N-terminal pro B-type natriuretic peptide in systematic screening for atrial fibrillation

Randomised, siteless study to compare systematic atrial fibrillation screening using enrichment by a risk prediction model with standard care in a Swedish population aged ≥ 65 years: CONSIDERING-AF study design

INTRODUCTION

Atrial fibrillation (AF) is the most common arrhythmia and confers an increased risk of mortality, stroke, heart failure and cognitive decline. There is growing interest in AF screening; however, the most suitable population and device for AF detection remains to be elucidated. Here, we present the design of the CONSIDERING-AF (deteCtiON and Stroke preventIon by moDEl scRreenING for Atrial Fibrillation) study.

METHODS AND ANALYSIS

CONSIDERING-AF is a randomised, controlled, siteless, non-blinded diagnostic superiority trial with four parallel groups and a primary endpoint of identifying AF during a 6-month study period set in Region Halland, Sweden. In each group, 740 individuals aged≥65 years will be included. The primary objective is to compare the intervention of AF screening enrichment using a risk prediction model (RPM), followed by 14 days of a continuous ECG patch, with no intervention (standard care). Primary outcome is defined as the incident AF recorded in the Region Halland Information Database after 6 months as compared with standard care. Secondary endpoints include the difference in incident AF between groups enriched or not by the RPM, with and without an invitation to 14 days of continuous ECG recording, and the proportions of oral anticoagulation treatment in the four groups.

ETHICS AND DISSEMINATION

This study has ethical approval from the Swedish Ethical Review Authority. Results will be published in peer-reviewed international journals.

TRIAL REGISTRATION NUMBER

NCT05838781.

Electrocardiographic Predictors of Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common pathological arrhythmia, and its complications lead to significant morbidity and mortality. However, patients with AF can often go undetected, especially if they are asymptomatic or have a low burden of paroxysms. Identification of those at high risk of AF development may help refine screening and management strategies.

METHODS

PubMed and Embase databases were systematically searched for studies looking at electrocardiographic predictors of AF from inception to August 2021.

RESULTS

A total of 115 studies were reported which examined a combination of atrial and ventricular parameters that could be electrocardiographic predictors of AF. Atrial predictors include conduction parameters, such as the PR interval, p-wave index and dispersion, and partial interatrial or advanced interatrial block, or morphological parameters, such as p-wave axis, amplitude and terminal force. Ventricular predictors include abnormalities in QRS amplitude, morphology or duration, QT interval duration, r-wave progression and ST segment, i.e., t-wave abnormalities.

CONCLUSIONS

There has been significant interest in electrocardiographic prediction of AF, especially in populations at high risk of atrial AF, such as those with an embolic stroke of undetermined source. This review highlights the breadth of possible predictive parameters, and possible pathological bases for the predictive role of each parameter are proposed.

Atrial Fibrillation, thromboembolic risk, and the potential role of the natriuretic peptides, a focus on BNP and NT-proBNP - A narrative review

Atrial fibrillation (AF) is one of the most commonly encountered arrythmia in clinical practice. AF itself can be driven by genetic predisposition, ectopic electrical activity, and abnormal atrial tissue substrates. Often there is no single etiological mechanism, but rather a combination of factors that feed back to remodel and worsen tissue substrate, "AF begets AF". The clinical consequences of AF can often include emboli, heart failure, and early mortality. The classical AF cardioembolic (CE) concept requires thrombus formation in the left atrial appendage, with subsequent embolization. The temporal dissociation between AF occurrence and CE events has thrown doubt on AF as the driver of this mechanism. Instead, there has been a resurgence of the "atrial cardiomyopathy" (ACM) concept. An ACM is proposed as a potential mechanism of embolic disease through promotion of prothrombotic mechanisms, with AF instead reflecting atrial disease severity. Regardless, AF has been implicated in 25% to 30% of cryptogenic strokes. Natriuretic peptide(NP)s have been shown to be elevated in AF, with higher levels of both NT-proBNP and BNP being predictive of incidental AF. NPs potentially reflect the atrial environment and could be used to identify an underlying ACM. Therefore, this narrative review examines this evidence and mechanisms that may underpin the role of NPs in identifying atrial dysfunction, with focus on both, BNP and NTproBNP. We explore their potential role in the prediction and screening for both, ACM and AF. Moreover, we compare both NPs directly to ascertain a superior biomarker.

