Circulating cardiovascular biomarkers in recurrent atrial fibrillation: data from the GISSI-atrial fibrillation trial

No Detectable Differences in microRNA Plasma Levels between Diabetic Hypertensive Patients with and without Incident Subclinical Atrial Fibrillation

Background: Long-term rhythm monitoring (LTRM) can detect undiagnosed atrial fibrillation (AF) in patients at risk of AF and stroke. Circulating microRNAs (miRNAs), which have been shown to play a role in atrial electrical and structural remodelling, could help to select patients who would benefit most from LTRM. The aim of this study was to investigate whether patients with diabetes mellitus (DM) and hypertension and screen-detected subclinical AF (SCAF) using an insertable cardiac monitor (ICM) have significantly different plasma baseline levels of five selected miRNAs playing a role in the modulation of atrial electrical and structural remodelling (miR-21-5p, miR-29b-3p, miR-150-5p, miR-328-3p, and miR-432-5p) compared to those without SCAF. Methods: This study was performed at the outpatient clinic of a secondary academic teaching hospital between December 2013 and November 2015. Eligible patients were ≥65 years of age with DM and hypertension but without known heart diseases. All patients received an ICM. On the day of ICM implantation, blood samples for the measurement of plasma levels of the five miRNAs were drawn. In this post hoc analysis, we investigated their expression by reverse transcription-quantitative polymerase chain reaction. MiRNA plasma levels in patients with and without newly detected SCAF were compared. Results: We included 82 consecutive patients (median age of 71.3 years (IQR 67.4-75.1)), who were followed for a median of 588 days (IQR: 453-712 days). Seventeen patients (20.7%) had ICM-detected SCAF. Plasma levels of miR-328-3p, miR-29b-3p, miR-21-5p, miR-432-5p, and miR-150-5p were slightly but not significantly different in patients with incident SCAF compared with patients without. Conclusions: In patients with hypertension and DM, newly detected SCAF was not significantly associated with changes in expression levels of miR-21-5p, miR-29b-3p, miR-150-5p, miR-328-3p, and miR-432-5p.

Atrial Natriuretic Peptides as a Bridge between Atrial Fibrillation, Heart Failure, and Amyloidosis of the Atria

ANP is mainly synthesized by the atria, and upon excretion, it serves two primary purposes: vasodilation and increasing the renal excretion of sodium and water. The understanding of ANP's role in cardiac systems has improved considerably in recent decades. This review focuses on several studies demonstrating the importance of analyzing the regulations between the endocrine and mechanical function of the heart and emphasizes the effect of ANP, as the primary hormone of the atria, on atrial fibrillation (AF) and related diseases. The review first discusses the available data on the diagnostic and therapeutic applications of ANP and then explains effect of ANP on heart failure (HF) and atrial fibrillation (AF) and vice versa, where tracking ANP levels could lead to understanding the pathophysiological mechanisms operating in these diseases. Second, it focuses on conventional treatments for AF, such as cardioversion and catheter ablation, and their effects on cardiac endocrine and mechanical function. Finally, it provides a point of view about the delayed recovery of cardiac mechanical and endocrine function after cardioversion, which can contribute to the occurrence of acute heart failure, and the potential impact of restoration of the sinus rhythm by extensive ablation or surgery in losing ANP-producing sites. Overall, ANP plays a key role in heart failure through its effects on vasodilation and natriuresis, leading to a decrease in the activity of the renin-angiotensin-aldosterone system, but it is crucial to understand the intimate role of ANP in HF and AF to improve their diagnosis and personalizing the patients' treatment.

Effects of Adrenomedullin on Atrial Electrophysiology and Pulmonary Vein Arrhythmogenesis

Adrenomedullin, a peptide with vasodilatory, natriuretic, and diuretic effects, may be a novel agent for treating heart failure. Heart failure is associated with an increased risk of atrial fibrillation (AF), but the effects of adrenomedullin on atrial arrhythmogenesis remain unclear. This study investigated whether adrenomedullin modulates the electrophysiology of the atria (AF substrate) or pulmonary vein (PV; AF trigger) arrhythmogenesis. Conventional microelectrode or whole-cell patch clamps were used to study the effects of adrenomedullin (10, 30, and 100 pg/mL) on the electrical activity, mechanical response, and ionic currents of isolated rabbit PV and sinoatrial node tissue preparations and single PV cardiomyocytes. At 30 and 100 pg/mL, adrenomedullin significantly reduced the spontaneous beating rate of the PVs from 2.0 ± 0.4 to 1.3 ± 0.5 and 1.1 ± 0.5 Hz (reductions of 32.9% ± 7.1% and 44.9 ± 8.4%), respectively, and reduced PV diastolic tension by 12.8% ± 4.1% and 14.5% ± 4.1%, respectively. By contrast, adrenomedullin did not affect sinoatrial node beating. In the presence of L-NAME (a nitric oxide synthesis inhibitor, 100 μM), adrenomedullin (30 pg/mL) did not affect the spontaneous beating rate or diastolic tension of the PVs. In the single-cell experiments, adrenomedullin (30 pg/mL) significantly reduced the L-type calcium current (I_Ca-L) and reverse-mode current of the sodium-calcium exchanger (NCX). Adrenomedullin reduces spontaneous PV activity and PV diastolic tension by reducing I_Ca-L and NCX current and thus may be useful for treating atrial tachyarrhythmia.

Total NT-proBNP, a novel biomarker related to recurrent atrial fibrillation

Background

Novel circulating biomarkers may help in understanding the underlying mechanisms of atrial fibrillation (AF), a challenge for AF management and prevention of cardiovascular (CV) events. Whether glycosylation affects the prognostic value of N-terminal pro-B type natriuretic peptide (NT-proBNP) in AF is still unknown.

Objectives

To test how deglycosylated total NT-proBNP, NT-proBNP and a panel of biomarkers are associated with: (1) recurrent AF, (2) first hospitalization for CV reasons.

Methods

A total of 382 patients of the GISSI-AF trial in sinus rhythm with a history of AF, echocardiographic variables, total NT-proBNP, NT-proBNP and nine additional biomarkers [Total N-terminal pro-B type natriuretic peptide (Total NT proBNP), N-terminal pro-B type natriuretic peptide (NTproBNP), Angiopoietin 2 (Ang2), Bone morphogenic protein-10 (BMP10), Dickkopf-related protein-3 (DKK3), Endothelial cell specific molecule-1 (ESM1), Fatty acid-binding protein 3 (FABP3), Fibroblast growth factor 23 (FGF23), Growth differentiation factor-15 (GDF15), Insulin-like growth factor-binding protein-7 (IGFBP7) and Myosin binding protein C3 (MYPBC3)]. were assayed at baseline, 6 and 12 months under blind conditions in a laboratory at Roche Diagnostics, Penzberg, Germany. The associations between circulating biomarkers and AF at the 6- and 12-month visits, and their predictive value, were assessed in multivariable models with logistic regression analysis and Cox proportional hazards regression analysis. Biomarkers associations were modelled for 1SD increase in their level.

