Mechanisms of atrial structural changes caused by stretch occurring before and during early atrial fibrillation

Characterization of remodeling processes in the atria of atrioventricular block dogs: Utility as an early-stage atrial fibrillation model

To characterize utility of atrioventricular block (AVB) dogs as atrial fibrillation (AF) model, we studied remodeling processes occurring in their atria in acute (<2 weeks) and chronic (>4 weeks) phases. Fifty beagle dogs were used. Holter electrocardiogram demonstrated that paroxysmal AF occurred immediately after the production of AVB, of which duration tended to be prolonged in chronic phase. Electrophysiological analysis showed that inter-atrial conduction time and duration of burst pacing-induced AF increased in the chronic phase compared with those in the acute phase, but that atrial effective refractory period was hardly altered. Echocardiographic study revealed that diameters of left atrium, right pulmonary vein and inferior vena cava increased similarly in the acute and chronic phases. Histological evaluation indicated that hypertrophy and fibrosis in atrial tissue increased in the chronic phase. Electropharmacological characterization showed that i.v. pilsicainide effectively suppressed burst pacing-induced AF with increasing atrial conduction time and refractoriness of AVB dogs in chronic phase, but that i.v. amiodarone did not exert such electrophysiological effects. Taken together, AVB dogs in chronic phase appear to possess such pathophysiology as developed in the atria of early-stage AF patients, and therefore they can be used to evaluate drug candidates against early-stage AF.

Association of central arterial stiffness with atrial myopathy: the Atherosclerosis Risk in Communities (ARIC) study

Atrial myopathy-defined as abnormal left atrial (LA) size and function-is associated with an increased risk of atrial fibrillation, heart failure, and dementia. Central arterial stiffness is associated with increased atrial afterload and fibrosis and may be a risk factor for atrial myopathy. We examined the association of carotid-femoral pulse wave velocity (cfPWV) with LA function and assessed potential causal relationships. We included 2825 Atherosclerosis Risk in Communities (ARIC) study participants from Visit 5 (2011-2013). cfPWV was related to echocardiographic LA function continuously per 1-SD and categorically in quartiles. Mendelian randomization (MR) analysis was performed using U.K. Biobank-derived genetic variants associated with arterial stiffness index and cardiac magnetic resonance measures of LA function. When analyzed per SD increment (297.6 cm/s), higher cfPWV was significantly associated with lower LA reservoir and conduit strain (β = -0.53%, 95% CI [-0.81, -0.25] and β = -0.46%, 95% CI [-0.68, -0.25], respectively) after adjusting for demographics, clinical characteristics, systolic blood pressure, and left ventricular (LV) morphology and function. In MR analyses there was a non-significant inverse association of arterial stiffness index with LA total, passive, and active emptying fractions. Higher cfPWV is associated with lower LA reservoir and conduit strain, independent of systolic blood pressure and LV morphology and function. No evidence for a causal relationship between arterial stiffness index and alterations in LA function was found. Future studies should examine the prospective association of central arterial stiffness with LA function alterations.

Mechanisms of stretch-induced electro-anatomical remodeling and atrial arrhythmogenesis

Atrial fibrillation (AF) is the most common cardiac rhythm disorder, often occurring in the setting of atrial distension and elevated myocardialstretch. While various mechano-electrochemical signal transduction pathways have been linked to AF development and progression, the underlying molecular mechanisms remain poorly understood, hampering AF therapies. In this review, we describe different aspects of stretch-induced electro-anatomical remodeling as seen in animal models and in patients with AF. Specifically, we focus on cellular and molecular mechanisms that are responsible for mechano-electrochemical signal transduction and the development of ectopic beats triggering AF from pulmonary veins, the most common source of paroxysmal AF. Furthermore, we describe structural changes caused by stretch occurring before and shortly after the onset of AF as well as during AF progression, contributing to longstanding forms of AF. We also propose mechanical stretch as a new dimension to the concept "AF begets AF", in addition to underlying diseases. Finally, we discuss the mechanisms of these electro-anatomical alterations in a search for potential therapeutic strategies and the development of novel antiarrhythmic drugs targeted at the components of mechano-electrochemical signal transduction not only in cardiac myocytes, but also in cardiac non-myocyte cells.

Deciphering mechanisms of cardiomyocytes and non-cardiomyocyte transformation in myocardial remodeling of permanent atrial fibrillation

INTRODUCTION

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia, and it significantly increases the risk of cardiovascular complications and morbidity, even with appropriate treatment. Tissue remodeling has been a significant topic, while its systematic transcriptional signature remains unclear in AF.

OBJECTIVES

Our study aims to systematically investigate the molecular characteristics of AF at the cellular-level.

METHODS

We conducted single-nuclei RNA-sequencig (snRNA-seq) analysis using nuclei isolated from the left atrial appendage (LAA) of AF patients and sinus rhythm. Pathological staining was performed to validate the key findings of snRNA-seq.

RESULTS

A total of 30 cell subtypes were identified among 80, 592 nuclei. Within the LAA of AF, we observed a specific subtype of dedifferentiated cardiomyocytes (CMs) characterized by reduced expression of cardiac contractile proteins (TTN and TRDN) and heightened expression of extracellular-matrix related genes (COL1A2 and FBN1). Transcription factor prediction analysis revealed that gene expression patterns in dedifferentiated CMs were primarily regulated by CEBPG and GISLI. Additionally, we identified a distinct subtype of endothelial progenitor cells (EPCs) demonstrating elevated expression of PROM1 and KDR, a population decreased within the LAA of AF. Epicardial adipocytes disclosed a reduced release of the anti-inflammatory and anti-fibrotic factor PRG4, and an augmented secretion of VEGF signals targeting CMs. Additionally, we noted accumulation of M2-like macrophages and CD8+ T cells with high pro-inflammatory score in LAA of AF. Furthermore, the analysis of intercellular communication revealed specific pathways related to AF, such as inflammation, extracellular matrix, and vascular remodeling signals.

CONCLUSIONS

This study has discovered the presence of dedifferentiated CMs, a decrease in endothelial progenitor cells, a shift in the secretion profile of adipocytes, and an amplified inflammatory response in AF. These findings could offer crucial insights for future research on AF and serve as valuable references for investigating novel therapeutic approaches for AF.

2023 Cardiac Society of Australia and New Zealand Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation

Catheter ablation for atrial fibrillation (AF) has increased exponentially in many developed countries, including Australia and New Zealand. This Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation from the Cardiac Society of Australia and New Zealand (CSANZ) recognises healthcare factors, expertise and expenditure relevant to the Australian and New Zealand healthcare environments including considerations of potential implications for First Nations Peoples. The statement is cognisant of international advice but tailored to local conditions and populations, and is intended to be used by electrophysiologists, cardiologists and general physicians across all disciplines caring for patients with AF. They are also intended to provide guidance to healthcare facilities seeking to establish or maintain catheter ablation for AF.