Neurologist-Led Management of Implantable Loop-Recorders After Embolic Stroke of Undetermined Source

Introduction

Upon completion of the workup for stroke, etiology cannot be identified in approximately one-third of the patients, with an embolic stroke of undetermined source (ESUS) accounting for around 50% of these cryptogenic etiologies. Whether management of complex long-term monitoring in order to detect suspected atrial fibrillation (AFib) could be initiated and managed through a neurologist is not sufficiently investigated.

Patients and Methods

We recruited all consecutive patients with ESUS who received implantation after neurological adjudication of Reveal LINQ^® loop recorder between January 2016 and July 2020. We collected demographic, clinical, heart- and neuroimaging, laboratory, and electrocardiographic data assessed on prolonged baseline ECG monitoring, number of supraventricular (SVEs) and ventricular (VEs) extrasystolic complexes, and from preimplantation ECG–PQ interval. AFib detection was manually supervised and determined positive when the duration was over 120 s.

Results

We followed a total of 131 patients for a median of 504 days. There were 45 (34%) manually verified AFib diagnoses. In univariate analysis, earlier implantation after ESUS was associated with AFib detection (13 vs. 31 days, p = 0.011). In multivariate analysis, increased rate of AFib was associated with a more prolonged PQ interval (per 50-ms increase) (HR 1.99, 95% CI 1.39–2.85) and number of SVEs (HR 1.29, 95% CI 1.05–1.57) measured on pre-implantation ECG.

Conclusion

We observed similar predictors for Afib after ESUS, albeit with higher frequency than previously reported. This study suggests that the neurologist-led decision, management, and evaluation of ILR after ESUS is feasible.

Risk prediction of atrial fibrillation in the community combining biomarkers and genetics

AIMS

Classical cardiovascular risk factors (CVRFs), biomarkers, and common genetic variation have been suggested for risk assessment of atrial fibrillation (AF). To evaluate their clinical potential, we analysed their individual and combined ability of AF prediction.

METHODS AND RESULTS

In N = 6945 individuals of the FINRISK 1997 cohort, we assessed the predictive value of CVRF, N-terminal pro B-type natriuretic peptide (NT-proBNP), and 145 recently identified single-nucleotide polymorphisms (SNPs) combined in a developed polygenic risk score (PRS) for incident AF. Over a median follow-up of 17.8 years, n = 551 participants (7.9%) developed AF. In multivariable-adjusted Cox proportional hazard models, NT-proBNP [hazard ratio (HR) of log transformed values 4.77; 95% confidence interval (CI) 3.66-6.22; P < 0.001] and the PRS (HR 2.18; 95% CI 1.88-2.53; P < 0.001) were significantly related to incident AF. The discriminatory ability improved asymptotically with increasing numbers of SNPs. Compared with a clinical model, AF risk prediction was significantly improved by addition of NT-proBNP and the PRS. The C-statistic for the combination of CVRF, NT-proBNP, and the PRS reached 0.83 compared with 0.79 for CVRF only (P < 0.001). A replication in the Dutch Prevention of REnal and Vascular ENd-stage Disease (PREVEND) cohort revealed similar results. Comparing the highest vs. lowest quartile, NT-proBNP and the PRS both showed a more than three-fold increased AF risk. Age remained the strongest risk factor with a 16.7-fold increased risk of AF in the highest quartile.

CONCLUSION

The PRS and the established biomarker NT-proBNP showed comparable predictive ability. Both provided incremental predictive value over standard clinical variables. Further improvements for the PRS are likely with the discovery of additional SNPs.

Stepwise mass screening for atrial fibrillation using N-terminal B-type natriuretic peptide: the STROKESTOP II study

Aims

To study the prevalence of unknown atrial fibrillation (AF) in a high-risk, 75/76-year-old, population using N-terminal B-type natriuretic peptide (NT-proBNP) and handheld electrocardiogram (ECG) recordings in a stepwise screening procedure.

