Biomarkers of Atrial Fibrillation: Which One Is a True Marker?

Biomarkers for predicting atrial fibrillation: An explorative sub-analysis of the randomised SCREEN-AF trial

BACKGROUND

Atrial fibrillation (AF) is a common treatable risk factor for stroke. Screening for paroxysmal AF in general practice is difficult, but biomarkers might help improve screening strategies.

OBJECTIVES

We investigated six blood biomarkers for predicting paroxysmal AF in general practice.

METHODS

This was a pre-specified sub-study of the SCREEN-AF RCT done in Germany. Between 12/2017-03/2019, we enrolled ambulatory individuals aged 75 years or older with a history of hypertension but without known AF. Participants in the intervention group received active AF screening with a wearable patch, continuous ECG monitoring for 2x2 weeks and usual care in the control group. The primary endpoint was ECG-confirmed AF within six months after randomisation. High-sensitive Troponin I (hsTnI), brain natriuretic peptide (BNP), N-terminal pro-B-type natriuretic peptide (NT-pro BNP), N-terminal pro atrial natriuretic peptide (NT-ANP), mid-regional pro atrial natriuretic peptide (MR-pro ANP) and C-reactive protein (CRP) plasma levels were investigated at randomisation for predicting AF within six months after randomisation.

RESULTS

Blood samples were available for 291 of 301 (96.7%) participants, including 8 with AF (3%). Five biomarkers showed higher median results in AF-patients: BNP 78 vs. 41 ng/L (p = 0.012), NT-pro BNP 273 vs. 186 ng/L (p = 0.029), NT-proANP 4.4 vs. 3.5 nmol/L (p = 0.027), MR-pro ANP 164 vs. 125 pmol/L (p = 0.016) and hsTnI 7.4 vs. 3.9 ng/L (p = 0.012). CRP levels were not different between groups (2.8 vs 1.9 mg/L, p = 0.1706).

CONCLUSION

Natriuretic peptide levels and hsTnI are higher in patients with AF than without and may help select patients for AF screening, but larger trials are needed.

Effect of an Intensive Lifestyle Intervention on Circulating Biomarkers of Atrial Fibrillation-Related Pathways among Adults with Metabolic Syndrome: Results from a Randomized Trial

Background: Lifestyles influence atrial fibrillation (AF) risk. Determining the effect of lifestyle interventions on blood concentrations of biomarkers of AF-related pathways could help understand AF pathophysiology and contribute to AF prevention. Methods: We studied 532 participants enrolled in the PREDIMED-Plus trial, a Spanish randomized trial conducted in adults (55-75 years) with metabolic syndrome and body mass index between 27-40 kg/m2. Eligible participants were randomized 1:1 to an intensive lifestyle intervention, emphasizing physical activity, weight loss, and adherence to an energy-reduced Mediterranean diet or to a control group. Serum biomarkers [carboxy-terminal propeptide of procollagen type I (PICP), high-sensitivity troponin T (hsTnT), high-sensitivity C reactive protein (hsCRP), 3-nitrotyrosine (3-NT), and N-terminal propeptide of B-type natriuretic peptide (NT-proBNP)] were measured at baseline, 3 and 5 years after randomization. Mixed models were used to evaluate the effect of intervention on changes in biomarkers through year 5. Mediation analysis was performed to examine the proportion mediated by each component of the intervention. Results: At baseline, participants' mean age was 65, 40% were female, and 50% were assigned to the intervention. After five years, mean changes in log-transformed biomarkers were -0.01 (PICP), 0.20 (hsTnT), -0.17 (hsCRP), 0.12 (3-NT), and 0.27 (NT-proBNP). Compared to the control group, participants in the intervention group experienced greater decreases in hsCRP (-14%, 95% confidence interval (CI) -26%, 0%) or smaller increases in 3-NT (-16%, 95% CI -25%, -5%) and NT-proBNP (-12%, 95% CI -23%, 1%). The intervention had minimal impact on hsTnT (-3%, 95% CI -7%, 2%) or PICP concentrations (-2%, 95% CI -9%, 6%). The effect of the intervention on hsCRP was primarily mediated by weight loss (89% at year 5). Conclusions: Over five years, a dietary and lifestyle intervention for weight-loss favorably affected concentrations of hsCRP, 3-NT, and NT-proBNP, pointing to specific mechanisms in pathways linking lifestyles and AF.