Results

Over a median follow-up of 365 days, 203/382 patients (53.1%) had at least one recurrence of AF and 16.3% were hospitalized for CV reasons. Total NT-proBNP, NT-proBNP, Ang2 and BMP10 showed the strongest associations with ongoing AF. Natriuretic peptides also predicted recurrent AF (total NT-proBNP: HR:1.19[1.04–1.36], p = 0.026; NT-proBNP: HR:1.19[1.06–1.35], p = 0.016; Ang2: HR:1.07[0.95–1.20], p = 0.283; BMP10: HR:1.09[0.96–1.25], p = 0.249) and CV hospitalization (total NT-proBNP: HR:1.57[1.29–1.90], p < 0.001 1.63], p = 0.097).

Conclusions

The association of total NT-proBNP with the risk of AF first recurrence was similar to that of NT-proBNP, suggesting no influence of glycosylation. Analogous results were obtained for the risk of first hospitalization for CV reasons. Natriuretic peptides, Ang2 and BMP10 were associated with ongoing AF. Findings from the last two biomarkers point to a pathogenic role of cardiac extracellular matrix and cardiomyocyte growth in the myocardium of the right atrium and ventricle.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02358-y.

Circulating biomarkers, echocardiographic parameters, and incident subclinical atrial fibrillation in patients with diabetes and hypertension

BACKGROUND

Long-term rhythm monitoring (LTRM) can detect undiagnosed atrial fibrillation (AF) in patients at high risk of AF and stroke. Biomarkers and echocardiographic parameters could, however, help identify patients benefitting most from LTRM. The aim of this study was to investigate, whether circulating biomarkers of cardiac and vascular function (brain natriuretic peptide (BNP), cardiac troponin I (cTnI), copeptin, and mid-regional proadrenomedullin (MR-proADM)) and echocardiographic parameters were associated with incident subclinical AF (SCAF) in a population at high risk of stroke in the presence of AF. For this purpose, we investigated individuals ≥65 years of age with hypertension and diabetes mellitus, but no history or symptoms of AF or other cardiovascular disease (CVD).

METHODS

We included 82 consecutive patients (median age 71.3 years (IQR 67.4-75.1)). All patients received an insertable cardiac monitor (ICM) and were followed for a median of 588 days (IQR 453-712). On the day of ICM implantation, a comprehensive echocardiogram and blood samples were obtained.

RESULTS

During a median follow-up of 588 days (IQR: 453-712 days), incident SCAF occurred in 17 patients (20.7%) with a median time to first-detected episode of 91 days (IQR 41-251 days). MR-proADM (median 0.87 nmol/L (IQR 0.76-1.02) vs 0.78 nmol/L (IQR 0.68-0.98)) and copeptin (median 13 pmol/L (IQR 9-17) vs 8 pmol/L (IQR 4-18)) levels were insignificantly higher in patients with incident SCAF. BNP and cTnI concentrations and echocardiographic parameters were similar in the two groups.

CONCLUSIONS

MR-proADM, BNP, cTnI, copeptin, and several echocardiographic parameters were not associated with incident SCAF in this cohort of patients with hypertension and diabetes, but without any underlying CVD.

Atrial fibrillation: is there a role for cardiac troponin?

Atrial fibrillation (AF) is the most common sustained arrhythmia, and its prevalence rate is expected to be doubled over the next decades. Despite the wide use of biomarkers in the management of different cardiac diseases such as myocardial infarction and heart failure, utilization of biomarkers in AF management is not routinely recommended by current guidelines. There is also growing evidence that higher levels of cardiac-specific troponin, as an intracellular protein involved in cardiomyocyte contraction, may be associated with the risk of incident and recurrent AF and its complications. In the present paper, we review the association between troponin and AF and propose clinical suggestions for use of troponin in the management of AF patients.

Decreased plasma musclin levels are associated with potential atrial fibrillation in non-diabetic patients

Background

Musclin is involved in the regulation of natriuretic peptide (NP) clearance and may affect the concentration of atrial natriuretic peptide (ANP). It has also been found to play an important role in several diseases, such as diabetes mellitus and hypertension. Both abnormalities in ANP and associated medical history are involved in the pathogenesis of atrial fibrillation (AF). However, plasma concentration of musclin as a biomarker for risk stratification in patients with AF has not been fully investigated.

Methods

Plasma musclin levels were measured in 290 patients with AF (including 199 paroxysmal AF patients and 91 persistent AF patients) and 120 control subjects. The association between plasma musclin levels and AF onset, as well as its predictive effects on clinical outcomes after cryoballoon ablation were analyzed.

Results

AF patients were found to have a lower concentration of plasma musclin than healthy controls. Moreover, in the non-diabetic group and normal N-terminal pro-brain natriuretic peptide (NT-proBNP) level group, the association between lower plasma concentration of musclin and AF remained significant. According to receiver operating characteristic (ROC) curve analysis, the optimal cut-off point of musclin for predicting AF onset was 54.94 ng/mL, which had a sensitivity of 81.67% and a specificity of 31.47% [area under the ROC curve (AUC) =60.71%]. In follow-up studies, both diabetes and left atrial size were independent predictors of AF recurrence after ablation, while musclin showed only a modest relationship with the outcome of cryoballoon ablation.

Conclusions

Our data indicated that decreased musclin was associated with the onset of AF. Moreover, lower plasma levels of musclin were an independent risk factor of AF in non-diabetic patients. Our studies suggest that musclin could be a predictive factor for the onset of AF.

Usefulness of High-Sensitivity Troponin I to Predict Outcome in Patients With Newly Detected Atrial Fibrillation

The prognostic role of high-sensitivity cardiac troponin I (hs-TnI) in patients with newly detected atrial fibrillation (AF) is not well established. We investigate the association of elevated hs-TnI with clinical outcomes and explore the utility of hs-TnI for risk assessment in patients with newly detected AF. From August 2014 to December 2016, 2,361 consecutive patients with newly detected AF were enrolled in a retrospective, single-center registry. Of these, 957 patients were selected and classified into 4 groups according to hs-TnI quartiles. The primary outcome was all-cause death during follow-up. The hs-TnI level was 3.6 ng/L or less in the lowest quartile (Q1), more than 3.6 ng/L to 10.1 ng/L or less in the second quartile (Q2), more than 10.1 ng/L to 22.0 ng/L or less in the third quartile (Q3), and more than 22.0 ng/L in the highest quartile (Q4). The median follow-up period was 19.3 months. In multivariable Cox regression model, Q4 has a higher risk of all-cause death (adjusted hazard ratio [HR]: 3.49; 95% confidence interval [CI]: 1.21 to 10.00; p = 0.02), readmission for heart failure (adjusted HR: 1.75; 95% CI: 1.01-3.05; p = 0.04), and readmission for revascularization (adjusted HR: 3.90; 95% CI: 1.25 to 12.17; p = 0.02) compared with Q1. Independent predictors of all-cause death were renal insufficiency (adjusted HR: 1.96; 95% CI: 1.08 to 3.53; p = 0.02), highest hs-TnI quartile (adjusted HR: 3.30; 95% CI: 1.18 to 9.27; p = 0.02) and anticoagulation therapy (adjusted HR: 0.51; 95% CI: 0.27 to 0.93; p = 0.03). Elevated hs-TnI is independently associated with higher mortality in patients with AF and serves as a valuable prognostic biomarker in patients with newly detected AF.

Relationship between hemoglobin A1c and serum troponin in patients with diabetes and cardiovascular events

Objectives

Diabetes mellitus is a group of metabolic disorders associated with high risk for cardiovascular disease. Although troponins are primarily clinically used for the diagnosis of acute coronary syndrome, they are also used in risk assessment in patients with acute coronary syndrome as well as in a number of other conditions. The aim of this review was to investigate the relationship between hemoglobin A1c and serum troponin in patients with diabetes and cardiovascular events.