Methods and results

The STROKESTOP II study is a population-based cohort study in which all 75/76-year-old in the Stockholm region (n = 28 712) were randomized 1:1 to be invited to an AF screening programme or to serve as the control group. Participants without known AF had NT-proBNP analysed and were stratified into low-risk (NT-proBNP <125 ng/L) and high-risk (NT-proBNP ≥125 ng/L) groups. The high-risk group was offered extended ECG-screening, whereas the low-risk group performed only one single-lead ECG recording. In total, 6868 individuals accepted the screening invitation of which 6315 (91.9%) did not have previously known AF. New AF was detected in 2.6% [95% confidence interval (CI) 2.2–3.0] of all participants without previous AF. In the high-risk group (n = 3766/6315, 59.6%), AF was diagnosed in 4.4% (95% CI 3.7–5.1) of the participants. Out of these, 18% had AF on their index-ECG. In the low-risk group, one participant was diagnosed with AF on index-ECG. The screening procedure resulted in an increase in known prevalence from 8.1% to 10.5% among participants. Oral anticoagulant treatment was initiated in 94.5% of the participants with newly diagnosed AF.

Conclusion

N-terminal B-type natriuretic peptide-stratified systematic screening for AF identified 4.4% of the high-risk participants with new AF. Oral anticoagulant treatment initiation was well accepted in the group diagnosed with new AF.

Large-scale screening studies for atrial fibrillation - is it worth the effort?

Atrial fibrillation (AF) is a common disease with increasing prevalence, approximately 3.2% in the adult population. In addition, about one third of AF cases are considered asymptomatic. Due to increased longevity, increased detection and increased prevalence of risk factors, the prevalence of AF is expected to at least double by the year 2060. Patients with AF have an increased risk for ischaemic stroke, heart failure, death and cognitive decline. Treatment with oral anticoagulation reduces the risk of ischaemic stroke and mortality, and the effect on cognitive decline is being studied. Based on the increasing prevalence of AF, its often asymptomatic and paroxysmal presentation and the efficacy of oral anticoagulation treatment, screening for AF has been proposed. AF seems to fulfil most of the Wilson-Jungner criteria for screening issued by the World Health Organization, but some knowledge gaps remain, gaps that will be addressed by several ongoing studies. The knowledge gaps in AF screening consist of the magnitude of the net benefit or net harm inflicted by AF screening because the oral anticoagulation treatment will also increase the risk of bleeding, and the psychological effects of AF screening are not very well studied. So far, the AF screening recommendations issued by the European Society of Cardiology have had limited impact on national and regional AF screening activities. Several large-scale AF screening studies will report results on hard endpoints within the next few years, and these results will hopefully manifest AF as a cardiovascular disease which we need to pay more attention to.

Risk markers of incident atrial fibrillation in patients with coronary heart disease

BACKGROUND

In patients with coronary heart disease (CHD), atrial fibrillation (AF) is associated with increased morbidity and mortality. We investigated the associations between clinical risk factors and biomarkers with incident AF in patients with CHD.

METHODS AND RESULTS

Around 13,153 patients with optimally treated CHD included in the STabilization of Atherosclerotic plaque By Initiation of darapLadIb TherapY (STABILITY) trial with plasma samples obtained at randomization. Mean follow-up time was 3.5 years. The association between clinical risk factors and biomarkers with incident AF was estimated with Cox-regression models. Validation was performed in 1,894 patients with non-ST-elevation acute coronary syndrome included in the FRISC-II trial. The median (min-max) age was 64 years (range 26-92) and 2,514 (19.1%) were women. A total of 541 patients, annual incidence rate of 1.2%, developed AF during follow-up. In multivariable models, older age, higher levels of NT-proBNP, higher body mass index (BMI), male sex, geographic regions, low physical activity, and heart failure were independently associated with increased risk of incident AF with hazard ratios ranging from 1.04 to 1.79 (P ≤ .05). NT-proBNP improved the C-index from 0.70 to 0.71. In the validation cohort, age, BMI, and NT-proBNP were associated with increased risk of incident AF with similar hazard ratios.