Evaluation of troponin I serum levels in patients with arrhythmias with and without coronary artery disease

BACKGROUND

Elevated levels of cardiac enzymes in the blood are an indicator of ongoing cardiac ischemia. Persistent tachycardia may lead to myocardial ischemia due to oxygen supply-demand mismatch.

OBJECTIVES

We sought to evaluate the probability of underlying coronary artery disease (CAD) in patients with symptomatic supraventricular (SVT) or ventricular tachyarrhythmias (VT) based on cardiac enzyme level fluctuation.

MATERIALS AND METHODS

Troponin I (TNI) levels were measured twice and coronary angiography was also performed in patients without a history of cardiovascular disease and symptomatic SVT or VT.

RESULTS

Of the 114 (group A: CAD (n = 40), group B: no CAD (n = 74)) patients eligible for the study, 34 patients in group A and 64 patients in group B had SVT, while 6 patients in group A and 10 patients in group B had VT. All patients with underlying CAD developed a significantly elevated TNI level compared to baseline, irrespective of arrhythmia type (2.02 ± 7.98 ng/ml vs. 5.64 ± 13.38, p = 0.031). In patients without CAD, TNI level was not significantly elevated compared to the baseline level, irrespective of arrhythmia type (0.34 ± 1.38 ng/ml vs. 0.48 ± 1.48 ng/ml, p = 0.158). Most patients with normal TNI levels (46 of 47 patients; 98 %) had SVT. CAD was present in 13 of 47 patients (27 %) with tachycardia, despite normal TNI levels.

CONCLUSIONS

Elevated TNI levels are not helpful to discriminate between SVT and VT. An increase in TNI level in repeated blood sampling can help identify patients with higher probability of underlying CAD. Patients with VT demonstrated higher increases in TNI levels, compared to patients with SVT.

Effect of an intensive lifestyle intervention on circulating biomarkers of atrial fibrillation-related pathways among adults with metabolic syndrome

Background Lifestyles influence atrial fibrillation (AF) risk. Blood biomarkers can characterize the atrial substrate that facilitates the development of AF. Therefore, determining the effect of lifestyle interventions on blood concentrations of biomarkers of AF-related pathways could help understand AF pathophysiology and contribute to AF prevention. Methods We studied 471 participants enrolled in the PREDIMED-Plus trial, a Spanish randomized trial conducted in adults (55-75 years) with metabolic syndrome and body mass index between 27-40 kg/m2. Eligible participants were randomized 1:1 to an intensive lifestyle intervention, emphasizing physical activity, weight loss, and adherence to an energy-reduced Mediterranean diet or to a control group. Serum biomarkers [carboxy-terminal propeptide of procollagen type I (PICP), high-sensitivity troponin T (hsTnT), high-sensitivity C reactive protein (hsCRP), 3-nitrotyrosine (3-NT), and N-terminal propeptide of B-type natriuretic peptide (NT-proBNP)] were measured at baseline, 3 and 5 years after randomization. Mixed models were used to evaluate the effect of intervention on changes in biomarkers through year 5. Mediation analysis was performed to examine the proportion mediated by each component of the intervention. Results At baseline, participants' mean age was 65, 41% were female, and 50% were assigned to the intervention. After five years, mean changes in log-transformed biomarkers were -0.03 (PICP), 0.19 (hsTnT), -0.15 (hsCRP), 0.12 (3-NT), and 0.30 (NT-proBNP). Compared to the control group, participants in the intervention group experienced greater decreases in hsCRP (-16%, 95% confidence interval (CI) -28%, -1%) or smaller increases in 3-NT (-15%, 95% CI -25%, -4%) and NT-proBNP (-13%, 95% CI -25%, 0%). The intervention had minimal impact on hsTnT (-3%, 95% CI -8%, 2%) or PICP concentrations (-0%, 95% CI -9%, 9%). The effect of the intervention on hsCRP was primarily mediated by weight loss (73% and 66% at years 3 and 5). Conclusion Over five years, a dietary and lifestyle intervention for weight-loss favorably affected concentrations of hsCRP, 3-NT, and NT-proBNP, pointing to specific mechanisms in pathways linking lifestyles and AF.

microRNAs as Biomarkers of Endothelial Dysfunction and Therapeutic Target in the Pathogenesis of Atrial Fibrillation