Methods

Hemoglobin A1_c has been chosen as the best clinical indicator of glucose control and risk of micro and macrovascular complications. We investigated cardiac troponins as a group of markers of muscle injury which includes troponin T, troponin I and troponin C. Troponin T and I are specific for myocardial injury, compared to C which is specific for skeletal muscle.

Results

In this review, we showed that there was a causal relation between hemoglobin A1_c levels and serum troponin concentrations. Hemoglobin A1_c has shown to be a positive predictive factor of incidence, mortality and morbidity of conditions such as acute coronary syndrome, arrhythmias, stroke, pulmonary embolism and other conditions that causes troponin elevation by its release in circulation.

Conclusions

Chronic hyperglycemia decreases glomerular filtration and consequently decreases troponin elimination and also by affecting the heart microcirculation it leads to microvascular damage and consequently to ischemia which contribute to troponin concentration elevation. Furthermore, correlation between hemoglobin A1_c and troponin concentration manifests in their prognostic value for mortality.

The Impact of Repeated Cardioversions for Atrial Fibrillation on Stroke, Hospitalizations, and Catheter Ablation Outcomes

BACKGROUND

Long-term outcomes after direct current cardioversion (DCCV) in patients that receive anticoagulation have demonstrated to have no adverse sequela. Less is known about the impact on atrial fibrillation (AF) outcomes and resource utilization of repeated DCCVs that are often required for long-term rhythm control.

METHODS

A total of 4,135 AF patients >18 years of age that underwent DCCV with long-term system follow-up were evaluated. Patients were stratified by the number of DCCVs received: 1 (n=2,201), 2-4 (n=1,748), and ≥5 (n=186). Multivariable Cox hazard regression was used to determine the association of DCCV categories to the outcomes of death, AF hospitalization, AF ablation, DCCVs, and stroke/transient ischemic attack.

RESULTS

The average follow-up of the patient population was 1,633.1±1,232.9 (median: 1,438.0) days. Patients who underwent 2-4 and ≥5 DCCVs had more comorbidities, namely hypertension, hyperlipidemia and heart failure. Anticoagulation use was common at the time of DCCV in all groups (89.1%, 91.2%, 91.9%, p=0.06) and amiodarone use increased with increasing DCCV category (30.1%, 43.4%, 52.2, p<0.0001). At 5 years, patients that received more DCCVs had higher rates of repeat DCCVs, AF hospitalizations, and ablations. Stroke rates were not increased. Though not statistically significant, 5-year death was increased when comparing DCCV >5 vs. 1, (HR=1.32 [0.89-1.94], p=0.17).

CONCLUSIONS

This study found that the increasing number of DCCVs, despite escalation of other pharmacologic and nonpharmacologic therapies, is a long-term independent risk factor for repeat DCCVs, ablations, and AF hospitalizations among AF patients.

Natriuretic Peptides in Heart Failure with Preserved Left Ventricular Ejection Fraction: From Molecular Evidences to Clinical Implications

The incidence of heart failure with preserved ejection fraction (HFpEF) is increasing and its challenging diagnosis and management combines clinical, imagistic and biological data. Natriuretic peptides (NPs) are hormones secreted in response to myocardial stretch that, by increasing cyclic guanosine monophosphate (cGMP), counteract myocardial fibrosis and hypertrophy, increase natriuresis and determine vasodilatation. While their role in HFpEF is controversial, most authors focused on b-type natriuretic peptides (BNPs) and agreed that patients may show lower levels. In this setting, newer molecules with an increased specificity, such as middle-region pro-atrial natriuretic peptide (MR-proANP), emerged as promising markers. Augmenting NP levels, either by NP analogs or breakdown inhibition, could offer a new therapeutic target in HFpEF (already approved in their reduced EF counterparts) by increasing the deficient cGMP levels found in patients. Importantly, these peptides also retain their prognostic value. This narrative review focuses on NPs’ physiology, diagnosis, therapeutic and prognostic implication in HFpEF.

Biomarkers of Atrial Fibrillation in Hypertension

Background:

Atrial fibrillation (AF) is the most frequently encountered cardiac arrhythmia globally and substantially increases the risk for thromboembolic disease. Albeit, 20% of all cases of AF remain undiagnosed. On the other hand, hypertension amplifies the risk for both AF occurrences through hemodynamic and non-hemodynamic mechanisms and cerebrovascular ischemia. Under this prism, prompt diagnosis of undetected AF in hypertensive patients is of pivotal importance.

Method:

We conducted a review of the literature for studies with biomarkers that could be used in AF diagnosis as well as in predicting the transition of paroxysmal AF to sustained AF, especially in hypertensive patients.

Results:

Potential biomarkers for AF can be broadly categorized into electrophysiological, morphological and molecular markers that reflect the underlying mechanisms of adverse atrial remodeling. We focused on P-wave duration and dispersion as electrophysiological markers, and left atrial (LA) and LA appendage size, atrial fibrosis, left ventricular hypertrophy and aortic stiffness as structural biomarkers, respectively. The heterogeneous group of molecular biomarkers of AF encompasses products of the neurohormonal cascade, including NT-pro BNP, BNP, MR-pro ANP, polymorphisms of the ACE and convertases such as corin and furin. In addition, soluble biomarkers of inflammation (i.e. CRP, IL-6) and fibrosis (i.e. TGF-1 and matrix metalloproteinases) were assessed for predicting AF.

Conclusion:

The reviewed individual biomarkers might be a valuable addition to current diagnostic tools but the ideal candidate is expected to combine multiple indices of atrial remodeling in order to effectively detect both AF and adverse characteristics of high risk patients with hypertension.

Prediction and Management of Recurrences after Catheter Ablation in Atrial Fibrillation and Heart Failure

Catheter ablation is recommended in patients with symptomatic atrial fibrillation (AF) refractory to pharmacologic therapy. AF recurrence is common postablation, particularly in patients with heart failure, because of multiple structural and functional changes that can occur. Determining predictors of AF recurrence has become increasingly important. These include increased left atrial volume, termination of AF during the index ablation, electrocardiogram parameters, and serum biomarkers. Cardiac MRI can also determine the degree of scarring and left atrial sphericity, which is used in risk prediction scores. In patients with recurrence, further treatment options include pharmacologic therapy and atrioventricular nodal ablation with pacing.

Plasma endothelin-1 levels are increased in atrial fibrillation patients with hyperthyroidism

BACKGROUND

Endothelin-1 (ET-1) is a potent vasoconstrictor, mitogen and inflammatory factor that may contribute to development of atrial fibrillation (AF). Plasma ET-1 levels are increased in hyperthyroid patients, but studies evaluating its relation to AF development in hyperthyroid patients are lacking.

OBJECTIVE

The present study seeks to evaluate the relation of plasma ET-1 to AF development as a function of thyroid status.

METHODS

Blood samples from euthyroid patients (n = 41), hypothyroid (n = 61), hyperthyroid (n = 41), AF with hyperthyroidism (n = 9), and euthyroid AF (n = 10) patients were collected. Plasma ET-1, CRP, and thyroid hormone levels were measured and compared between groups.