CONCLUSIONS

In patients with optimally treated CHD, the incidence of new AF was 1.2% per year. Age, NT-proBNP as a marker of impaired cardiac function, and BMI were the strongest factors, independently and consistently associated with incident AF. Male sex and low physical activity may also contribute to the risk of AF in patients with CHD.

Predictive Role of BNP/NT-proBNP in Non-Heart Failure Patients Undergoing Catheter Ablation for Atrial Fibrillation: An Updated Systematic Review

Atrial Fibrillation (AF) is a growing public health issue, associated with significant morbidity and mortality. In addition to pharmacological therapy, catheter ablation is an effective strategy in restoring and maintaining sinus rhythm. However, ablation is not without risk, and AF recurs in a significant proportion of patients. Non-invasive, easily accessible markers or indices that could stratify patients depending on the likelihood of a successful outcome following ablation would allow us to select the most appropriate patients for the procedure, reducing the AF recurrence rate and exposure to potentially life-threatening risks. There has been much attention paid to Brain Natriuretic Peptide (BNP) and N-Terminal prohormone of Brain Natriuretic Peptide (NT-proBNP) as possible predictive markers of successful ablation. Several studies have demonstrated an association between higher pre-ablation levels of these peptides, and a greater likelihood of AF recurrence. Therefore, there may be a role for measuring brain natriuretic peptides levels when selecting patients for catheter ablation.

Short-term associations between ambient air pollution and acute atrial fibrillation episodes

INTRODUCTION

Atrial fibrillation (AF), prevalent in approximately 1-3% of the population, is associated with a higher risk of stroke, dementia, mortality, and a reduced quality of life. Air pollution may be associated with heart rhythm disturbances, but there is limited evidence regarding whether short-term changes in air pollution levels are associated with acute onset of AF episodes.

METHODS

We screened 8,899 randomly selected 75-yearolds living in Stockholm without previously known AF for AF using home-based short-term ambulatory 1-lead ECG-measurements 2-4 times a day for 14 days. Screenings were carried out in 2012-2013 and 2016-2018. We used generalized estimating equations to quantify the association between PM_2.5, PM₁₀, NO₂ and O₃ obtained from a fixed monitoring station and risk of AF onset among participants with AF observed during the screening period, adjusting for temperature, relative humidity and temporal factors. We explored potential susceptible subgroups.

RESULTS

Among 218 participants with 469 AF episodes we observed higher odds of AF following higher 24-hour mean levels of PM₁₀ and O₃, reaching statistical significance for PM₁₀ levels averaged over the previous 12-24-hours [OR 1.10 (95%CI 1.01-1.19) per IQR of PM₁₀ (7.8 µg/m³)]. In subgroup analyses, PM_2.5 was more strongly associated with AF among participants with hypertension and PM₁₀ and O₃ were more strongly associated with AF among participants with diabetes and overweight.

CONCLUSION

These results suggest that in an urban setting with relatively low levels of ambient air pollution, hourly changes in pollutant levels may increase the risk of acute episodes of both asymptomatic and symptomatic AF, especially among people with diabetes, hypertension or overweight.

Atrial Tissue Pro-Fibrotic M2 Macrophage Marker CD163+, Gene Expression of Procollagen and B-Type Natriuretic Peptide

Background

Atrial tissue fibrosis is linked to inflammatory cells, yet is incompletely understood. A growing body of literature associates peripheral blood levels of the antifibrotic hormone BNP (B‐type natriuretic peptide) with atrial fibrillation (AF). We investigated the relationship between pro‐fibrotic tissue M2 macrophage marker Cluster of Differentiation (CD)163+, atrial procollagen expression, and BNP gene expression in patients with and without AF.