The pathophysiology of atrial fibrillation (AF) may involve atrial fibrosis/remodeling and dysfunctional endothelial activities. Despite the currently available treatment approaches, the progression of AF, its recurrence rate, and the high mortality risk of related complications underlay the need for more advanced prognostic and therapeutic strategies. There is increasing attention on the molecular mechanisms controlling AF onset and progression points to the complex cell to cell interplay that triggers fibroblasts, immune cells and myofibroblasts, enhancing atrial fibrosis. In this scenario, endothelial cell dysfunction (ED) might play an unexpected but significant role. microRNAs (miRNAs) regulate gene expression at the post-transcriptional level. In the cardiovascular compartment, both free circulating and exosomal miRNAs entail the control of plaque formation, lipid metabolism, inflammation and angiogenesis, cardiomyocyte growth and contractility, and even the maintenance of cardiac rhythm. Abnormal miRNAs levels may indicate the activation state of circulating cells, and thus represent a specific read-out of cardiac tissue changes. Although several unresolved questions still limit their clinical use, the ease of accessibility in biofluids and their prognostic and diagnostic properties make them novel and attractive biomarker candidates in AF. This article summarizes the most recent features of AF associated with miRNAs and relates them to potentially underlying mechanisms.

Biomarkers Utility: At the Borderline between Cardiology and Neurology

Biomarkers are important diagnostic and prognostic tools as they provide results in a short time while still being an inexpensive, reproducible and accessible method. Their well-known benefits have placed them at the forefront of research in recent years, with new and innovative discoveries being implemented. Cardiovascular and neurological diseases often share common risk factors and pathological pathways which may play an important role in the use and interpretation of biomarkers' values. Among the biomarkers used extensively in clinical practice in cardiology, hs-TroponinT, CK-MB and NTproBNP have been shown to be strongly influenced by multiple neurological conditions. Newer ones such as galectin-3, lysophosphatidylcholine, copeptin, sST2, S100B, myeloperoxidase and GDF-15 have been extensively studied in recent years as alternatives with an increased sensitivity for cardiovascular diseases, but also with significant results in the field of neurology. Thus, given their low specificity, the values interpretation must be correlated with the clinical judgment and other available investigations.

Prognostic Value of Troponin in Patients with Atrial Fibrillation Admitted to an Emergency Department: Review and Meta-Analysis

Introduction

Elevated levels of cardiac troponin (cTn) indicate underlying heart disease and is known to predict adverse events in multiple conditions. Its role in atrial fibrillation (AF) in the acute setting is still not conclusive. We aimed to assess the prognostic value of c-Tn in patients with AF admitted to an emergency department (ED).

Methods

Systematic searches were conducted using PubMed and the Cochrane Library and the International Clinical Trials Registry Platform to identify studies from year 2009 to October 2019 reporting on the prognostic value of cTn on all-cause mortality or major adverse cardiac events (MACE) in adult patients with AF in the ED. We pooled hazard ratio (HR) and 95% confidence interval (CI) using fixed and random effects models according the heterogeneity. We planned to conduct a sensitivity and subgroup analyses.

Results

Five studies involving 5750 patients were identified. The mean follow-up ranged from 12 to 35 months. An increase in mortality was observed in the elevated cTn group compared to the controls, HR=2.7 (95% CI 1.55-4.72), P for effect<0.001, I2=80%). For MACE, the pooled HR was 2.17 (95%CI 1.60-2.94), P for effect<0.001, I2=0%). In the subgroup analysis we found no significant difference in type of troponin used and study design.

Conclusions

The elevation of cardiac troponin was significantly associated with higher mortality and major adverse cardiac events in patients with AF admitted to an ED. In this setting the use of c-Tn could provide prognostic information.

Blood-based 8-hydroxy-2'-deoxyguanosine level: A potential diagnostic biomarker for atrial fibrillation

BACKGROUND

Recent research findings have revealed a key role of oxidative DNA damage in the pathogenesis of atrial fibrillation (AF). Therefore, the circulating oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) may represent a biomarker for staging AF and identifying patients at risk for AF recurrence and postoperative atrial fibrillation (POAF) after treatment.

OBJECTIVE

The purpose of this study was to investigate whether serum levels of 8-OHdG correlate with the stage of AF, recurrence after AF treatment, and onset of POAF after cardiac surgery.

METHODS

In this prospective observational study, 8-OHdG levels were detected by enzyme-linked immunosorbent assay in human serum samples. Blood samples were collected from control patients without AF history; patients with paroxysmal AF and persistent AF undergoing electrical cardioversion or pulmonary vein isolation (PVI); and patients with sinus rhythm (SR) undergoing cardiac surgery. AF recurrence was determined during 12-month follow-up. Univariate and multivariate analyses were used to identify changes in 8-OHdG levels between the groups.

