The 2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society Comprehensive Guidelines for the Management of Atrial Fibrillation

Atrial thrombus detection on transoesophageal echocardiography in patients with atrial fibrillation undergoing cardioversion or catheter ablation: A pooled analysis of rates and predictors

OBJECTIVE

To summarize data on the rates and predictors of left atrial thrombus/left atrial appendage thrombus (LAT/LAAT) detection by transoesophageal echocardiography (TEE) before electrical cardioversion (ECV) or catheter ablation (CA) for atrial fibrillation (AF).

METHODS

EMBASE, MEDLINE, and Web of Science Core Collection were searched to identify all studies providing relevant data and published by October 7, 2020. A random-effects meta-analysis method was used to pool effect size estimates.

RESULTS

A total of 85 studies were included, reporting data from 56 660 patients with AF. In patients undergoing CA and ECV, the pooled prevalence of LAT/LAAT was 1.8% and 7.5% in those not on oral anticoagulation (OAC), 1.8% and 5.5% in those taking OAC, and 1.3% and 4.9% in case of adequate OAC, respectively. According to the type of OAC, the prevalence was 2.0% and 7.6% for vitamin K antagonist, 1.3% and 3.5% for direct oral anticoagulant. Predictors of LAT/LAAT detection were nonparoxysmal AF (odds ratio [OR]: 3.6, 95% confidence interval: 2.4-5.2), hypertension (OR: 2.9, 1.2-7.0), previous stroke (OR: 3.0, 1.6-5.63), heart failure (OR: 4.3, 2.7-6.8), and CHADS₂ score ≥2 (OR: 3.3, 1.9-5.8) for patients undergoing CA; and heart failure (OR: 2.8, 1.3-6.2) and the CHA₂ DS₂ -VASc score (OR: 2.55, 1.5-4.5) for those undergoing ECV.

CONCLUSION

The prevalence of LAT/LAAT in AF patients undergoing ECV or CA varies widely, mainly due to differences in patient risk profiles and OAC types. Further research should determine whether the predictors of LAT/LAAT detection identified by this study could be used to select patients who require preprocedural TEE.

Dose specific effectiveness and safety of DOACs in patients with non-valvular atrial fibrillation: A Canadian retrospective cohort study

BACKGROUND

Direct oral anticoagulants (DOACs) have been proven to be effective and safe for prevention of ischemic stroke and systemic embolism in patients with non-valvular atrial fibrillation (NVAF). However, suboptimal adherence, variable dosing and use in patient populations that otherwise would have been excluded from clinical trials may impact the efficacy and safety profile of DOACs in a routine care setting. We compared stroke, bleeding, and mortality rates on and off therapy for standard and low-dose DOACs (apixaban, rivaroxaban, dabigatran) versus warfarin in a Canadian cohort. We also assessed persistence of DOACs compared to warfarin.

METHODS

We conducted six 1-1 propensity-score matched retrospective cohort analyses using Quebec health administrative databases (2011-2017). NVAF patients (≥18 years) covered by the public medication insurance plan entered the cohort on the first OAC dispensation date. We excluded those with OAC use in the previous year or stroke or bleeding diagnoses in the previous two years. Follow-up ended at death, March 2017 or end of medication coverage by the public plan. Time-dependent Cox regression was applied.

RESULTS

We evaluated 10,893 patients initiated on apixaban (7206 standard, 3687 low-dose), 10,190 on rivaroxaban (7396 standard, 2794 low-dose), 5884 on dabigatran (2756 standard, 3128 low-dose), and propensity score-matched warfarin users. Across standard-dose DOACs, compared to warfarin, stroke risks were similar; bleeding risks were lower with apixaban (hazard ratio 0.63; 95% confidence interval 0.52-0.77) and dabigatran (0.47; 0.35-0.64) but not rivaroxaban (0.93; 0.79-1.10); death risks were lower with all DOACs. For low-dose DOACs, rivaroxaban demonstrated higher stroke (1.79; 1.21-2.64) and bleeding risks (1.37; 1.09-1.73); other agents had stroke risks similar to warfarin and bleeding risks lower than warfarin; only low-dose dabigatran had lower death risk (0.59; 0.52-0.68). Treatment discontinuation was lower with DOACs versus warfarin with the exception of low-dose rivaroxaban. The risks of stroke were 2-4 folds higher during time off any OAC versus time on warfarin. The risks of death were higher, while the risks of bleeding were generally lower during times off any OAC.