Administration of USP7 inhibitor p22077 alleviates Angiotensin II (Ang II)-induced atrial fibrillation in Mice

Atrial fibrillation (AF), the most common cardiac arrhythmia, is an important contributor to mortality and morbidity. Ubquitin-specific protease 7 (USP7), one of the most abundant ubiquitin-specific proteases (USP), participated in many cellular events, such as cell proliferation, apoptosis, and tumourigenesis. However, its role in AF remains unknown. Here, the mice were treated with Ang II infusion to induce the AF model. Echocardiography was used to measure the atrial diameter. Electrical stimulation was programmed to measure the induction and duration of AF. The changes in atrial remodeling were measured using routine histologic analysis. Here, a significant increase in USP7 expression was observed in Ang II-stimulated atrial cardiomyocytes and atrial tissues, as well as in atrial tissues from patients with AF. The administration of p22077, the inhibitor of USP7, attenuated Ang II-induced inducibility and duration of AF, atrial dilatation, connexin dysfunction, atrial fibrosis, atrial inflammation, and atrial oxidase stress, and then inhibited the progression of AF. Mechanistically, the administration of p22077 alleviated Ang II-induced activation of TGF-β/Smad2, NF-κB/NLRP3, NADPH oxidases (NOX2 and NOX4) signals, the up-regulation of CX43, ox-CaMKII, CaMKII, Kir2.1, and down-regulation of SERCA2a. Together, this study, for the first time, suggests that USP7 is a critical driver of AF and revealing USP7 may present a new target for atrial fibrillation therapeutic strategies.

Synergistic Effects of Weight Loss and Catheter Ablation: Can microRNAs Serve as Predictive Biomarkers for the Prevention of Atrial Fibrillation Recurrence?

In atrial fibrillation (AF), multifactorial pathologic atrial alterations are manifested by structural and electrophysiological changes known as atrial remodeling. AF frequently develops in the context of underlying cardiac abnormalities. A critical mechanistic role played by atrial stretch is played by abnormal substrates in a number of conditions that predispose to AF, including obesity, heart failure, hypertension, and sleep apnea. The significant role of overweight and obesity in the development of AF is known; however, the differential effect of overweight, obesity, cardiovascular comorbidities, lifestyle, and other modifiable risk factors on the occurrence and recurrence of AF remains to be determined. Reverse remodeling of the atrial substrate and subsequent reduction in the AF burden by conversion into a typical sinus rhythm has been associated with weight loss through lifestyle changes or surgery. This makes it an essential pillar in the management of AF in obese patients. According to recently published research, microRNAs (miRs) may function as post-transcriptional regulators of genes involved in atrial remodeling, potentially contributing to the pathophysiology of AF. The focus of this review is on their modulation by both weight loss and catheter ablation interventions to counteract atrial remodeling in AF. Our analysis outlines the experimental and clinical evidence supporting the synergistic effects of weight loss and catheter ablation (CA) in reversing atrial electrical and structural remodeling in AF onset and in recurrent post-ablation AF by attenuating pro-thrombotic, pro-inflammatory, pro-fibrotic, arrhythmogenic, and male-sex-associated hypertrophic remodeling pathways. Furthermore, we discuss the promising role of miRs with prognostic potential as predictive biomarkers in guiding approaches to AF recurrence prevention.

Cardiac power output is associated with adverse outcomes in patients with preserved ejection fraction after transcatheter aortic valve implantation

Aims

Cardiac power output (CPO) measures cardiac performance, and its prognostic significance in heart failure with preserved ejection fraction (EF) has been previously reported. However, the effectiveness of CPO in risk stratification of patients with valvular heart disease and post-operative valvular disease has not been reported. We aimed to determine the association between CPO and clinical outcomes in patients with preserved left ventricular (LV) EF after transcatheter aortic valve implantation (TAVI).

Methods and results

This retrospective observational study included 1047 consecutive patients with severe aortic stenosis after TAVI. All patients were followed up for all-cause mortality and hospitalization for HF. CPO was calculated as 0.222 × cardiac output × mean blood pressure (BP)/LV mass, where 0.222 was the conversion constant to W/100 g of the LV myocardium. CPO was assessed using transthoracic echocardiography at discharge after TAVI. Of the 1047 patients, 253 were excluded following the exclusion criteria, including those with low LVEF, and 794 patients (84.0 [80.0-88.0] years; 35.8% male) were included in this study. During a median follow-up period of 684 (237-1114) days, the composite endpoint occurred in 196 patients. A dose-dependent association was observed between the CPO levels and all-cause mortality. Patients in the lowest CPO tertile had significantly lower event-free survival rates (log-rank test, P = 0.043). Multivariate Cox regression analysis showed that CPO was independently associated with adverse outcomes (hazard ratio = 0.561, P = 0.020). CPO provided an incremental prognostic effect in the model based on clinical and echocardiographic markers (P = 0.034).

Conclusion

CPO is independently and incrementally associated with adverse outcomes in patients with preserved LVEF following TAVI.

The effects of daily dose of intense exercise on cardiac responses and atrial fibrillation

Atrial fibrillation (AF) is a supraventricular tachyarrhythmia that is strongly associated with cardiovascular (CV) disease and sedentary lifestyles. Despite the benefits of exercise on overall health, AF incidence in high-level endurance athletes rivals that of CV disease patients, suggesting a J-shaped relationship with AF. To investigate the dependence of AF vulnerability on exercise, we varied daily swim durations (120, 180 or 240 min day-1 ) in 7-week-old male CD1 mice. We assessed mice after performing equivalent amounts of cumulative work during swimming (i.e. ∼700 L O2  kg-1 ), as determined from O2 consumption rates (V ̇ O 2 ${\dot V_{{{\mathrm{O}}_2}}}$ ). The meanV ̇ O 2 ${\dot V_{{{\mathrm{O}}_2}}}$ during exercise increased progressively throughout the training period and was indistinguishable between the swim groups. Consistent with similar improvements in aerobic conditioning induced by swimming, skeletal muscle mitochondria content increased (P = 0.027) indistinguishably between exercise groups. Physiological ventricular remodelling, characterized by mild hypertrophy and left ventricular dilatation, was also similar between exercised mice without evidence of ventricular arrhythmia inducibility. By contrast, prolongation of daily swim durations caused progressive and vagal-dependent heart rate reductions (P = 0.008), as well as increased (P = 0.005) AF vulnerability. As expected, vagal inhibition prolonged (P = 0.013) atrial refractoriness, leading to reduced AF vulnerability, although still inducible in the 180 and 240 min swim groups. Accordingly, daily swim dose progressively increased atrial hypertrophy (P = 0.003), fibrosis (P < 0.001) and macrophage accumulation (P = 0.006) without differentially affecting the ventricular tissue properties. Thus, increasing daily exercise duration drives progressively adverse atrial-specific remodelling and vagal-dependent AF vulnerability despite robust and beneficial aerobic conditioning and physiological remodelling of ventricles and skeletal muscle. KEY POINTS: Previous studies have suggested that a J-shaped dose-response relationship exists between physical activity and cardiovascular health outcomes, with moderate exercise providing protection against many cardiovascular disease conditions, whereas chronic endurance exercise can promote atrial fibrillation (AF). We found that AF vulnerability increased alongside elevated atrial hypertrophy, fibrosis and inflammation as daily swim exercise durations in mice were prolonged (i.e. ≥180 min day-1 for 6 weeks). The MET-h week-1 (based on O2  measurements during swimming) needed to induce increased AF vulnerability mirrored the levels linked to AF in athletes. These adverse atria effects associated with excessive daily exercise occurred despite improved aerobic conditioning, skeletal muscle adaptation and physiological ventricular remodelling. We suggest that atrial-specific changes observed with exercise arise from excessive elevations in venous filling pressures during prolonged exercise bouts, which we argue has implications for all AF patients because elevated atrial pressures occur in most cardiovascular disease conditions as well as ageing which are linked to AF.