Methods and Results

In a cross‐sectional study design, right atrial tissue was procured from 37 consecutive, consenting, stable patients without heart failure or left ventricular systolic dysfunction, of whom 10 had AF and 27 were non‐AF controls. Samples were analyzed for BNP and fibro‐inflammatory gene expression, as well as fibrosis and CD163+. Primary analyses showed strong correlations (all P<0.008) between M2 macrophage CD163+ staining, procollagen gene expression, and myocardial BNP gene expression across the entire cohort. In secondary analyses without multiplicity adjustments, AF patients had greater left atrial volume index, more valve disease, higher serum BNP, and altered collagen turnover markers versus controls (all P<0.05). AF patients also showed higher atrial tissue M2 macrophage CD163+, collagen volume fraction, gene expression of procollagen 1 and 3, as well as reduced expression of the BNP clearance receptor NPRC (all P<0.05). Atrial procollagen 3 gene expression was correlated with fibrosis and BNP gene expression was correlated with serum BNP.

Conclusions

Elevated atrial tissue pro‐fibrotic M2 macrophage CD163+ is associated with increased myocardial gene expression of procollagen and anti‐fibrotic BNP and is higher in patients with AF. More work on modulation of BNP signaling for treatment and prevention of AF may be warranted.

Comprehensive Evaluation of Rhythm Monitoring Strategies in Screening for Atrial Fibrillation

Background:

Stroke is an increasing health problem worldwide. Atrial fibrillation (AF) is a major risk factor for stroke, and the attention given to AF screening is rising, as new monitoring technologies emerge. We aimed to evaluate the performance of a large panel of screening strategies and to assess population characteristics associated with diagnostic yield.

Methods:

Individuals with stroke risk factors but without AF were recruited from the general population to undergo screening with an implantable loop recorder. New-onset AF lasting ≥6 minutes was adjudicated by senior cardiologists. After continuous monitoring for >3 years, complete day-to-day heart rhythm data sets were reconstructed for every participant, including exact time of onset and termination of all AF episodes. Random sampling was applied to assess the sensitivity and negative predictive value of screening with various simulated screening strategies compared with the implantable loop recorder. The diagnostic yield across strategies and population subgroups was compared by use of nonparametric tests.

Results:

The rhythm data sets comprised 590 participants enduring a total of 659 758 days of continuous monitoring and 20 110 AF episodes. In these data, a single 10-second ECG yielded a sensitivity (and negative predictive value) of 1.5% (66%) for AF detection, increasing to 8.3% (67%) for twice-daily 30-second ECGs during 14 days and to 11% (68%), 13% (68%), 15% (69%), 21% (70%), and 34% (74%) for a single 24-hour, 48-hour, 72-hour, 7-day, or 30-day continuous monitoring, respectively. AF detection further improved when subsequent screenings were performed or when the same monitoring duration was spread over several periods compared with a single period (eg, three 24-hour monitorings versus one 72-hour monitoring; P <0.0001 for all comparisons). The sensitivity was consistently higher among participants with age ≥75 years, male sex, CHADS 2 score >2, or NT-proBNP (N-terminal pro-B-type natriuretic peptide) ≥40 pmol/L and among participants with underlying ≥24-hour AF episodes compared with shorter AF ( P <0.0001 for all screening strategies).

Conclusions:

In screening for AF among participants with stroke risk factors, the diagnostic yield increased with duration, dispersion, and number of screenings, although all strategies had low yield compared with the implantable loop recorder. The sensitivity was higher among participants who were older, were male, or had higher NT-proBNP.

Registration:

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02036450 .

Clinical and echocardiographic characteristics of individuals aged 75/76 years old with screening-detected elevated NT-proBNP levels

Background

High plasma levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) indicate increased probability of congestive heart failure (CHF) and atrial fibrillation (AF) and are associated with poor prognosis.

Objective

We aimed to describe the clinical and echocardiographic characteristics of a population of individuals aged 75/76 years old with NT-proBNP ≥900 ng/L without previously known CHF or AF.

Methods

All individuals aged 75/76 years in the Stockholm region were randomised to a screening study for AF. Half of them were invited to screening. Of those invited, 49.5% agreed to participate. Individuals with NT-proBNP ≥900 ng/L without known CHF were invited for further clinical evaluation.