RESULTS

Plasma ET-1 levels were higher in hyperthyroid and euthyroid AF patients> hyperthyroid-non-AF > hypo and euthyroid non-AF patients. Plasma ET-1 levels positively correlated with free T3 and T4 levels, and negatively with TSH levels. By multivariate analysis, plasma ET-1 was positively associated with AF, hyperthyroidism, and age. Plasma CRP did not vary by study group in either univariate or multivariate analyses.

CONCLUSION

Plasma ET-1 is associated with AF, elevated in hyperthyroid patients and positively correlated with thyroid hormone levels, suggesting that hyperthyroidism may increase ET-1 expression and release. This study may guide development of novel predictors of AF associated with hyperthyroidism, and may help to personalize therapy in hyperthyroid patients.

Connexins and Atrial Fibrillation in Obstructive Sleep Apnea

PURPOSE OF THE REVIEW

To summarize the potential interactions between obstructive sleep apnea (OSA), atrial fibrillation (AF), and connexins.

RECENT FINDINGS

OSA is highly prevalent in patients with cardiovascular disease, and is associated with increased risk for end-organ substantial morbidities linked to autonomic nervous system imbalance, increased oxidative stress and inflammation, ultimately leading to reduced life expectancy. Epidemiological studies indicate that OSA is associated with increased incidence and progression of coronary heart disease, heart failure, stroke, as well as arrhythmias, particularly AF. Conversely, AF is very common among subjects referred for suspected OSA, and the prevalence of AF increases with OSA severity. The interrelationships between AF and OSA along with the well-known epidemiological links between these two conditions and obesity may reflect shared pathophysiological pathways, which may depend on the intercellular diffusion of signaling molecules into either the extracellular space or require cell-to-cell contact. Connexin signaling is accomplished via direct exchanges of cytosolic molecules between adjacent cells at gap membrane junctions for cell-to-cell coupling. The role of connexins in AF is now quite well established, but the impact of OSA on cardiac connexins has only recently begun to be investigated. Understanding the biology and regulatory mechanisms of connexins in OSA at the transcriptional, translational, and post-translational levels will undoubtedly require major efforts to decipher the breadth and complexity of connexin functions in OSA-induced AF.

SUMMARY

The risk of end-organ morbidities has initiated the search for circulating mechanistic biomarker signatures and the implementation of biomarker-based algorithms for precision-based diagnosis and risk assessment. Here we summarize recent findings in OSA as they relate to AF risk, and also review potential mechanisms linking OSA, AF and connexins.

[Biomarkers and atrial fibrillation : Prediction of recurrences and thromboembolic events after rhythm control management]

Atrial fibrillation (AF) is the most common arrhythmia in clinical praxis and is associated with an increased risk for cardio- and cerebrovascular complications leading to an increased mortality. Catheter ablation represents one of the most important and efficient therapy strategies in AF patients. Nevertheless, the high incidence of arrhythmia recurrences after catheter ablation leads to repeated procedures and higher treatment costs. Recently, several scores had been developed to predict rhythm outcomes after catheter ablation. Biomarker research is also of enormous interest. There are many clinical and blood biomarkers pathophysiologically associated with AF occurrence, progression and recurrences. These biomarkers-including different markers in blood (e. g. von Willebrand factor, D‑dimer, natriuretic peptides) or urine (proteins, epidermal grown factor receptor) but also cardiac imaging (echocardiography, computed tomography, magnetic resonance imaging)-could help to improve clinical scores and be useful for individualized AF management and optimized patients' selection for different AF treatment strategies. In this review, the role of diverse biomarkers and their predictive value related to AF-associated complications are discussed.

Effects of hyperoxia on myocardial injury following cardioversion-A randomized clinical trial

Oxygen has long been assumed beneficial for all ill and injured patients. However, hyperoxia may be harmful and aggravate myocardial injury such as that caused by myocardial infarction. We aimed to investigate if hyperoxia increases myocardial injury following direct current cardioversion compared with room air.

METHODS

Patients undergoing elective biphasic cardioversion for atrial fibrillation or atrial flutter were randomized to receive room air or oxygen (10-15 L/min) during the procedure. The primary endpoint was the difference in high-sensitive Troponin I (hs-cTnI) and -T (hs-cTnT) measured 2 hours before and 4 hours after cardioversion. Secondary endpoints were differences in Copeptin and NT-pro-BNP.

RESULTS

A total of 65 patients were randomized to high-flow oxygen (male: 71%, mean age 66.9 years) and 59 patients to room air (male: 80%, mean age 65.5 years). There was no difference in hs-cTnI between patients treated with oxygen compared to patients treated with room air (P=.09) and no significant difference for hs-cTnT, ratio 1.08 (95% CI: 0.99-1.18) (P=.09). Median hs-cTnI difference before and after cardioversion was 0.1 (interquartile range (IQR): -0.5 to 0.5) ng/L for the high-flow oxygen group and -0.3 (IQR: -1.1 to 0.4) ng/L for the room air group. There was no difference in Copeptin between patients treated with oxygen compared to room air (ratio 1.06 (95% CI: 0.89-1.27) (P=.51) or NT-pro-BNP (difference-6.0 ng/L (95% CI: -78.5 to 66.6) P=.87).

CONCLUSION

Direct current cardioversion of atrial fibrillation/flutter with and without high-flow oxygen supplement was not associated with myocardial injury evaluated by high sensitive myocardial biomarkers.

Natriuretic Propeptides as Markers of Atrial Fibrillation Burden and Recurrence (from the AMIO-CAT Trial)

Natriuretic peptides are established plasma markers of systolic heart failure, but their usefulness for the evaluation of atrial fibrillation (AF) is unknown. We examined mid-regional pro-atrial natriuretic peptide (MR-proANP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients undergoing ablation for AF. A subpopulation of 102 patients (median age 60 [52;65], 82% male) from the AMIO-CAT trial (Recurrence of arrhythmia following short-term oral AMIOdarone after CATheter ablation for atrial fibrillation: a double-blind, randomized, placebo-controlled study) undergoing ablation for paroxysmal (n = 55) or persistent (n = 47) AF was studied. MR-proANP and NT-proBNP were measured before ablation and at 1, 3, and 6 months' follow-up. Three-day Holter monitoring was performed before ablation, and 6 to 8 weeks and 6 months after ablation. Plasma MR-proANP and NT-proBNP concentrations were higher during AF than during sinus rhythm before ablation (188 pmol/L [131;260] vs 94 pmol/L [64;125], p <0.001; 78 pmol/L [43;121] vs 10.3 pmol/L [5.9;121], p <0.001) and at 1, 3, and 6 months' follow-up. Categories of AF burden on 3-day Holter monitoring (0%, 0% to 99%, and 99% to 100%) were associated with plasma concentrations of both MR-proANP (94 pmol/L [55;127] vs 117 pmol/L [88;185] vs 192 pmol/L [127;261], p <0.001) and NT-proBNP (10 pmol/L [5.9;22] vs 22 pmol/L [8.9;53] vs 81 pmol/L [45;116], p <0.001). In a multivariate regression analysis, however, there was no significant association between baseline propeptide concentrations and recurrence of AF at 6 months' follow-up. In conclusion, AF was associated with higher plasma concentrations of MR-proANP and NT-proBNP than sinus rhythm. Moreover, AF burden was associated with subsequent concentrations of both MR-proANP and NT-proBNP. The results suggest that natriuretic propeptide measurement reflects functional cardiac dysfunction during AF, and that AF burden should be included in biochemical assessment of left ventricular dysfunction.