CONCLUSIONS

Standard-dose DOACs had similar stroke, better persistence and mortality profiles than warfarin. Only standard dose apixaban and dabigatran had better bleeding profiles than warfarin. Low-dose rivaroxaban had worse persistence, stroke and bleeding profiles than warfarin, while low-dose apixaban and dabigatran had similar stroke and better bleeding profiles. Real-world use of DOACs may explain some of the differences observed in Canadian routine care versus the phase III clinical trials.

Initiation of anticoagulation in atrial fibrillation by primary care physicians: Results of a telephone survey

BACKGROUND

Direct oral anticoagulants (DOACs) are prescribed for over 80% of patients who start anticoagulant therapy for a new diagnosis of atrial fibrillation (AF). Inappropriate DOAC prescriptions are associated with increased mortality. However, limited data exist as to what proportion of primary care physicians (PCPs) initiate anticoagulation in patients with new AF and the extent of their DOAC knowledge.

MATERIAL AND METHODS

We conducted a telephone survey of randomly selected PCPs in Ontario, Canada. Our primary objective was to determine the percentage of PCPs who initiate anticoagulation in new AF patients and the proportion of patients they initiate on DOACs. Our secondary objectives were to assess PCPs' knowledge about DOACs and to identify educational opportunities to address any knowledge gaps.

RESULTS

Our survey included 50 respondents. After making a new AF diagnosis, 66% of PCPs stated that they usually initiate anticoagulation themselves and 84% prescribed a DOAC at least 75% of the time. Potential DOAC knowledge gaps included: administration considerations, off-label dosing, concomitant use of acetylsalicylic acid (ASA) in stable coronary artery disease (CAD) and use in valvular AF.

CONCLUSION

Most PCPs initiate anticoagulants for AF and prescribe DOACs for the vast majority of new patients. PCPs were well versed in certain aspects of DOAC prescribing, however, a number of knowledge gaps were identified. PCPs may benefit from targeted education in these areas to improve patient outcomes in AF.

Antithrombotic Management in Ischemic Stroke with Essential Thrombocythemia: Current Evidence and Dilemmas

Thrombotic diseases like ischemic stroke are common complications of essential thrombocythemia (ET) due to abnormal megakaryopoiesis and platelet dysfunction. Ischemic stroke in ET can occur as a result of both cerebral arterial and venous thrombosis. Management of ET is aimed at preventing vascular complications including thrombosis. Acute management of ischemic stroke in ET is the same as that in the general population without myeloproliferative disorders. However, an ET patient with ischemic stroke is at high risk for rethrombosis and is therefore additionally managed with cytoreductive therapy and antithrombotic agents. Given abnormal platelet production in ET, there is suboptimal suppression of platelets with the standard recommended dose of aspirin for cardiovascular (CV) prevention. Hence, for optimal CV protection in ET, low-dose aspirin is recommended twice daily in an arterial thrombotic disease like atherothrombotic ischemic stroke in presence of the following risk factors: age >60 years, Janus kinase2 V617F gene mutation, and presence of CV risk factors. In the presence of the same risk factors, concurrent antiplatelet and anticoagulant therapy is suggested for venous thrombosis. However, increased risk of bleeding with dual antithrombotic agents poses a significant challenge in their use in cerebral venous thromboembolism or atrial fibrillation in presence of the above-mentioned risk factors. We discuss these dilemmas regarding antithrombotic management in ischemic stroke in ET in this case-based review of literature in the light of current evidence.

Catheter Ablation of Atrial Fibrillation in Heart Failure: from Evidences to Guidelines

PURPOSE OF REVIEW

Catheter ablation of atrial fibrillation in heart failure seems to be the way to improve the quality of life, life expectance, and prognosis. In this review, we outline the growing role of this therapy and which patients can benefit from it.

