar, if not slightly improved, mortality, described as the "obesity paradox." Catheter ablation for AF in obese patients is a reasonable option, but patients should be screened for sleep apnea and counseled about the possibility of longer procedure times and repeat procedures to achieve similar success rates. Quality of life will likely improve after successful ablation. Although no statistically significant increases in procedural complications have occurred in obese subjects, patients should be counseled about the increased radiation dose and higher incidence of left atrial thrombus preablation.

Plasma resistin, adiponectin, and risk of incident atrial fibrillation: the Framingham Offspring Study

BACKGROUND

We sought to investigate whether higher concentrations of resistin and lower concentrations of adiponectin relate to incident atrial fibrillation (AF) and whether this association is mediated by AF risk factors and inflammation. Resistin and adiponectin are adipokines that have been associated with multiple known risk factors for AF including diabetes, obesity, inflammation, and heart failure.

METHODS

We studied the relations between circulating concentrations of both adipokines and incident AF in participants of the Framingham Offspring Study.

RESULTS

Participants (n = 2,487) had a mean age of 61 ± 10 years, and 54% were women. During a mean follow-up of 7.6 ± 2.0 years, 206 (8.3%) individuals (96 women) developed incident AF. Plasma resistin concentration was significantly associated with incident AF (multivariable-adjusted hazard ratio [HR] 1.17 per SD [0.41 ng/mL] of natural logarithmically transformed resistin, 95% CI 1.02-1.34, P = .028). The resistin-AF association was attenuated after further adjustment for C-reactive protein (HR per SD increase resistin 1.14, 95% CI 0.99-1.31, P = .073). Adiponectin concentrations were not significantly associated with incident AF (multivariable-adjusted HR of 0.95 per SD [0.62 μg/mL] of logarithmically transformed adiponectin, 95% CI 0.81-1.10, P = .478).

CONCLUSION

In our community-based longitudinal study, higher mean concentrations of resistin were associated with incident AF, but the relation was attenuated by adjustment for C-reactive protein. We did not detect a statistically significant association between adiponectin and incident AF. Additional studies are needed to clarify the potential role of adipokines in AF and mechanisms linking adiposity to AF.

Blood biomarkers in cardioembolic stroke

One promising field in neurovascular diseases investigation is the use of biomarkers to guide stroke etiology diagnosis and classification. Since treatment differs among etiologic subtypes and nowadays many patients receive a diagnosis of undetermined stroke, biomarkers might become an important additional diagnostic tool. In this review we update current knowledge about biomarkers related with cardioembolic stroke etiology (such as BNP and D-dimer proteins, or PITX2 and ZFHX3 genes), that in the future, might allow rapidly guiding other diagnostic tests and accelerating the onset of an optimal secondary prevention.

Effect of adiponectin overexpression on stability of preexisting plaques by inducing prolyl-4-hydroxylase expression

BACKGROUND

Although adiponectin has been implicated as an antiinflammatory factor in atherosclerotic lesion development, little is known about its role in advanced atherosclerotic plaque. This study assessed the effect and mechanism of adiponectin on the expression of prolyl 4-hydroxylase (P4H) alpha1 and its role in the stability of preexisting plaque.

METHODS AND RESULTS

Atherosclerotic lesions in the carotid arteries of apolipoprotein E-deficient mice were induced by the placement of a perivascular collar. Six weeks after surgery, 120 mice were divided into phosphate-buffered saline (PBS) (n=40), empty adenovirus (Ad.Empty) (n=40) and adiponectin adenovirus (Ad.Adipo) groups (n=40). The number of vulnerable lesions were lower with Ad.Adipo than with Ad.Empty transfection. Mean cap thickness, cap area, cap-to-core ratio and intimal collagen content were all greater with Ad.Adipo than with Ad.Empty transfection; however, the groups did not differ in plaque area or intima-media thickness. Plasma adiponectin level positively correlated with intimal collagen content. Adiponectin transfection conferred enhanced expression of P4H, with no changes in the PBS and Ad.Empty groups.

CONCLUSIONS

Adiponectin increases collagen production by inducing the expression of P4H, which may play a major role in the development of the thick fibrous cap of advanced atherosclerotic plaque.