A score for paroxysmal atrial fibrillation in acute ischemic stroke

Aim Many patients with ischemic stroke have paroxysmal atrial fibrillation that may be difficult to detect. We sought to identify markers of paroxysmal atrial fibrillation and construct a score that may help the clinician to select patients for anticoagulation even if investigations do not disclose atrial fibrillation. Methods A group of patients with acute ischemic stroke and TIA and documented paroxysmal atrial fibrillation was compared to a group of patients with ischemic stroke and TIA and no known paroxysmal atrial fibrillation and sinus rhythm on Holter monitoring. Clinical features, blood tests, ECG, and MRI findings were compared. Sensitivity and specificity of significant markers for paroxysmal atrial fibrillation were calculated. A simple score based on independent markers for paroxysmal atrial fibrillation was constructed. Results Out of 3480 patients with TIA or ischemic stroke, 237 (19%) had paroxysmal atrial fibrillation and 1002 (81%) had sinus rhythm. On univariate analyses, significant markers for paroxysmal atrial fibrillation included increasing age, females, prior ischemic stroke, myocardial infarction, other heart diseases, pathologic troponin, embolic stroke and stroke in different arterial territories (all P < .01). A score including age dichotomized at 75 years, cardiac disease and troponin was constructed. Conclusion We identified many markers for paroxysmal atrial fibrillation and constructed a score that may help the clinician to select patients for anticoagulation even if investigations do not disclose paroxysmal atrial fibrillation.

High-Sensitivity Troponin as a Biomarker in Heart Rhythm Disease

Biomarkers are important prognostic tools in various cardiovascular conditions, including coronary artery disease and heart failure. Although their utility in cardiac electrophysiology (EP) is less established, biomarkers may guide EP clinical practice by identifying patients at risk for developing arrhythmias and their complications, in addition to augmenting therapeutic decisions by targeting appropriate pharmacologic and interventional therapies to patients who may benefit most. In this review, we focus on the prognostic role of high-sensitivity cardiac troponin (hs-cTn) assays-which detect subclinical cardiac myocyte damage-in cardiac arrhythmias and their sequelae. We review the current literature on hs-cTn and its impact on various arrhythmia disease states and also provide suggestions for future research in this field. In conclusion, although the utility of hs-cTn assays remains at an investigational stage in cardiac EP, studies to date have suggested value as a prognostic biomarker in atrial fibrillation and as a screening marker for patients at high risk of sudden cardiac death (both in the general population and among those with hypertrophic cardiomyopathy).

Cancer antigen-125 plasma level as a biomarker of new-onset atrial fibrillation in postmenopausal women

OBJECTIVE

Plasma cancer antigen (CA)-125 is a tumour marker recently shown to be associated with systolic heart failure and new-onset atrial fibrillation (AF) after myocardial infarction. However, no reports have described the relationship between CA-125 and new-onset AF in healthy postmenopausal women. The aim of the present study was to evaluate the relationship between CA-125 and new-onset AF in postmenopausal women.

METHODS

Between 2005 and 2015, 2086 women, including 1012 postmenopausal women, visited our hospital for annual health check-ups. We excluded patients with systolic dysfunction, chronic inflammatory disease, chronic obstructive pulmonary disease, histories of AF or neoplastic diseases. A total of 746 postmenopausal women underwent thorough physical examinations, including those for biomarkers such as brain natriuretic peptide, high-sensitivity C-reactive protein (hs-CRP) and CA-125.

RESULTS

During the 10-year observation period, AF was documented in 31 participants (4.2%). The mean age of participants developing AF (75±6 years) was higher than that of those without AF (68±8 years). Participants developing AF showed significantly higher CA-125 (11.4±6.3 U/mL) and hs-CRP (0.10±0.11 mg/dL) levels than did those without AF (7.7±3.2 U/mL, p<0.01; 0.07±0.08 mg/dL, p<0.05). Cox regression analyses revealed ageing (HR 1.3; 95% CI 1.08 to 1.57; p<0.01) and plasma CA-125 levels (HR 1.29; 95% CI 1.10 to 1.51; p=0.02) as independent predictors of AF.

CONCLUSIONS

High CA-125 levels might be associated with new-onset AF in healthy postmenopausal women.

The changing circumstance of atrial fibrillation - progress towards precision medicine

The prevalence of atrial fibrillation (AF) in the general population is between 1% and 2% in the developed world and is higher in men than in women. The arrhythmia occurs much more commonly in the elderly, and the estimated lifetime risk of developing AF is one in four for men and women aged 40 years and above. Projected data from multiple population-based studies in the USA and Europe predict a two- to threefold increase in the number of AF patients by 2060. The high lifetime risk of AF and increased longevity underscore the important public health burden posed by this arrhythmia worldwide. AF has multiple aetiologies and a broad variety of presentations. The primary pathologies underlying or promoting the occurrence of AF vary more than for any other cardiac arrhythmia, ranging from autonomic imbalance to organic heart disease and metabolic disorders, such as diabetes mellitus, metabolic syndrome, hyperthyroidism and kidney disease, and lifestyle factors such as smoking, alcohol consumption and participation in endurance sports. Biomarkers are increasingly being investigated and, together with clinical and genetic factors, will eventually lead to a clinically valuable detailed classification of AF which will also incorporate pathophysiological determinants and mechanisms of the arrhythmia. In turn, this will allow the development and application of precision medicine to this troublesome arrhythmia.

High-Sensitivity Troponin I and Rhythm Outcome after Electrical Cardioversion for Persistent Atrial Fibrillation

OBJECTIVES

We hypothesised that high-sensitivity troponin I (hs-TnI) might predict long-term rhythm outcome after cardioversion for persistent atrial fibrillation (AF), and that maintenance of sinus rhythm and/or treatment with the angiotensin II type 1 receptor blocker candesartan would reduce hs-TnI levels.

METHODS

In a double-blind, placebo-controlled study, 171 patients referred for electrical cardioversion for AF were randomised to receive candesartan or placebo for 3-6 weeks before cardioversion and for 6 months after electrical cardioversion. Blood samples for analysis of hs-TnI (Abbott Diagnostics) were available in 129 patients at baseline and in 60 successfully cardioverted patients at study end.

RESULTS

Hs-TnI was detectable in all subjects, with a median value of 5.3 ng/l (25th percentile 3.7, 75th percentile 7.2). hs-TnI at baseline was not predictive of rhythm outcome 6 months after electrical cardioversion for persistent AF. Treatment with candesartan did not influence the levels of hs-TnI. hs-TnI was unchanged from baseline to study end in patients who maintained sinus rhythm [4.9 (3.7, 7.0) and 5.0 (4.0, 6.4) ng/l, respectively; p = 0.699).

CONCLUSIONS

hs-TnI did not predict AF recurrence after cardioversion. hs-TnI levels were unchanged in patients maintaining sinus rhythm for 6 months after electrical cardioversion. hs-TnI levels were not influenced by treatment with candesartan.

Cardiac Remodeling, Circulating Biomarkers and Clinical Events in Patients with a History of Atrial Fibrillation. Data from the GISSI-AF Trial

PURPOSE

Atrial fibrillation (AF) is the most common arrhythmia and has an increasing impact on public health because of its morbidity and mortality. Clinical and diagnostic tests to predict the recurrence of arrhythmia and clinical events before AF becomes permanent are still an open issue.