Results

Among 6315 participants without AF who had NT-proBNP sampled, 102 without previously known CHF had ≥900 ng/L. Of these, 93 completed further clinical investigations. In the population that was clinically investigated, 53% were female, and the median NT-proBNP was 1200 ng/L. New AF was found in 28 (30%). The NT-proBNP value in this group was not significantly different from those where AF was not detected (median 1285 vs 1178 ng/L). Patients with newly detected AF had larger left atrial volume and higher pulmonary artery pressure than those without AF. Preserved left ventricular ejection fraction (≥50%) was found in 86% of the participants, mid-range ejection fraction (40%–49%) in 3.2% and reduced ejection fraction (<40%) in 10.8%. Thirteen patients (14%) had other serious cardiac disorders that required medical attention.

Conclusion

Elderly individuals with NT-proBNP levels ≥900 ng/L constitute a population at high cardiovascular risk even in the absence of diagnosed CHF or AF, and therefore merit further investigation.

N-Terminal Pro B-Type Natriuretic Peptide's Usefulness for Paroxysmal Atrial Fibrillation Detection Among Populations Carrying Cardiovascular Risk Factors

Background: Atrial fibrillation (AF) systematic screening studies have not shown a clear usefulness in stroke prevention, as AF might present as paroxysmal and asymptomatic. This study aims to determine the usefulness of some blood-biomarkers to identify paroxysmal atrial fibrillation in the context of a screening programme. Methods: A total of 100 subjects aged 65-75 years with hypertension and diabetes were randomly selected. AF was assessed by conventional electrocardiogram (ECG) and 4 weeks monitoring with a wearable Holter device (Nuubo™). N-terminal pro B-type natriuretic peptide (NT-proBNP), apolipoprotein CIII (ApoC-III), von Willebrand factor (vWF), ADAMTS13, urokinase plasminogen activator surface receptor (uPAR), and urokinase plasminogen activator (uPA) were determined in serum/plasma samples and the levels were compared depending on AF presence and mode of detection. Results: The AF prevalence in the studied population was found to be 20%. In seven subjects, AF was only detected after 1 month of Holter monitoring (hAF group). NT-proBNP levels were higher in subjects with AF compared with subjects with no AF (p < 0.0001), even when only taking into account the hAF group (p = 0.031). No significant differences were found in the other biomarkers. The NT-proBNP >95 pg/ml cut-off showed high sensitivity and specificity to detect AF (95%, 66.2%) or hAF (85.72%, 66.2%) and was found to be an independent predictor of AF and hAF in a logistic regression analysis. NT-proBNP correlated with AF burden (r = 0.597, p = 0.024). Conclusion: NT-proBNP was elevated in AF cases not identified by ECG; thus, it may be used as a screening biomarker in asymptomatic high-risk populations, with a promising cut-off point of 95 pg/ml that requires further validation.

MediYoga as a part of a self-management programme among patients with paroxysmal atrial fibrillation - a randomised study

BACKGROUND

Paroxysmal atrial fibrillation is associated with impaired health-related quality of life. Yoga has been suggested to improve health-related quality of life among patients with heart failure and hypertension.

AIM

The aim of the study was to evaluate the effects of MediYoga, in respect of health-related quality of life, blood pressure, heart rate, as well as N-terminal pro b-type natriuretic peptide, among patients with symptomatic paroxysmal atrial fibrillation, compared with standard therapy or relaxation.

METHODS

Patients with symptomatic paroxysmal atrial fibrillation, n=132, were stratified for gender and randomised to MediYoga, a relaxation group or a control group, 44 patients per group with a 12-week follow-up. Health-related quality of life, blood pressure, heart rate and N-terminal pro b-type natriuretic peptide were assessed.

RESULTS

After 12 weeks, there were no differences in health-related quality of life between the groups. There were improvements in Short-Form Health Survey bodily pain, general health, social function, mental health and mental component summary scores within the MediYoga group (p=0.014, p=0.037, p=0.029, p=0.030, p=0.019, respectively). No change was seen in the relaxation and control groups. Systolic blood pressure decreased in the MediYoga group (134±18 to 127±13) compared with the control group (126±17 to 127±15, p=0.041); no difference compared with the relaxation group (131±17 to 125±12). Diastolic blood pressure decreased in the MediYoga group (79±9 to 74 ±9) compared with the control group (76±9 to 79±8, p=0.005); no difference compared with the relaxation group (76±9 to 77±8). There were no differences in heart rate and N-terminal pro b-type natriuretic peptide between the groups after 12 weeks.