Women have less progression of paroxysmal atrial fibrillation: data from the RACE V study

BACKGROUND

Sex differences in atrial fibrillation (AF) are observed in terms of comorbidities, symptoms, therapies received, AF progression and cardiovascular complications.

METHODS

We assessed the differences in prevalence and the determinants of AF progression, as well as the clinical characteristics and quality of life (QoL), between women and men with paroxysmal AF included in the RACE V (Reappraisal of Atrial Fibrillation: Interaction between hyperCoagulability, Electrical remodeling, and Vascular Destabilisation in the Progression of AF) study. At baseline, extensive phenotyping was done. To assess AF progression, implantable loop recorder (ILR) monitoring was used throughout follow-up. AF progression was defined as (1) progression to persistent or permanent AF or (2) progression of paroxysmal AF (>3% burden increase).

RESULTS

417 patients were included, 179 (43%) of whom were women. Women were older (median 67 years vs 63 years, p<0.001), less often had coronary artery disease (n=11 (6%) vs n=36 (16%), p=0.003), had more obesity (n=57 (32%) vs n=50 (21%), p=0.013), had less epicardial and pericardial fat (median 144 (interquartile range [IQR] 94-191) mL vs 199 (IQR 146-248) mL, p<0.001; and median 89 (ICQ 61-121) mL vs 105 (IQR 83-133) mL, p<0.001, respectively) and had more impaired left atrial function. The median follow-up was 2.2 (1.6-2.8) years. 51 of 417 patients (5.5% per year) showed AF progression (15/179 (8.4%) women and 36/238 (15.1%) men, p=0.032). Multivariable analysis showed tissue factor pathway inhibitor, N-terminal prohormone brain natriuretic peptide (NT-proBNP) and PR interval being associated with AF progression in women and factor XIIa:C1 esterase, NT-proBNP and proprotein convertase subtilisin/kexin type 9 in men. QoL was not different between sexes.

CONCLUSION

Despite older age, the incidence of AF progression was lower in women. Parameters associated with AF progression varied in part between sexes, suggesting different underlying pathophysiological mechanisms.

Cardiomyocyte and endothelial cells play distinct roles in the tumour necrosis factor (TNF)-dependent atrial responses and increased atrial fibrillation vulnerability induced by endurance exercise training in mice

AIMS

Endurance exercise is associated with an increased risk of atrial fibrillation (AF). We previously established that adverse atrial remodelling and AF susceptibility induced by intense exercise in mice require the mechanosensitive and pro-inflammatory cytokine tumour necrosis factor (TNF). The cellular and mechanistic basis for these TNF-mediated effects is unknown.

METHODS AND RESULTS

We studied the impact of Tnf excision, in either atrial cardiomyocytes or endothelial cells (using Cre-recombinase expression controlled by Nppa or Tie2 promoters, respectively), on the cardiac responses to six weeks of intense swim exercise training. TNF ablation, in either cell type, had no impact on the changes in heart rate, autonomic tone, or left ventricular structure and function induced by exercise training. Tnf excision in atrial cardiomyocytes did, however, prevent atrial hypertrophy, fibrosis, and macrophage infiltration as well as conduction slowing and increased AF susceptibility arising from exercise training. In contrast, endothelial-specific excision only reduced the training-induced atrial hypertrophy. Consistent with these cell-specific effects of Tnf excision, inducing TNF loss from atrial cardiomyocytes prevented activation of p38MAPKinase, a strain-dependent downstream mediator of TNF signalling, without affecting the atrial stretch as assessed by atrial pressures induced by exercise. Despite TNF's established role in innate immune responses and inflammation, neither acute nor chronic exercise training caused measurable NLRP3 inflammasome activation.

CONCLUSIONS

Our findings demonstrate that adverse atrial remodelling and AF vulnerability induced by intense exercise require TNF in atrial cardiomyocytes whereas the impact of endothelial-derived TNF is limited to hypertrophy modulation. The implications of the cell autonomous effects of TNF and crosstalk between cells in the atria are discussed.

The impact of image and performance enhancing drugs on atrial structure and function in resistance trained individuals

BACKGROUND

Image and performance enhancing drugs (IPEDs) are commonly used in resistance trained (RT) individuals and negatively impact left ventricular (LV) structure and function. Few studies have investigated the impact of IPEDs on atrial structure and function with no previous studies investigating bi-atrial strain. Additionally, the impact of current use vs. past use of IPEDs is unclear.

METHODS

Utilising a cross-sectional design, male (n = 81) and female (n = 15) RT individuals were grouped based on IPED user status: current (n = 57), past (n = 19) and non-users (n = 20). Participants completed IPED questionnaires, anthropometrical measurements, electrocardiography, and transthoracic echocardiography with strain imaging. Structural cardiac data was allometrically scaled to body surface area (BSA) according to laws of geometric similarity.