METHODS

307 out of 1442 patients in sinus rhythm, at high risk of recurrence of AF enrolled in the GISSI-AF study, participated in a substudy with echocardiographic and biohumoral evaluation at baseline and at 12-month follow-up. The relations between biomarker concentrations and echocardiographic parameters with study endpoints in 1 year, were analysed by a stepwise multivariable Cox model (entry criteria p < 0.5 and stay criteria p < 0.2).

RESULTS

The echocardiographic variables, cardiac markers and clinical variables considered in the statistical model indicated a higher concentration of NT-proBNP at baseline as the strongest factor related to time of first AF recurrence (HR 1.42; 95 %CI 1.23-1.46), first CV hospitalization (HR 1.58; 95 %CI 1.31-1.92) and increasing duration of recurrent AF (OR 2.16; 95 %CI 1.52-3.08). Valsartan treatment was not related to clinical events.

CONCLUSIONS

In patients in sinus rhythm with a history of AF a higher concentration of NT-proBNP at baseline was the strongest independent risk factor for first AF recurrence and its duration, and for the first hospital admission for cardiovascular reasons.

Evaluating the Atrial Myopathy Underlying Atrial Fibrillation: Identifying the Arrhythmogenic and Thrombogenic Substrate

Atrial disease or myopathy forms the substrate for atrial fibrillation (AF) and underlies the potential for atrial thrombus formation and subsequent stroke. Current diagnostic approaches in patients with AF focus on identifying clinical predictors with the evaluation of left atrial size by echocardiography serving as the sole measure specifically evaluating the atrium. Although the atrial substrate underlying AF is likely developing for years before the onset of AF, there is no current evaluation to identify the preclinical atrial myopathy. Atrial fibrosis is 1 component of the atrial substrate that has garnered recent attention based on newer MRI techniques that have been applied to visualize atrial fibrosis in humans with prognostic implications regarding the success of treatment. Advanced ECG signal processing, echocardiographic techniques, and MRI imaging of fibrosis and flow provide up-to-date approaches to evaluate the atrial myopathy underlying AF. Although thromboembolic risk is currently defined by clinical scores, their predictive value is mediocre. Evaluation of stasis via imaging and biomarkers associated with thrombogenesis may provide enhanced approaches to assess risk for stroke in patients with AF. Better delineation of the atrial myopathy that serves as the substrate for AF and thromboembolic complications might improve treatment outcomes. Furthermore, better delineation of the pathophysiologic mechanisms underlying the development of the atrial substrate for AF, particularly in its earlier stages, could help identify blood and imaging biomarkers that could be useful to assess risk for developing new-onset AF and suggest specific pathways that could be targeted for prevention.

Insular Cortex Lesions, Cardiac Troponin, and Detection of Previously Unknown Atrial Fibrillation in Acute Ischemic Stroke

Background and Purpose—

Detection rates of paroxysmal atrial fibrillation (AF) after acute ischemic stroke increase with duration of ECG monitoring. To date, it is unknown which patient group may benefit most from intensive monitoring strategies. Therefore, we aimed to identify predictors of previously unknown AF during in-hospital ECG monitoring.

Methods—

All consecutive patients with imaging-confirmed ischemic stroke admitted to our tertiary care hospital from February 2011 to December 2013 were registered prospectively. Patients received continuous bedside ECG monitoring for at least 24 hours. Detection of previously unknown AF during in-hospital ECG monitoring was obtained from medical records. Patients with AF on admission ECG or known history of AF were excluded from analysis.

Results—

Among 1228 patients (median age, 73 years; median National Institutes of Health Stroke Scale, 4; 43.4% women), previously unknown AF was detected in 114 (9.3%) during a median time of continuous ECG monitoring of 3 days (interquartile range, 2–4 days). Duration of monitoring ( P <0.01), older age ( P <0.01), history of hypertension ( P =0.03), insular cortex involvement ( P <0.01), and higher high-sensitivity cardiac troponin T ( P =0.04) on admission were independently associated with subsequent detection of AF in a multiple regression analysis. Addition of high-sensitivity cardiac troponin T, insular cortex stroke, or both to the CHADS2 score (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke [2P]) significantly improved c -statistics from 0.63 to 0.68 ( P =0.01), 0.70 ( P <0.01), and 0.72 ( P <0.001), respectively.

Conclusions—

Insular cortex involvement, higher admission high-sensitivity cardiac troponin T, older age, hypertension, and longer monitoring are associated with new detection of AF during in-hospital ECG monitoring. Patients with higher high-sensitivity cardiac troponin T or insular cortex involvement may be candidates for prolonged ECG monitoring.

Biomarkers in electrophysiology: role in arrhythmias and resynchronization therapy

Circulating biomarkers related to inflammation, neurohormones, myocardial stress, and necrosis have been associated with commonly encountered arrhythmic disorders such as atrial fibrillation (AF) and more malignant processes including ventricular arrhythmias (VA) and sudden cardiac death (SCD). Both direct and indirect biomarkers implicated in the heart failure cascade have potential prognostic value in patients undergoing cardiac resynchronization therapy (CRT). This review will focus on the role of biomarkers in AF, history of SCD, and CRT with an emphasis to improve clinical risk assessment for arrhythmias and patient selection for device therapy. Notably, information obtained from biomarkers may supplement traditional diagnostic and imaging techniques, thus providing an additional benefit in the management of patients.

High-sensitivity cardiac troponin T and the risk of incident atrial fibrillation: the Atherosclerosis Risk in Communities (ARIC) study

INTRODUCTION

Structural changes in the heart are known risk factors for atrial fibrillation (AF). An association between high-sensitivity cardiac troponin T (hs-cTnT), a marker of myocardial cell damage measured with a high-sensitivity assay, and the risk of AF could have implications for AF risk stratification.

OBJECTIVE

To estimate the association between hs-cTnT and the risk of incident AF in the ARIC study, a prospective cohort of middle-aged adults from 4 US communities.

METHODS

Study included 10,584 participants (mean age 62.7 years) free of AF in 1996 to 1998 and followed through 2008. Atrial fibrillation was defined using International Classification of Diseases codes from hospitalizations and death certificates. Participants with undetectable hs-cTnT levels (58%) were assigned the lower limit of measurement (5 ng/L). Net reclassification improvement was used to examine the discriminative ability of hs-cTnT for 10-year AF risk prediction (categories: <5%, 5%-15%, and >15%).

RESULTS

A total of 920 incident AF cases were observed for 109,227 person-years. After adjustment, a 1-SD difference in ln(hs-cTnT) was associated with a hazard ratio of 1.16 (95% CI 1.10-1.23). Compared with those with undetectable levels, participants with hs-cTnT ≥14 ng/L had a hazard ratio of 1.78 (95% CI 1.43-2.24). Addition of hs-cTnT to known AF predictors did not increase the c statistic appreciably (0.756 vs 0.758) or improve risk stratification (net reclassification improvement 0.4%, 95% CI -1.4% to 2.3%).

CONCLUSIONS

High-sensitivity cTnT level is associated with an increased incidence rate of AF but did not improve risk stratification.