RESULTS

Compared to the control group, 8-OHdG levels in the patient groups gradually and significantly increased during arrhythmia progression. 8-OHdG levels in AF patients showing AF recurrence after PVI treatment were significantly increased compared to patients without AF recurrence. Moreover, in SR patients undergoing cardiac surgery, 8-OHdG levels were significantly elevated in those showing POAF compared to patients without POAF.

CONCLUSION

8-OHdG level may represent a potential diagnostic biomarker for AF staging as well as for predicting AF recurrence and POAF after treatment.

Genome-wide analysis of circular RNA expression profiles in patients with atrial fibrillation

Atrial fibrillation (AF) is one of the most common clinical cardiac arrhythmias. This study was done to screen differentially expressed circular RNAs (circRNAs) in human monocytes from patients with AF and healthy controls using microarray, and preliminarily explore the role of circRNAs in the development of AF. The expression of circRNAs in peripheral blood monocytes of 4 AF patients and 4 healthy donors was detected by chip technology and validated by qRT-PCR. Differentially expressed genes were screened out. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to identify the function of differentially expressed genes and related pathways. Potential connections between circRNAs and miRNAs were explored by using Cytoscape. 120 differentially expressed circRNAs (FC≥2, P<0.05) were preliminarily screened by circRNA microarray, of which 65 were up-regulated and 55 down-regulated. All of 4 upregulated circRNAs (circRNA_0031, circRNA_1837, circRNA_5901 and circRNA_7571) and 3 out of 4 downregulated circRNAs (circRNA_5801, circRNA_7386 and circRNA_7577) were randomly confirmed by RT-PCR. GO and KEGG analysis suggested that differentially expressed circRNA-related genes are mainly involved in inflammation, immunity, and signaling transduction. CircRNA_7571, circRNA_4648, circRNA_4631 and circRNA_2875 were the first 4 circRNAs with the most binding nodes in the co-expression network. In addition, hsa-miR-328 was the highest positively correlated miRNA in the networks. Our findings demonstrated that there were differentially expressed circRNAs in human monocytes from AF patients. circRNA_7571, circRNA_4648, circRNA_4631 and circRNA_2875 were the first 4 circRNAs with the most binding nodes in the co-expression network. hsa-miR-328 was the largest node that interacted with circRNAs in the co-expression network. circRNAs-hsa-miR-328 network may play a critical role in the pathophysiology and mechanism of AF.

Exploratory Analysis of Circulating miRNA Signatures in Atrial Fibrillation Patients Determining Potential Biomarkers to Support Decision-Making in Anticoagulation and Catheter Ablation

Novel biomarkers are desired to improve risk management for patients with atrial fibrillation (AF). We measured 179 plasma miRNAs in 83 AF patients using multiplex qRT-PCR. Plasma levels of eight (i.e., hsa-miR-22-3p, hsa-miR-128-3p, hsa-miR-130a-3p, hsa-miR-140-5p, hsa-miR-143-3p, hsa-miR-148b-3p, hsa-miR-497-5p, hsa-miR-652-3p) and three (i.e., hsa-miR-144-5p, hsa-miR-192-5p, hsa-miR-194-5p) miRNAs showed positive and negative correlations with CHA₂DS₂-VASc scores, respectively, which also showed negative and positive correlations with catheter ablation (CA) procedure, respectively, within the follow-up observation period up to 6-month after enrollment. These 11 miRNAs were functionally associated with TGF-β signaling and androgen signaling based on pathway enrichment analysis. Seven of possible target genes of these miRNAs, namely TGFBR1, PDGFRA, ZEB1, IGFR1, BCL2, MAPK1 and DICER1 were found to be modulated by more than four miRNAs of the eleven. Of them, TGFBR1, PDGFRA, ZEB1 and BCL2 are reported to exert pro-fibrotic functions, suggesting that dysregulations of these eleven miRNAs may reflect pro-fibrotic condition in the high-risk patients. Although highly speculative, these miRNAs may potentially serve as potential biomarkers, providing mechanistic and quantitative information for pathophysiology in daily clinical practice with AF such as possible pro-fibrotic state in left atrium, which would enhance the risk of stroke and reduce the preference for performing CA.