RESULTS

Body mass and BSA were greater in current users than past and non-users of IPEDs (p < 0.01). Absolute left atrial (LA) volume (60 ± 17 vs 46 ± 12, p = 0.001) and right atrial (RA) area (19 ± 4 vs 15 ± 3, p < 0.001) were greater in current users than non-users but this difference was lost following scaling (p > 0.05). Left atrial reservoir (p = 0.008, p < 0.001) and conduit (p < 0.001, p < 0.001) strain were lower in current users than past and non-users (conduit: current = 22 ± 6, past = 29 ± 9 and non-users = 31 ± 7 and reservoir: current = 33 ± 8, past = 39 ± 8, non-users = 42 ± 8). Right atrial reservoir (p = 0.015) and conduit (p = 0.007) strain were lower in current than non-users (conduit: current = 25 ± 8, non-users = 33 ± 10 and reservoir: current = 36 ± 10, non-users = 44 ± 13). Current users showed reduced LV diastolic function (A wave: p = 0.022, p = 0.049 and E/A ratio: p = 0.039, p < 0.001) and higher LA stiffness (p = 0.001, p < 0.001) than past and non-users (A wave: current = 0.54 ± 0.1, past = 0.46 ± 0.1, non-users = 0.47 ± 0.09 and E/A ratio: current = 1.5 ± 0.5, past = 1.8 ± 0.4, non-users = 1.9 ± 0.4, LA stiffness: current = 0.21 ± 0.7, past = 0.15 ± 0.04, non-users = 0.15 ± 0.07).

CONCLUSION

Resistance trained individuals using IPEDs have bi-atrial enlargement that normalises with allometric scaling, suggesting that increased size is, in part, associated with increased body size. The lower LA and RA reservoir and conduit strain and greater absolute bi-atrial structural parameters in current than non-users of IPEDs suggests pathological adaptation with IPED use, although the similarity in these parameters between past and non-users suggests reversibility of pathological changes with withdrawal.

The Brain-Heart Axis: Neuroinflammatory Interactions in Cardiovascular Disease

PURPOSE OF REVIEW

The role of neuroimmune modulation and inflammation in cardiovascular disease has been historically underappreciated. Physiological connections between the heart and brain, termed the heart-brain axis (HBA), are bidirectional, occur through a complex network of autonomic nerves/hormones and cytokines, and play important roles in common disorders.

RECENT FINDINGS

At the molecular level, advances in the past two decades reveal complex crosstalk mediated by the sympathetic and parasympathetic nervous systems, the renin-angiotensin aldosterone and hypothalamus-pituitary axes, microRNA, and cytokines. Afferent pathways amplify proinflammatory signals via the hypothalamus and brainstem to the periphery, promoting neurogenic inflammation. At the organ level, while stress-mediated cardiomyopathy is the prototypical disorder of the HBA, cardiac dysfunction can result from a myriad of neurologic insults including stroke and spinal injury. Atrial fibrillation is not necessarily a causative factor for cardioembolic stroke, but a manifestation of an abnormal atrial substrate, which can lead to the development of stroke independent of AF. Central and peripheral neurogenic proinflammatory factors have major roles in the HBA, manifesting as complex bi-directional relationships in common conditions such as stroke, arrhythmia, and cardiomyopathy.

Research on atrial fibrillation mechanisms and prediction of therapeutic prospects: focus on the autonomic nervous system upstream pathways

Atrial fibrillation (AF) is the most common clinical arrhythmia disorder. It can easily lead to complications such as thromboembolism, palpitations, dizziness, angina, heart failure, and stroke. The disability and mortality rates associated with AF are extremely high, significantly affecting the quality of life and work of patients. With the deepening of research into the brain-heart connection, the link between AF and stroke has become increasingly evident. AF is now categorized as either Known Atrial Fibrillation (KAF) or Atrial Fibrillation Detected After Stroke (AFDAS), with stroke as the baseline. This article, through a literature review, briefly summarizes the current pathogenesis of KAF and AFDAS, as well as the status of their clinical pharmacological and non-pharmacological treatments. It has been found that the existing treatments for KAF and AFDAS have limited efficacy and are often associated with significant adverse reactions and a risk of recurrence. Moreover, most drugs and treatment methods tend to focus on a single mechanism pathway. For example, drugs targeting ion channels primarily modulate ion channels and have relatively limited impact on other pathways. This limitation underscores the need to break away from the "one disease, one target, one drug/measurement" dogma for the development of innovative treatments, promoting both drug and non-drug therapies and significantly improving the quality of clinical treatment. With the increasing refinement of the overall mechanisms of KAF and AFDAS, a deeper exploration of physiological pathology, and comprehensive research on the brain-heart relationship, it is imperative to shift from long-term symptom management to more precise and optimized treatment methods that are effective for almost all patients. We anticipate that drugs or non-drug therapies targeting the central nervous system and upstream pathways can guide the simultaneous treatment of multiple downstream pathways in AF, thereby becoming a new breakthrough in AF treatment research.

Two-incision totally thoracoscopic mitral valve repair combined with radiofrequency atrial fibrillation ablation in rheumatic mitral valve disease: Early results of a case series of 43 consecutive patients

BACKGROUND

Few studies have reported the outcomes of two-incision total thoracoscopic mitral valve repair (MVr) and concomitant radiofrequency atrial fibrillation ablation (RAFA) in patients with rheumatic mitral valve disease and atrial fibrillation (AF).

METHODS

We retrospectively analyzed 43 consecutive patients who underwent MVr and RAFA through two-incision total thoracoscopic technique from October 2018 to June 2022. We collected data on baseline characteristics, perioperative outcomes, and early-term results.

RESULTS

The mean age was 55.67 ± 7.64 years and 29 (67.4%) patients had New York Heart Association (NYHA) class III or IV. The mean cardiopulmonary bypass (CPB) time was 115.56 ± 8.53 min and aortic clamping time was 81.42 ± 7.54 min. There were no in-hospital deaths or strokes. The mean preoperative mitral valve orifice area (MVOA) was 0.95 (0.84-1.16) cm2 and increased to 2.56 (2.41-2.87) cm2 at discharge and 2.54 (2.44-2.76) cm2 at 3 months after surgery (P < .001). At discharge, 32 (74.4%) patients were in sinus rhythm, 7 (20.9%) were in junctional or atrial flutter rhythm, and 4 (9.3%) remained in AF. At 6 months, 35 (81.4%) patients were in sinus rhythm, 5 (11.63%) were in junctional or atrial flutter rhythm, and 3 (4.7%) were in AF.

CONCLUSIONS

Two-incision total thoracoscopic MVr and RAFA is a safe and effective procedure that can improve the MVOA and promote conversion of AF to sinus rhythm in patients with rheumatic mitral valve disease and AF. Further studies with larger sample size and longer follow-up are needed to confirm the long-term benefits of this approach.