Biomarkers of extracellular matrix turnover

The extracellular cardiac matrix (ECCM) plays an important role in the support of myocytes and fibroblasts. ECCM turnover is influenced by ischemia, stretch, inflammation, and neurohormonal mediators. Myocardial fibrosis is the consequence of several pathologic processes mediated by mechanical, neurohormonal, and cytokine factors. It is a major determinant of diastolic dysfunction and pumping capacity and may result in tissue heterogeneity, dys-synchrony, and arrhythmias. The measurement of various serum peptides arising from the metabolism of collagen types 1 and 3, of degradation fragments, and of specific metalloproteinases may provide noninvasive assessment of fibrosis. ECCM biomarkers are clinically useful tools, particularly given the potential for cardioprotective and cardioreparative pharmacologic strategies.

Atrial function during different multisite atrial pacing modalities in patients with bradycardia--tachycardia syndrome

BACKGROUND

Multisite atrial pacing (MAP) was introduced to improve atrial electrical synchrony and prevent recurrence of atrial fibrillation (AF).

METHODS AND RESULTS

In the present study there were 57 patients with sinus node disease, AF recurrence and prolonged P-wave on ECG with 2 MAP modalities. In all patients 1 lead was implanted in the coronary sinus (CS) ostium area. In the right atrial appendage (RAA)+CS group (28 patients) the other atrial lead was in the RAA, and in the BB+CS group (29 patients) in the Bachmann's bundle (BB) region. Tissue Doppler was used to register the electromechanical delay (EMD) in the atrial walls and estimate the atrial contraction synchrony. Cardiac output and myocardial performance index did not differ during the 2 MAP modalities. During BB+CS, in comparison with RAA+CS pacing, the peak of the mitral atrial wave occurred earlier (P<0.01), the usual right-left atrial contraction sequence was reversed more frequently (P<0.004), all atrial EMDs except for the lateral left atrium (LA) were shorter (P<0.05), and LA synchrony was greater (P<0.001).

CONCLUSIONS

In patients treated with MAP, implanting 1 of the atrial leads in the BB area instead of the RAA has no influence on global cardiac hemodynamics, but does result in earlier LA contraction, and reversal of the typical right-left atrial contraction sequence, as well as providing greater LA contraction synchrony.

Relationship between adiponectin and left atrium size in uncomplicated obese patients: adiponectin, a link between fat and heart

BACKGROUND

It is well known that obesity is a risk factor for severe cardiovascular complications, such as coronary heart disease, heart failure, stroke, venous thromboembolic disease, and atrial fibrillation. Left ventricle (LV) and left atrium (LA) enlargement is a characteristic feature of these patients with the consequent cardiovascular risk. Factors other than hemodynamic may influence LA remodeling. The aim of the study is to evaluate the relationship between adiponectin and LA size in uncomplicated obese patients.

METHODS

Seventy-four asymptomatic obese patients and an age- and sex-matched control group (N = 70) were recruited. A detailed clinical, echocardiographic, and analytical study was performed. Insulin resistance was assessed using the homeostasis model assessment for insulin resistance (HOMA-IR) method. Insulin sensitivity was assessed measuring serum total adiponectin concentrations.

RESULTS

Adiponectin levels were lower in the obese group (P < 0.001) and particularly so in those obese participants with enlarged LA (32%; P < 0.0005). LA sizes were higher in the obese group (P < 0.0005). Adiponectin displayed significant correlations with body mass index, glucose, insulin, high-density lipoprotein cholesterol, and triglyceride concentrations as well as HOMA-IR (P < 0.001 for all). Adiponectin displayed significant correlations with LV mass and LA size, diastolic and systolic cardiac volumes and diameters, and cardiac output (P < 0.001 for all). Adiponectin correlations with LA size (r = -0.429; P < 0.001) persisted after adjustment for HOMA-IR, age, sex, and LV mass.

CONCLUSIONS

A novel inverse relationship between adiponectin and LA size independent of age, sex, insulin resistance, and LV mass appears in our series. Adiponectin could be a link between adipose tissue and the heart, having an influence on cardiac remodeling.