RECENT FINDINGS

While previous studies comparing rate control and rhythm control had not demonstrated the superiority of rhythm control in the prognosis of patients with atrial fibrillation and heart failure, recent findings seem to demonstrate that catheter ablation of atrial fibrillation reduces mortality and hospitalization for heart failure and improves the quality of life, when compared to medical therapy alone. An early rhythm-control strategy in atrial fibrillation may reduce cardiovascular death, stroke, hospitalization for HF, or acute coronary syndrome. Catheter ablation in heart failure is an effective and safe solution to obtain a rhythm control and, therefore, to improve outcomes. A better selection of the patients could help to avoid futile procedures and to identify patients requiring a closer follow-up, to redo procedures, or the addition of antiarrhythmic drugs.

Safety and Efficacy of Non-Vitamin K Oral Anticoagulant Use Early After Cardiac Surgery: A Systematic Review

OBJECTIVE

To determine the safety and efficacy of non-vitamin K oral anticoagulants (NOACs) initiated early after cardiac surgery.

DATA SOURCES:

Cochrane Central Register of Controlled Trials, EMBASE, and MEDLINE (database inception to January 20, 2021), www.clinicaltrials.gov, www.who.int/ictrp/search/en/, NOAC trial registries, and bibliographies of relevant guidelines and other reviews were used.

STUDY SELECTION AND DATA EXTRACTION

Observational studies and randomized controlled trials (RCTs) that initiated NOACs within the index hospitalization and that reported bleeding for the primary outcome were included.

DATA SYNTHESIS

A total of 6 cohort studies, 1 RCT, and 3 ongoing RCTs were included. Most studies were single-centered, limited to postoperative atrial fibrillation after coronary artery bypass grafting, and with 30-day follow-up; few studies included patients with isolated bioprosthetic valve replacement or valve repair. Bleeding risk varied (0%-28.6%), and all but one study showed no significantly higher risk with NOAC compared with warfarin.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Overall, NOACs were used in 26% to 37.5% of patients early after cardiac surgery. Starting a NOAC on postoperative day 4 appeared to have similar bleeding rates compared with warfarin, but clinical application is limited by heterogeneity of outcome definitions, confounding, and bias. Compared with warfarin, NOACs may have similar thromboembolism risk, reduced length of stay, and cost.

CONCLUSIONS

There is limited evidence to guide NOAC use early after cardiac surgery. Three ongoing randomized trials will add to the literature and provide guidance for clinicians on whether, in whom, when, and how to use NOACs safely early after cardiac surgery.

Lenient rate control versus strict rate control for atrial fibrillation: a protocol for the Danish Atrial Fibrillation (DanAF) randomised clinical trial

INTRODUCTION

Atrial fibrillation is the most common heart arrhythmia with a prevalence of approximately 2% in the western world. Atrial fibrillation is associated with an increased risk of death and morbidity. In many patients, a rate control strategy is recommended. The optimal heart rate target is disputed despite the results of the the RAte Control Efficacy in permanent atrial fibrillation: a comparison between lenient vs strict rate control II (RACE II) trial.Our primary objective will be to investigate the effect of lenient rate control strategy (<110 beats per minute (bpm) at rest) compared with strict rate control strategy (<80 bpm at rest) on quality of life in patients with persistent or permanent atrial fibrillation.

METHODS AND ANALYSIS

We plan a two-group, superiority randomised clinical trial. 350 outpatients with persistent or permanent atrial fibrillation will be recruited from four hospitals, across three regions in Denmark. Participants will be randomised 1:1 to a lenient medical rate control strategy (<110 bpm at rest) or a strict medical rate control strategy (<80 bpm at rest). The recruitment phase is planned to be 2 years with 3 years of follow-up. Recruitment is expected to start in January 2021. The primary outcome will be quality of life using the Short Form-36 (SF-36) questionnaire (physical component score). Secondary outcomes will be days alive outside hospital, symptom control using the Atrial Fibrillation Effect on Quality of Life, quality of life using the SF-36 questionnaire (mental component score) and serious adverse events. The primary assessment time point for all outcomes will be 1 year after randomisation.

ETHICS AND DISSEMINATION

Ethics approval was obtained through the ethics committee in Region Zealand. The design and findings will be published in peer-reviewed journals as well as be made available on ClinicalTrials.gov.

TRIAL REGISTRATION NUMBER

NCT04542785.