Engineered small extracellular vesicle-mediated NOX4 siRNA delivery for targeted therapy of cardiac hypertrophy

Small-interfering RNA (siRNA) therapy is considered a powerful therapeutic strategy for treating cardiac hypertrophy, an important risk factor for subsequent cardiac morbidity and mortality. However, the lack of safe and efficient in vivo delivery of siRNAs is a major challenge for broadening its clinical applications. Small extracellular vesicles (sEVs) are a promising delivery system for siRNAs but have limited cell/tissue-specific targeting ability. In this study, a new generation of heart-targeting sEVs (CEVs) has been developed by conjugating cardiac-targeting peptide (CTP) to human peripheral blood-derived sEVs (PB-EVs), using a simple, rapid and scalable method based on bio-orthogonal copper-free click chemistry. The experimental results show that CEVs have typical sEVs properties and excellent heart-targeting ability. Furthermore, to treat cardiac hypertrophy, CEVs are loaded with NADPH Oxidase 4 (NOX4) siRNA (siNOX4). Consequently, CEVs@siNOX4 treatment enhances the in vitro anti-hypertrophic effects by CEVs with siRNA protection and heart-targeting ability. In addition, the intravenous injection of CEVs@siNOX4 into angiotensin II (Ang II)-treated mice significantly improves cardiac function and reduces fibrosis and cardiomyocyte cross-sectional area, with limited side effects. In conclusion, the utilization of CEVs represents an efficient strategy for heart-targeted delivery of therapeutic siRNAs and holds great promise for the treatment of cardiac hypertrophy.

Causal effects between atrial fibrillation and heart failure: evidence from a bidirectional Mendelian randomization study

BACKGROUND

Observational studies have suggested a close association between atrial fibrillation (AF) and heart failure (HF), yet the causal effect remains uncertain. In this study, we employed a bidirectional Mendelian randomization analysis to investigate the causal effect of one disease on the other.

METHODS

Genetic instrumental variables were obtained from large-scale summary-level genome-wide association studies of AF (n = 1,030,836) and HF(n = 1,665,481), respectively. Two-sample Mendelian randomization was conducted to establish causal inferences. Inverse-variance weighted (IVW) was the primary estimate, while additional analyses including MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO), MR-Egger, and Weighted median were performed to validate robustness and identify pleiotropy.

RESULTS

After accounting for confounding variables, MR analysis suggested a potential causal relationship between AF and HF. An augmented genetic predisposition to atrial fibrillation was associated with an elevated risk of heart failure (odds ratio (OR) = 1.18, 95% confidence interval (CI):1.14-1.22). Likewise, genetically determined heart failure also increased the risk of heart failure (OR = 1.44, 95%CI:1.23-1.68). The robustness of the findings was corroborated through MR sensitivity analyses, and the causal estimates remained consistent when the instrument P-value threshold was tightened.

CONCLUSIONS

Our bidirectional Mendelian randomization study supports a reciprocal causal relationship between AF and HF. The shared genetic profile of these conditions may provide crucial insights into potential therapeutic targets for the prevention and progression of both disorders. These findings underscore the necessity for further investigation into the underlying molecular mechanisms linking AF and HF, as well as the potential for personalized treatment strategies grounded in genetic profiling.

Low atrial natriuretic peptide to brain natriuretic peptide ratio is associated with left atrial remodeling

AIMS

Atrial natriuretic peptide (ANP) deficiency is thought to be one of the causes of heart failure induced by atrial fibrillation (AF). Although ANP deficiency is thought to occur as a result of atrial remodeling, data to explain this mechanism are limited. The purpose of this study was to investigate the association between ANP and left atrial remodeling or prognosis of heart failure in patients with AF ablation.

METHODS

In total, 373 consecutive patients who underwent initial ablation for persistent AF [age, 67 ± 10 years; female, 97 (26%)] were retrospectively enrolled. ANP and brain natriuretic peptide (BNP) were measured before the procedure and the ANP/BNP ratio was calculated. Left atrial volume index, left atrial appendage emptying velocity, and left atrial low-voltage areas (LVAs) were used as left atrial-remodeling parameters. The primary outcome of heart failure was defined as the composite of all-cause death or hospitalization due to worsening heart failure.

RESULTS

The median ANP level was 116 (71-178) pg/ml and the median ANP/BNP ratio was 0.65 (0.46-1.00). The ANP/BNP ratio decreased with increasing left atrial volume index or LVAs and with decreasing left atrial appendage emptying velocity. During the 5-year follow-up, freedom from the primary outcome was significantly lower in patients with ANP/BNP ratio ≤0.65 than in those with ANP/BNP ratio >0.65 (84.6% versus 95.6%, P  < 0.01).

CONCLUSION

Secretion of ANP relative to BNP decreased with progression of left atrial remodeling in patients with AF ablation. Furthermore, prognosis of heart failure was poor in patients with a low ANP/BNP ratio.

An Exploration of the Relationship Between Atrial Fibrillation and Obesity

In the past 40 years, the prevalence of atrial fibrillation and obesity have skyrocketed. It has long been established that obesity can lead to adverse cardiovascular outcomes due to its myriad of effects on cardiovascular architecture, cardiovascular hemodynamics, and electrical conduction interference. The goal of this article is to explore the pathogenesis of atrial fibrillation in obese patients and examine the role of atrial enlargement, increased adipose deposits surrounding the pericardium, interstitial fibrosis, and inflammation in the development and worsening of atrial fibrillation in obese patients.

Personalized biomechanical insights in atrial fibrillation: opportunities & challenges

INTRODUCTION

Atrial fibrillation (AF) is an increasingly prevalent and significant worldwide health problem. Manifested as an irregular atrial electrophysiological activation, it is associated with many serious health complications. AF affects the biomechanical function of the heart as contraction follows the electrical activation, subsequently leading to reduced blood flow. The underlying mechanisms behind AF are not fully understood, but it is known that AF is highly correlated with the presence of atrial fibrosis, and with a manifold increase in risk of stroke.

AREAS COVERED

In this review, we focus on biomechanical aspects in atrial fibrillation, current and emerging use of clinical images, and personalized computational models. We also discuss how these can be used to provide patient-specific care.

EXPERT OPINION

Understanding the connection betweenatrial fibrillation and atrial remodeling might lead to valuable understanding of stroke and heart failure pathophysiology. Established and emerging imaging modalities can bring us closer to this understanding, especially with continued advancements in processing accuracy, reproducibility, and clinical relevance of the associated technologies. Computational models of cardiac electromechanics can be used to glean additional insights on the roles of AF and remodeling in heart function.

Mechanisms of Atrial Fibrillation in Obstructive Sleep Apnoea

Obstructive sleep apnoea (OSA) is a strong independent risk factor for atrial fibrillation (AF). Emerging clinical data cite adverse effects of OSA on AF induction, maintenance, disease severity, and responsiveness to treatment. Prevention using continuous positive airway pressure (CPAP) is effective in some groups but is limited by its poor compliance. Thus, an improved understanding of the underlying arrhythmogenic mechanisms will facilitate the development of novel therapies and/or better selection of those currently available to complement CPAP in alleviating the burden of AF in OSA. Arrhythmogenesis in OSA is a multifactorial process characterised by a combination of acute atrial stimulation on a background of chronic electrical, structural, and autonomic remodelling. Chronic intermittent hypoxia (CIH), a key feature of OSA, is associated with long-term adaptive changes in myocyte ion channel currents, sensitising the atria to episodic bursts of autonomic reflex activity. CIH is also a potent driver of inflammatory and hypoxic stress, leading to fibrosis, connexin downregulation, and conduction slowing. Atrial stretch is brought about by negative thoracic pressure (NTP) swings during apnoea, promoting further chronic structural remodelling, as well as acutely dysregulating calcium handling and electrical function. Here, we provide an up-to-date review of these topical mechanistic insights and their roles in arrhythmia.