CONCLUSIONS

MediYoga improves health-related quality of life and decreases blood pressure in patients with paroxysmal atrial fibrillation. MediYoga may be used as a part of a self-management programme among patients with paroxysmal atrial fibrillation.

Assessment of N-terminal pro-B-type natriuretic peptide level in screening for atrial fibrillation in primary health care

Background

Atrial fibrillation (AF), an important cause of thromboembolic events, is often silent and intermittent, thus presenting a diagnostic challenge. The aim of this study was to assess whether the plasma level of N-terminal pro-brain natriuretic peptide (NT-proBNP) is related to the presence of AF and thereby might be used to facilitate screening programs for AF in primary care.

Methods

This was a cross sectional screening study. A population of 70–74-year-old individuals registered at a single primary care center in Stockholm were invited to AF screening. Intermittent ECG recording, 30 seconds twice a day using a hand-held device over 2 weeks, was offered to participants without previously known AF. Of the 324 participating persons, 34 patients had already known AF and 16 new cases of AF were detected by screening. Plasma NT-proBNP was measured in patients with previously known AF, newly detected AF, and 53 control participants without AF.

Findings

The median NT-proBNP was 697 ng/L in patients with previously known AF, 335 ng/L in new cases of AF, and 146 ng/L in patients without AF. After adjustment for several clinical variables and morbidities, the differences of median NT-proBNP levels were statistically significant between cases of previously known AF and new cases of AF as well as between new cases of AF and those without AF. The area under receiver operating characteristic curve of detection of new AF was 0.68 (95% CI 0.56 to 0.79) yielding a cut-off point of 124 ng/L with 75% sensitivity, 45% specificity, and 86% negative predictive value.

Conclusions

The NT-proBNP plasma levels among patients with known AF are higher than those with newly detected AF, and the latter have higher levels than those without AF. Therefore NT-proBNP might be a useful screening marker for the detection of AF and its persistence.

The Biomarkers NT-proBNP and CA-125 are Elevated in Patients with Idiopathic Atrial Fibrillation

BACKGROUND

Blood biomarkers related to AF could be useful to detect silent AF and to develop stratified strategies for AF prevention. Previous studies identified markers that predict incident AF. However, it is difficult to differentiate whether biomarkers relate to underlying cardiovascular diseases, are generated by the atria in response to an AF episode, or both. We therefore measured a panel of blood biomarkers in patients without overt CVD with and without AF to investigate the association between biomarkers and atrial fibrillation (AF) in patients without overt cardiovascular disease (CVD).

METHODS

Blood samples - drawn remote from an AF episode - of 60 patients with AF but without overt forms of CVD (idiopathic AF; iAF) were compared to 120 matched patients with sinus rhythm only. A novel antibody-based method for quantification of blood biomarkers (OlinkProseek Multiplex Cardiovascular) was used to compare 92 biomarkers between the two groups.

RESULTS

N-terminal pro-B-type natriuretic peptide (NT-proBNP), Cathepsin L1, Endothelial cell-specific molecule 1, Cancer Antigen-125 (CA-125), Heat shock 27kDa protein, Galanin peptides, Proteinase-activated receptor 1, Stem cell factor, and CD40-ligand were all higher in iAF patients than in SR controls. Both NT-proBNP (OR1.55(1.07-2.25);p=0.022) and CA-125 (OR1.68(1.07-2.64);p=0.026) were independently associated with iAF.

CONCLUSIONS

This exploratory study, investigating over 90 cardiovascular blood biomarkers in patients without known CVD, identified one established biomarker for paroxysmal AF, NT-proBNP, and a novel marker, CA-125. CA-125 - previously unrelated to paroxysmal AF in an otherwise healthy population - may thus be a potential indicator of remote paroxysms of AF.