Risk factors for atrial fibrillation recurrence: a literature review

Atrial fibrillation is the most common arrhythmia managed in clinical practice and it is associated with an increased risk of mortality, stroke and peripheral embolism. Unfortunately, the incidence of atrial fibrillation recurrence ranges from 40 to 50%, despite the attempts of electrical cardioversion and the administration of antiarrhythmic drugs. In this review, the literature data about predictors of atrial fibrillation recurrence are highlighted, with special regard to clinical, therapeutic, biochemical, ECG and echocardiographic parameters after electrical cardioversion and ablation. Identifying predictors of success in maintaining sinus rhythm after cardioversion or ablation may allow a better selection of patients to undergo these procedures. The aim is to reduce healthcare costs and avoid exposing patients to unnecessary procedures and related complications. Recurrent atrial fibrillation depends on a combination of several parameters and each patient should be individually assessed for such a risk of recurrence.

Multiple biomarkers and atrial fibrillation in the general population

Background

Different biological pathways have been related to atrial fibrillation (AF). Novel biomarkers capturing inflammation, oxidative stress, and neurohumoral activation have not been investigated comprehensively in AF.

Methods and Results

In the population-based Gutenberg Health Study (n = 5000), mean age 56±11 years, 51% males, we measured ten biomarkers representing inflammation (C-reactive protein, fibrinogen), cardiac and vascular function (midregional pro adrenomedullin [MR-proADM], midregional pro atrial natriuretic peptide [MR-proANP], N-terminal pro-B-type natriuretic peptide [Nt-proBNP], sensitive troponin I ultra [TnI ultra], copeptin, and C-terminal pro endothelin-1), and oxidative stress (glutathioneperoxidase-1, myeloperoxidase) in relation to manifest AF (n = 161 cases). Individuals with AF were older, mean age 64.9±8.3, and more often males, 71.4%. In Bonferroni-adjusted multivariable regression analyses strongest associations per standard deviation increase in biomarker concentrations were observed for the natriuretic peptides Nt-proBNP (odds ratio [OR] 2.89, 99.5% confidence interval [CI] 2.14–3.90; P<0.0001), MR-proANP (OR 2.45, 99.5% CI 1.91–3.14; P<0.0001), the vascular function marker MR-proADM (OR 1.54, 99.5% CI 1.20–1.99; P<0.0001), TnI ultra (OR 1.50, 99.5% CI 1.19–1.90; P<0.0001) and. fibrinogen (OR 1.44, 99.5% CI 1.19–1.75; P<0.0001). Based on a model comprising known clinical risk factors for AF, all biomarkers combined resulted in a net reclassification improvement of 0.665 (99.3% CI 0.441–0.888) and an integrated discrimination improvement of >13%.

Conclusions

In conclusion, in our large, population-based study, we identified novel biomarkers reflecting vascular function, MR-proADM, inflammation, and myocardial damage, TnI ultra, as related to AF; the strong association of natriuretic peptides was confirmed. Prospective studies need to examine whether risk prediction of AF can be enhanced beyond clinical risk factors using these biomarkers.

B-type natriuretic peptide and C-reactive protein in the prediction of atrial fibrillation risk: the CHARGE-AF Consortium of community-based cohort studies

AIMS

B-type natriuretic peptide (BNP) and C-reactive protein (CRP) predict atrial fibrillation (AF) risk. However, their risk stratification abilities in the broad community remain uncertain. We sought to improve risk stratification for AF using biomarker information.

METHODS AND RESULTS

We ascertained AF incidence in 18 556 Whites and African Americans from the Atherosclerosis Risk in Communities Study (ARIC, n=10 675), Cardiovascular Health Study (CHS, n = 5043), and Framingham Heart Study (FHS, n = 2838), followed for 5 years (prediction horizon). We added BNP (ARIC/CHS: N-terminal pro-B-type natriuretic peptide; FHS: BNP), CRP, or both to a previously reported AF risk score, and assessed model calibration and predictive ability [C-statistic, integrated discrimination improvement (IDI), and net reclassification improvement (NRI)]. We replicated models in two independent European cohorts: Age, Gene/Environment Susceptibility Reykjavik Study (AGES), n = 4467; Rotterdam Study (RS), n = 3203. B-type natriuretic peptide and CRP were significantly associated with AF incidence (n = 1186): hazard ratio per 1-SD ln-transformed biomarker 1.66 [95% confidence interval (CI), 1.56-1.76], P < 0.0001 and 1.18 (95% CI, 1.11-1.25), P < 0.0001, respectively. Model calibration was sufficient (BNP, χ(2) = 17.0; CRP, χ(2) = 10.5; BNP and CRP, χ(2) = 13.1). B-type natriuretic peptide improved the C-statistic from 0.765 to 0.790, yielded an IDI of 0.027 (95% CI, 0.022-0.032), a relative IDI of 41.5%, and a continuous NRI of 0.389 (95% CI, 0.322-0.455). The predictive ability of CRP was limited (C-statistic increment 0.003). B-type natriuretic peptide consistently improved prediction in AGES and RS.

CONCLUSION

B-type natriuretic peptide, not CRP, substantially improved AF risk prediction beyond clinical factors in an independently replicated, heterogeneous population. B-type natriuretic peptide may serve as a benchmark to evaluate novel putative AF risk biomarkers.

Relation between soluble ST2, growth differentiation factor-15, and high-sensitivity troponin I and incident atrial fibrillation

BACKGROUND

We investigated whether circulating concentrations of soluble ST2, growth differentiation factor-15 (GDF-15), and high-sensitivity troponin I (hsTnI) are associated with incident atrial fibrillation (AF) and whether these biomarkers improve current risk prediction models including AF risk factors, B-type natriuretic peptide (BNP), and C-reactive protein (CRP).

METHODS

We studied the relation between soluble ST2, GDF-15, and hsTnI and development of AF in Framingham Heart Study participants without prevalent AF. We used Cox proportional hazard regression analysis to examine the relation of incident AF during a 10-year follow-up period with each biomarker. We adjusted for standard AF clinical risk factors, BNP, and CRP.

RESULTS

The mean age of the 3,217 participants was 59 ± 10 years, and 54% were women. During a 10-year follow-up, 242 participants developed AF. In age- and sex-adjusted models, GDF-15 and hsTnI were associated with risk of incident AF; however, after including the AF risk factors and BNP and CRP, only hsTnI was significantly associated with AF (hazard ratio per 1 SD of loge hsTnI, 1.12, 95% CI 1.00-1.26, P = .045). The c statistic of the base model including AF risk factors, BNP, and CRP was 0.803 (95% CI 0.777-0.830) and did not improve by adding individual or all 3 biomarkers. None of the discrimination and reclassification statistics were significant compared with the base model.

CONCLUSION

In a community-based cohort, circulating hsTnI concentrations were associated with incident AF. None of the novel biomarkers evaluated improved AF risk discrimination or reclassification beyond standard clinical AF risk factors and biomarkers.