Height Explains Sex Difference in Atrial Fibrillation Risk: Copenhagen General Population Study

OBJECTIVE

To test the hypothesis that the increased risk of atrial fibrillation (AF) in men compared with women is explained by height.

METHODS

From the Copenhagen General Population Study, we included 106,207 individuals (47,153 men and 59,054 women) from 20 to 100 years of age, without a prior diagnosis of AF, examined between November 25, 2003, and April 28, 2015. The main outcome was AF incidence from national hospital registers until April 2018. The association of risk factors with AF incidence was assessed by cause-specific Cox proportional hazards regression and Fine-Gray subdistribution hazards regression analysis.

RESULTS

During a maximum of 14.4 years of follow-up (median, 8.9 years), incident AF was observed in 3449 men and 2772 women with 845 (95% CI, 815 to 875) and 514 (95% CI, 494 to 535) events per 100,000 person-years, respectively. The age-adjusted hazard of incident AF was 63% (95% CI, 55% to 72%) higher in men compared with women. Risk factors for AF were generally similar in men and women, except men were taller than women (179 cm vs 166 cm, respectively; P<.001). When controlling for height, the difference in hazard of incident AF between sexes disappeared. For population attributable risk of AF, height was the most important risk factor investigated and explained 21% and 19% of the risk of incident AF in men and women, respectively.

CONCLUSION

A 63% higher risk of incident AF in men compared with women is explained by differences in height.

Establishment and Verification of a Nomogram for Predicting the Probability of New-Onset Atrial Fibrillation After Dual-Chamber Pacemaker Implantation

BACKGROUND

This study aims to establish and validate a nomogram as a predictive model in patients with new-onset atrial fibrillation (AF) after dual-chamber cardiac implantable electronic device (pacemaker) implantation.

METHODS

A total of 1120 Chinese patients with new-onset AF after pacemaker implantation were included in this retrospective study. Patients had AF of at least 180/minute lasting 5 minutes or longer, detected by atrial lead and recorded at least 3 months after implantation. Patients with previous atrial tachyarrhythmias before device implantation were excluded. A total of 276 patients were ultimately enrolled, with 51 patients in the AF group and 225 patients in the non-AF group. Least absolute shrinkage and selection operator (LASSO) method was used to determine the best predictors. Through multivariate logistic regression analysis, a nomogram was drawn as a predictive model. Concordance index, calibration plot, and decision curve analyses were applied to evaluate model discrimination, calibration, and clinical applicability. Internal verification was performed using a bootstrap method.

RESULTS

The LASSO method regression analysis found that variables including peripheral arterial disease, atrial pacing-ventricular pacing of at least 50%, atrial sense-ventricular sense of at least 50%, increased left atrium diameter, and age were important predictors of developing AF. In multivariate logistic regression, peripheral arterial disease, atrial pacing-ventricular pacing of at least 50%, and age were found to be independent predictors of new-onset AF.

CONCLUSION

This nomogram may help physicians identify patients at high risk of new-onset AF after pacemaker implantation at an early stage in a Chinese population.

Left atrial appendage thrombus formation, potential of resolution and association with prognosis in a large real-world cohort

Comprehensive data on factors influencing left atrial appendage (LAA) thrombus formation, resolution and impact on survival are limited. In this single-center, retrospective study 7759 (2010-2015) patients with symptomatic ongoing atrial fibrillation (AF) on admission were screened for LAA thrombi. 450 patients had LAA thrombi. 481 patients without LAA thrombi were randomly selected as controls. We assessed clinical, echocardiographic, laboratory parameters and long-term survival of both groups. Patients with LAA thrombi compared to controls were older, had more strokes, higher CHA₂DS₂ -VASc scores, worse renal function, less controlled diabetes, advanced heart failure, lower LAA emptying velocities, higher levels of cardiac and inflammatory markers (all p < 0.001). 56.3% of followed-up patients (304) dissolved their LAA thrombi. Chances of thrombus resolution increased with rising LAA flow velocities (OR 1.061, p = 0.022), whereas advanced age (OR 0.950, p < 0.001) and presence of permanent AF (OR 0.354, p < 0.001) decreased chances of thrombus resolution. Presence of LAA thrombi was associated with a markedly reduced 10-year survival probability (31% versus 69%). LAA thrombus formation is promoted by advanced structural heart disease, inflammation, diabetes and impaired renal function. Younger age, non-permanent AF and higher LAA flow velocities were predictors of thrombus resolution. Thrombus formation was associated with poor prognosis.

Impact of pulmonary arterial systolic pressure on patients with mitral valve disease combined with atrial fibrillation

Objective

To determine whether different changes of pulmonary artery systolic pressure (PASP) after surgeries have an impact on the long-term outcomes in patients with rheumatic and degenerative mitral valve (MV) disease and atrial fibrillation.

Methods

Between 2004 and 2016, 1,188 patients with rheumatic and degenerative MV disease undergoing MV and Cox-Maze procedure were identified. Clinic outcomes, as well as rhythm state and echocardiography indices in long-term follow-up were recorded. Patients were grouped by the changes of PASP (persistently normal, persistently increased, increased, and decreased) from preoperative estimation to follow-up.

Results

A complete echocardiography was performed at baseline and after 5 years. During follow-up, free of death and atrial fibrillation (AF) off antiarrhythmic drugs was 90 and 61%, 78 and 41% at 5 and 10 years, respectively. Survival rate was higher in patients with persistently normal and became worse in patients with persistently increased and increased PASP (log-rank 166.0, P < 0.0001). Moreover, the patients with persistently normal PASP had a lowest risk of recurrent AF (SHR: 0817; CI: 0.765-0.872; P < 0.0001) after considering death as a competing risk. A persistently normal PASP at follow-up and degenerative MV disease were associated with improved survival and sinus rhythm (SR) maintenance at multivariable Cox regression analysis (P < 0.05).

Conclusion

Patients with degenerative MV disease or have persistently normal PASP during follow-up have better survival and SR maintenance rate than patients with either rheumatic MV disease or persistently abnormal PASP.