Why translation from basic discoveries to clinical applications is so difficult for atrial fibrillation and possible approaches to improving it

Atrial fibrillation (AF) is the most common sustained clinical arrhythmia, with a lifetime incidence of up to 37%, and is a major contributor to population morbidity and mortality. Important components of AF management include control of cardiac rhythm, rate, and thromboembolic risk. In this narrative review article, we focus on rhythm-control therapy. The available therapies for cardiac rhythm control include antiarrhythmic drugs and catheter-based ablation procedures; both of these are presently neither optimally effective nor safe. In order to develop improved treatment options, it is necessary to use preclinical models, both to identify novel mechanism-based therapeutic targets and to test the effects of putative therapies before initiating clinical trials. Extensive research over the past 30 years has provided many insights into AF mechanisms that can be used to design new rhythm-maintenance approaches. However, it has proven very difficult to translate these mechanistic discoveries into clinically applicable safe and effective new therapies. The aim of this article is to explore the challenges that underlie this phenomenon. We begin by considering the basic problem of AF, including its clinical importance, the current therapeutic landscape, the drug development pipeline, and the notion of upstream therapy. We then discuss the currently available preclinical models of AF and their limitations, and move on to regulatory hurdles and considerations and then review industry concerns and strategies. Finally, we evaluate potential paths forward, attempting to derive insights from the developmental history of currently used approaches and suggesting possible paths for the future. While the introduction of successful conceptually innovative new treatments for AF control is proving extremely difficult, one significant breakthrough is likely to revolutionize both AF management and the therapeutic development landscape.

New aspects of endocrine control of atrial fibrillation and possibilities for clinical translation

Hormones are potent endo-, para-, and autocrine endogenous regulators of the function of multiple organs, including the heart. Endocrine dysfunction promotes a number of cardiovascular diseases, including atrial fibrillation (AF). While the heart is a target for endocrine regulation, it is also an active endocrine organ itself, secreting a number of important bioactive hormones that convey significant endocrine effects, but also through para-/autocrine actions, actively participate in cardiac self-regulation. The hormones regulating heart-function work in concert to support myocardial performance. AF is a serious clinical problem associated with increased morbidity and mortality, mainly due to stroke and heart failure. Current therapies for AF remain inadequate. AF is characterized by altered atrial function and structure, including electrical and profibrotic remodelling in the atria and ventricles, which facilitates AF progression and hampers its treatment. Although features of this remodelling are well-established and its mechanisms are partly understood, important pathways pertinent to AF arrhythmogenesis are still unidentified. The discovery of these missing pathways has the potential to lead to therapeutic breakthroughs. Endocrine dysfunction is well-recognized to lead to AF. In this review, we discuss endocrine and cardiocrine signalling systems that directly, or as a consequence of an underlying cardiac pathology, contribute to AF pathogenesis. More specifically, we consider the roles of products from the hypothalamic-pituitary axis, the adrenal glands, adipose tissue, the renin–angiotensin system, atrial cardiomyocytes, and the thyroid gland in controlling atrial electrical and structural properties. The influence of endocrine/paracrine dysfunction on AF risk and mechanisms is evaluated and discussed. We focus on the most recent findings and reflect on the potential of translating them into clinical application.

Evaluating Polygenic Risk Scores in "Lone" Atrial Fibrillation

Background

Polygenic scores incorporating varying numbers of single nucleotide polymorphisms (SNPs) have been demonstrated to exert a prominent role in atrial fibrillation (AF). We sought to compare the relative discriminatory capacities of 2 previously validated polygenic scores in "lone" AF.

Methods

A total of 186 lone AF cases of European ancestry underwent SNP genotyping. A genome-wide polygenic score (GPS) and polygenic risk score (PRS) involving 6,730,541 and 1168 SNPs, respectively, were calculated for 186 cases and 423 controls of European ancestry from the 1000 Genomes (1KG) Project. The distribution of the polygenic scores was compared between the cases and controls and their discriminatory capacities were evaluated using receiver operating characteristic (ROC) curves.

Results

A total of 34.4% of patients with lone AF had GPS scores greater than the top 10th percentile of 1KG controls, corresponding to a 4.64-fold increased odds (95% confidence interval [CI], 2.99-7.18; P < 0.001) for AF. A PRS score in the top 10th percentile of 1KG controls was observed in 26.3% of cases, which equated to a 3.16-fold increased odds (95% CI, 2.01-4.98; P < 0.001) for AF. Comparison of C-statistics from ROC curves indicated improved discriminatory capacity of the GPS (0.76) relative to the PRS (0.70) (P = 0.002).