Natriuretic Peptides as Predictors of Atrial Fibrillation Recurrences Following Electrical Cardioversion

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

Rhythm outcomes after catheter ablation of atrial fibrillation. Clinical implication of biomarkers

Atrial fibrillation (AF) occurs as the result of numerous complex physiological processes in the atria leading to AF promotion and maintenance. Improved diagnostic techniques have identified various biomarkers which may play an important role in the prediction of AF related outcomes (cardio- and cerebrovascular events, as well as mortality and rhythm outcomes). Biomarkers refer to 'biological markers' and biomarkers in blood, urine as well as imaging marker (eg, dimensions (left atrial diameter and volume), anatomical features (left appendage and pulmonary vein anatomy), and physiological pattern (LAA flow velocity)) may play important role(s) as clinically important indices in relation to outcomes after different therapeutic strategies. However, the main domain in the biomarker field has focused on blood-based biomarkers, which are widely used to predict therapeutic success regarding underlying pathophysiological mechanism, such as inflammation, fibrosis, endothelial damage. This review provides an update of the role of clinically relevant biomarkers in AF, with particular focus on AF rhythm outcomes.

Recent developments in understanding epidemiology and risk determinants of atrial fibrillation as a cause of stroke

The prevalence of atrial fibrillation (AF) is increasing because of the aging population and advances in the treatment of acute cardiac conditions. It is now approaching epidemic proportions and is associated with significant clinical and public health consequences. Risk factors for the development of AF are numerous and varied and highlight potential treatment measures that could help prevent the occurrence of AF. The emergence of novel risk factors might allow us to increase our understanding of the pathophysiology of the condition and develop novel therapeutic targets. Stroke is the most devastating consequence of AF, and can be prevented with effective oral anticoagulation in patients at increased stroke risk. Our understanding of stroke risk has advanced; we know that the risk is not homogenous and also that only the very lowest risk patients do not benefit from anticoagulation. Clinicians should target their efforts on identifying this "truly low-risk" patient cohort and consider offering formal anticoagulation to all other AF patients. The purpose of this review is to consider the traditional and emerging risk factors for the development of AF itself, and the risk factors for stroke in AF patients and how knowledge of these risk factors can affect clinical practice.

Family history as a risk factor for recurrent hospitalization for lone atrial fibrillation: a nationwide family study in Sweden

BACKGROUND

Although the heritability of atrial fibrillation (AF) has been determined, the relevance of family history of AF for the likelihood of recurrent hospitalization for AF is unknown. The aim of this nationwide study was to determine whether family history of AF is a risk factor of recurrent hospitalization for lone AF (LAF), i.e., AF with unknown etiology. The familial risk for first time LAF hospitalization was also determined and compared to the risk of recurrent hospitalization for LAF.

METHODS

We examined whether family history of AF is a risk factor for recurrent hospitalization for LAF in the whole Swedish population. We linked Multigeneration Register data on individuals aged 0-60 years to Hospital Discharge Register data for the period 1987-2009 to compare LAF recurrent hospitalization risk among individuals with and without parental or sibling history of AF. We calculated hazard ratios (HRs) to determine the familial HR of recurrent hospitalization for LAF. Odds ratios (OR) were calculated for familial risk of first time LAF hospitalization.

RESULTS

The risk of recurrent LAF hospitalization was 1.23 (95% CI 1.17-1.30) for individuals with affected parents compared to 1.30 (95% CI 1.22-1.38) for those with affected siblings. After 10 years of follow up 50% of those without and 60% of those with family history had recurrent hospitalization for LAF. The risk of recurrent LAF hospitalization in individuals with two affected parents was 1.65 (95% CI 1.44-1.90). There was an interaction between age and family history, with family history having a weaker effect on LAF hospitalization risk in older age groups. The OR for first time LAF hospitalization was 2.08 (95% CI 2.02-2.15) for offspring with affected parents and 3.23 (95% CI 3.08-3.39) for individuals with affected siblings.

CONCLUSIONS

Family history of AF is a novel risk factor for recurrent LAF hospitalization. The higher recurrence hospitalization risk in multiplex families and younger individuals suggests a genetic contribution. However, the familial risk for recurrent LAF hospitalization was much lower than the risk for first time LAF hospitalization, suggesting that familial and possibly genetic factors are more important for first time LAF hospitalization than recurrent LAF hospitalization.

The expression levels of plasma micoRNAs in atrial fibrillation patients

BACKGROUND

MicroRNA (miRNA) has been found in human blood. It has been increasingly suggested that miRNAs may serve as biomarkers for diseases. We examined the potential of circulating miRNA to serve as predictors of atrial fibrillation (AF).

METHODOLOGY/PRINCIPAL FINDINGS

During the discovery stage of this project, we used massively parallel signature sequencing (MPSS) to carry out an in-depth analysis of the miRNA expression profile (miRNome) in 5 healthy controls, 5 patients with paroxysmal atrial fibrillation (PAF) alone, and 5 patients with persistent atrial fibrillation (PersAF) alone. Twenty-two specific miRNAs were found to be dysregulated in each PAF group, PersAF group, or control group. Four candidate microRNAs (miRNA-146a, miRNA-150, miRNA-19a, and miRNA-375) met our selection criteria and were evaluated in an independent cohort of 90 plasma samples using TaqMan miRNA quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). We found miRNA-150 levels to be reduced by a factor of approximately 17 in PAF relative to controls and a factor of approximately 20 in PersAF relative to controls (P<.0001). Logistic regression analyses were carried out to evaluate the reduced miRNA-150 expression levels (odds ratio [OR] 1.96, 95% confidence interval [CI] 1.5 to 3.57, P<0.001), age (OR 1.1, 95% CI 1.36 to 2.73, P<0.001), and Left atrial diameter (LAD) (OR 1.5, 95% CI 1.36 to 1.8, P<0.001). Each was independently associated with AF. Much of the identified target genes related to AF were part of the inflammatory response system. We found that plasma levels of CRP were negatively correlated with the plasma levels of miRNA-150.

CONCLUSIONS/SIGNIFICANCE

In summary, we firstly found that plasma miRNA-150 levels in from AF patients were substantially lower than that from healthy people. Circulating reduced miRNA-150 was significantly associated with AF.

The predictive value of C-reactive protein on recurrence of atrial fibrillation after cardioversion with or without treatment with atorvastatin

BACKGROUND

The aim of this study was to investigate whether high-sensitivity C-reactive protein (hsCRP) levels prior to cardioversion (CV) predict recurrence of atrial fibrillation (AF) in patients randomized to treatment with either atorvastatin or placebo 30 and 180 days after CV.

METHODS

This was a prespecified substudy of 128 patients with persistent AF randomized to treatment with atorvastatin 80 mg/day or placebo, initiated 14 days before CV, and continued 30 days after CV. HsCRP levels were measured at randomization, at the time of CV, and 2 days and 30 days after CV.

RESULTS

In univariate analysis of those who were in sinus rhythm 2h after CV, hsCRP did not significantly (odds ratio [OR] 1.11, 95% confidence interval [CI] 0.99-1.25) predict recurrence of AF at 30 days. However, after adjusting for treatment with atorvastatin, hsCRP predicted the recurrence of AF (OR 1.14, 95% CI 1.01-1.27). In a multivariate logistic regression analysis with gender, age, body mass index (BMI), smoking, cholesterol, and treatment with atorvastatin as covariates, the association was still significant (OR 1.14, 95% CI 1.01-1.29). Six months after CV, hsCRP at randomization predicted recurrence of AF in both univariate analysis (OR 1.30, 95% CI 1.06-1.60) and in multivariate logistic regression analysis (OR 1.33, 95% CI 1.06-1.67).

CONCLUSION

HsCRP was associated with AF recurrence one and six months after successful CV of persistent AF. However, the association at one month was significant only after adjusting for atorvastatin treatment.