Atrial Fibrillation, Thromboembolic Risk, and Anticoagulation in Cardiac Amyloidosis: A Review

Cardiac amyloidosis (CA) is caused by extracellular myocardial deposition of amyloid fibrils that are primary derived either from misfolding of transthyretin (ATTR) or light-chain (AL) proteins. CA is associated with atrial fibrillation, potentiated by electromechanical changes as a result of amyloid infiltration in the myocardium. CA also predisposes to thromboembolism and could potentially simultaneously elevate bleeding risk. In this review, we aim to explore and compare the prevalence and pathophysiological mechanisms of atrial fibrillation and thromboembolism in ATTR and AL, examine bleeding risk and factors that promote bleeding, and compare anticoagulation strategies in CA. Finally, we highlight knowledge gaps in the field of thromboembolism in CA to guide future research.

Genetic support of a causal relationship between iron status and atrial fibrillation: a Mendelian randomization study

Background

Atrial fibrillation is the most common arrhythmia disease. Animal and observational studies have found a link between iron status and atrial fibrillation. However, the causal relationship between iron status and AF remains unclear. The purpose of this investigation was to use Mendelian randomization (MR) analysis, which has been widely applied to estimate the causal effect, to reveal whether systemic iron status was causally related to atrial fibrillation.

Methods

Single nucleotide polymorphisms (SNPs) strongly associated (P < 5 × 10−8) with four biomarkers of systemic iron status were obtained from a genome-wide association study involving 48,972 subjects conducted by the Genetics of Iron Status consortium. Summary-level data for the genetic associations with atrial fibrillation were acquired from the AFGen (Atrial Fibrillation Genetics) consortium study (including 65,446 atrial fibrillation cases and 522,744 controls). We used a two-sample MR analysis to obtain a causal estimate and further verified credibility through sensitivity analysis.

Results

Genetically instrumented serum iron [OR 1.09; 95% confidence interval (CI) 1.02–1.16; p = 0.01], ferritin [OR 1.16; 95% CI 1.02–1.33; p = 0.02], and transferrin saturation [OR 1.05; 95% CI 1.01–1.11; p = 0.01] had positive effects on atrial fibrillation. Genetically instrumented transferrin levels [OR 0.90; 95% CI 0.86–0.97; p = 0.006] were inversely correlated with atrial fibrillation.

Conclusion

In conclusion, our results strongly elucidated a causal link between genetically determined higher iron status and increased risk of atrial fibrillation. This provided new ideas for the clinical prevention and treatment of atrial fibrillation.

Exploring the causality between ankylosing spondylitis and atrial fibrillation: A two-sample Mendelian randomization study

Objective: To study whether ankylosing spondylitis (AS) has a causal effect on the risk of atrial fibrillation (AF) using two-sample Mendelian randomization (MR) analysis. Methods: Single nucleotide polymorphisms (SNPs) were selected as independent instrumental variables (IVs) from a GWAS study of AS. Summary data from a large-scale GWAS meta-analysis of AF was utilized as the outcome dataset. Inverse-variance weighted (IVW) model was used for the primary analysis. Multiple sensitivity and heterogeneity tests were conducted to confirm the robustness of the results. Results: In total, 18 SNPs were identified as IVs for MR analysis. Five MR methods consistently found that ankylosing spondylitis was not causally associated with atrial fibrillation (IVW: OR = 0.983 (0.894, 1.080), p = 0.718; MR-Egger: OR = 1.190 (0.973, 1.456), p = 0.109; Simple mode: OR = 0.888 (0.718, 1.098), p = 0.287; Weighted mode: OR = 0.989 (0.854, 1.147), p = 0.890; Weight median: OR = 0.963 (0.852, 1.088), p = 0.545). Leave-one-out analysis supported the stability of MR results. Both the MR-Egger intercept and MR-PRESSO method revealed the absence of horizontal pleiotropy. Conclusion: The two-sample MR analysis did not support a causal relationship between AS and the risk of AF.

Cryoballoon ablation for atrial fibrillation in patients with heart failure with mildly reduced and preserved ejection fraction

AIMS

Limited data are available on the outcomes of cryoballoon ablation (CBA)-based pulmonary vein isolation (PVI) for atrial fibrillation (AF) in patients with heart failure (HF) with preserved ejection fraction (HFpEF) and mildly reduced ejection fraction (HFmrEF). The present study aimed to evaluate the safety and effectiveness of CBA in such patients.

METHODS AND RESULTS

Consecutive patients with AF referred for CBA-based PVI from two highly experienced electrophysiology centres were included in this retrospective study. Of 651 patients undergoing CBA, 471 cases were divided into four groups: No HF (n = 255), HFpEF (n = 101), HFmrEF (n = 78), and HF with reduced ejection fraction (n = 37). Similar early recurrence of atrial arrhythmia was found among groups (16.2% vs. 15.4% vs. 14.9% vs. 12.2%, P = 0.798), and no significant difference of long-term sinus rhythm (SR) maintenance was identified among the HFmrEF, HFpEF, and No HF groups (71.8% vs. 75.2% vs. 79.6%, P = 0.334). CBA is safe for patients with HFmrEF and HFpEF with similar complications compared with the No HF group (3.8% vs. 4.0% vs. 3.1%, P = 0.814). The reassessment of cardiac function after CBA showed that patients with HF indicated beneficial outcomes. Left atrial diameter (LAD) and left ventricular ejection fraction were significantly improved in the HFmrEF group. There were 41.6% of patients in the HFpEF group who were completely relieved from HF. LAD and New York Heart Association (NYHA) were associated with recurrence in the HFpEF and HFmrEF groups, and the maintenance of SR was an independent predictor of NYHA improvement for all HF groups.

CONCLUSIONS

Patients with HFmrEF and HFpEF could benefit from CBA with high SR maintenance and significant HF improvement.

Regional and temporal progression of atrial remodeling in angiotensin II mediated atrial fibrillation

Atrial fibrillation (AF) is associated with electrical and structural remodeling in the atria; however, the regional and temporal progression of atrial remodeling is incompletely understood. The objective of this study was to investigate the regional and temporal progression of atrial remodeling leading to changes in AF susceptibility in angiotensin II (Ang II) mediated hypertension. Mice were infused with Ang II for 3, 10 or 21 days. AF susceptibility and atrial electrophysiology were studied in vivo using intracardiac electrophysiology. Right and left atrial myocyte electrophysiology was studied using patch-clamping. Atrial fibrosis was assessed histologically. P wave duration and atrial effective refractory period increased progressively from 3 to 21 days of Ang II. AF susceptibility tended to be increased at 10 days of Ang II and was elevated at 21 days of Ang II. Left, but not right, atrial AP upstroke velocity and Na+ current were reduced at 10 and 21 days of Ang II. Left atrial action potential (AP) duration increased progressively from 3 to 21 days of Ang II due to reductions in repolarizing K+ current. Right atrial AP prolongation was increased only after 21 days of Ang II. Left and right atrial fibrosis developed progressively from 3 to 21 days, but increases were larger in the left atrium. In conclusion, Ang II mediated atrial electrical and structural remodeling develop earlier and more extensively in the left atrium compared to the right atrium, providing insight into how atrial remodeling leads to enhanced AF susceptibility in Ang II mediated hypertension.