Conclusions

Our study evaluating 2 polygenic scores for AF suggests that the GPS, containing more than 6.7 million SNPs, exhibits an improved discriminatory capacity in lone AF compared with a PRS possessing 1168 SNPs. Our findings suggest that genetic risk scores for AF that maximally leverage genomic data may provide improved predictive power.

Cryoablation or Drug Therapy for Initial Treatment of Atrial Fibrillation

BACKGROUND

Guidelines recommend a trial of one or more antiarrhythmic drugs before catheter ablation is considered in patients with atrial fibrillation. However, first-line ablation may be more effective in maintaining sinus rhythm.

METHODS

We randomly assigned 303 patients with symptomatic, paroxysmal, untreated atrial fibrillation to undergo catheter ablation with a cryothermy balloon or to receive antiarrhythmic drug therapy for initial rhythm control. All the patients received an implantable cardiac monitoring device to detect atrial tachyarrhythmia. The follow-up period was 12 months. The primary end point was the first documented recurrence of any atrial tachyarrhythmia (atrial fibrillation, atrial flutter, or atrial tachycardia) between 91 and 365 days after catheter ablation or the initiation of an antiarrhythmic drug. The secondary end points included freedom from symptomatic arrhythmia, the atrial fibrillation burden, and quality of life.

RESULTS

At 1 year, a recurrence of atrial tachyarrhythmia had occurred in 66 of 154 patients (42.9%) assigned to undergo ablation and in 101 of 149 patients (67.8%) assigned to receive antiarrhythmic drugs (hazard ratio, 0.48; 95% confidence interval [CI], 0.35 to 0.66; P<0.001). Symptomatic atrial tachyarrhythmia had recurred in 11.0% of the patients who underwent ablation and in 26.2% of those who received antiarrhythmic drugs (hazard ratio, 0.39; 95% CI, 0.22 to 0.68). The median percentage of time in atrial fibrillation was 0% (interquartile range, 0 to 0.08) with ablation and 0.13% (interquartile range, 0 to 1.60) with antiarrhythmic drugs. Serious adverse events occurred in 5 patients (3.2%) who underwent ablation and in 6 patients (4.0%) who received antiarrhythmic drugs.

CONCLUSIONS

Among patients receiving initial treatment for symptomatic, paroxysmal atrial fibrillation, there was a significantly lower rate of atrial fibrillation recurrence with catheter cryoballoon ablation than with antiarrhythmic drug therapy, as assessed by continuous cardiac rhythm monitoring. (Funded by the Cardiac Arrhythmia Network of Canada and others; EARLY-AF ClinicalTrials.gov number, NCT02825979.).

Integrative Identification of Hub Genes Associated With Immune Cells in Atrial Fibrillation Using Weighted Gene Correlation Network Analysis

Background: Atrial fibrillation (AF) is the most common tachyarrhythmia in the clinic, leading to high morbidity and mortality. Although many studies on AF have been conducted, the molecular mechanism of AF has not been fully elucidated. This study was designed to explore the molecular mechanism of AF using integrative bioinformatics analysis and provide new insights into the pathophysiology of AF. Methods: The GSE115574 dataset was downloaded, and Cibersort was applied to estimate the relative expression of 22 kinds of immune cells. Differentially expressed genes (DEGs) were identified through the limma package in R language. Weighted gene correlation network analysis (WGCNA) was performed to cluster DEGs into different modules and explore relationships between modules and immune cell types. Functional enrichment analysis was performed on DEGs in the significant module, and hub genes were identified based on the protein-protein interaction (PPI) network. Hub genes were then verified using quantitative real-time polymerase chain reaction (qRT-PCR). Results: A total of 2,350 DEGs were identified and clustered into eleven modules using WGCNA. The magenta module with 246 genes was identified as the key module associated with M1 macrophages with the highest correlation coefficient. Three hub genes (CTSS, CSF2RB, and NCF2) were identified. The results verified using three other datasets and qRT-PCR demonstrated that the expression levels of these three genes in patients with AF were significantly higher than those in patients with SR, which were consistent with the bioinformatic analysis. Conclusion: Three novel genes identified using comprehensive bioinformatics analysis may play crucial roles in the pathophysiological mechanism in AF, which provide potential therapeutic targets and new insights into the treatment and early detection of AF.