New onset atrial fibrillation during orthotopic liver transplantation induced by iced saline injection for transpulmonary thermodilution: a case report

Transpulmonary thermodilution is often used to measure extravascular lung water during liver transplantation. Here, the case of new onset atrial fibrillation during orthotopic liver transplantation, which may have been induced by iced saline injection for transpulmonary thermodilution measurement, is described. A 52-year-old male patient underwent orthotopic liver transplantation due to alcoholic cirrhosis combined with portal hypertension. During dissection of the recipient liver, transpulmonary thermodilution was performed. At 3 minutes following iced saline injected, atrial fibrillation occurred, the ventricular rate increased to more than 120 beats per min, and blood pressure dropped to 75/50 mmHg. Massive haemorrhage, inferior vena cava clamping, electrolyte disorder, acid-base balance disorder, and hypothermia were all ruled out, and iced saline injection was suspended. Hemodynamic stability was maintained with phenylephrine and lanatocide C (cedilanid), and chemical cardioversion was performed using amiodarone. During the reperfusion phase, transient hemodynamic instability was managed by norepinephrine. The neohepatic phase was uneventful. Atrial fibrillation lasted for 5 days and reversed to sinus rhythm automatically. The patient was hemodynamically stable during this period, and recovery was smooth with no thromboembolic events. In conclusion, atrial fibrillation may be induced by iced saline injection for transpulmonary thermodilution measurement during orthotopic liver transplantation.

Asymptomatic left circumflex artery stenosis is associated with higher arrhythmia recurrence after persistent atrial fibrillation ablation

Background

The pathophysiology of persistent atrial fibrillation (AF) remains unclear. While several studies have demonstrated an association between myocardial infarction and atrial fibrillation, the role of stable coronary artery disease (CAD) is still unknown. As a result, we aimed to assess the association between CAD obstruction and AF recurrence after persistent AF ablation in patients with no history of CAD.

Materials and methods

This observational retrospective study included consecutive patients who underwent routine preprocedural cardiac computed tomography (CCT) before persistent AF ablation between September 2015 and June 2018 in 5 European University Hospitals. Exclusion criteria were CAD or coronary revascularization previously known or during follow-up. Obstructive CAD was defined as luminal stenosis ≥ 50%.

Results

All in all, 496 patients (mean age 61.8 ± 10.0 years, 76.2% males) were included. CHA₂DS₂–VASc score was 0 or 1 in 225 (36.3%) patients. Obstructive CAD was present in 86 (17.4%) patients. During the follow-up (24 ± 19 months), 207 (41.7%) patients had AF recurrence. The recurrence rate was not different between patients with and without obstructive CAD (43.0% vs. 41.5%, respectively; P = 0.79). When considering the location of the stenosis, the recurrence rate was higher in the case of left circumflex obstruction: 56% vs. 32% at 2 years (log-rank P ≤ 0.01). After Cox multivariate analysis, circumflex artery obstruction (HR 2.32; 95% CI 1.36–3.98; P < 0.01) was independently associated with AF recurrence.

Conclusion

Circumflex artery obstruction detected with CCT was independently associated with 2-fold increase in the risk of AF recurrence after persistent AF ablation. Further research is necessary to evaluate this pathophysiological relationship.

Identification of Distinct Subgroups in Moderately Severe Rheumatic Mitral Stenosis Using Data-Driven Phenotyping of Longitudinal Hemodynamic Progression

Background

Rheumatic mitral stenosis is a significant cause of valvular heart disease. Pulmonary arterial systolic pressure (PASP) reflects the hemodynamic consequences of mitral stenosis and is used to determine treatment strategies. However, PASP progression and expected outcomes based on PASP changes in patients with moderately severe mitral stenosis remain unclear.

Methods and Results

A total of 436 patients with moderately severe rheumatic mitral stenosis (valve area 1.0–1.5 cm²) were enrolled. Composite outcomes included all‐cause mortality and hospitalization for heart failure. Data‐driven phenotyping identified 2 distinct trajectory groups based on PASP progression: rapid (8.7%) and slow (91.3%). Patients in the rapid progression group were older and had more diabetes and atrial fibrillation than those in the slow progression group (all P<0.05). The initial mean diastolic pressure gradient and PASP were higher in the rapid progression group than in the slow progression group (6.2±2.4 mm Hg versus 5.1±2.0 mm Hg [P=0.001] and 42.3±13.3 mm Hg versus 33.0±9.2 mm Hg [P<0.001], respectively). The rapid progression group had a poorer event‐free survival rate than the slow progression group (log‐rank P<0.001). Rapid PASP progression was a significant risk factor for composite outcomes even after adjusting for comorbidities (hazard ratio, 3.08 [95% CI, 1.68–5.64]; P<0.001). Multivariate regression analysis revealed that PASP >40 mm Hg was independently associated with allocation to the rapid progression group (odds ratio, 4.95 [95% CI, 2.08–11.99]; P<0.001).

Conclusions

Rapid PASP progression was associated with a higher risk of the composite outcomes. The main independent predictor for rapid progression group allocation was initial PASP >40 mm Hg.

Prevalence and determinants of atrial fibrillation progression in paroxysmal atrial fibrillation

OBJECTIVE

Atrial fibrillation (AF) often progresses from paroxysmal AF (PAF) to more permanent forms. To improve personalised medicine, we aim to develop a new AF progression risk prediction model in patients with PAF.

METHODS

In this interim-analysis of the Reappraisal of AF: Interaction Between HyperCoagulability, Electrical Remodelling, and Vascular Destabilisation in the Progression of AF study, patients with PAF undergoing extensive phenotyping at baseline and continuous rhythm monitoring during follow-up of ≥1 year were analysed. AF progression was defined as (1) progression to persistent or permanent AF or (2) progression of PAF with >3% burden increase. Multivariable analysis was done to identify predictors of AF progression.

RESULTS

Mean age was 65 (58-71) years, 179 (43%) were female. Follow-up was 2.2 (1.6-2.8) years, 51 of 417 patients (5.5%/year) showed AF progression. Multivariable analysis identified, PR interval, impaired left atrial function, mitral valve regurgitation and waist circumference to be associated with AF progression. Adding blood biomarkers improved the model (C-statistic from 0.709 to 0.830) and showed male sex, lower levels of factor XIIa:C1-esterase inhibitor and tissue factor pathway inhibitor, and higher levels of N-terminal pro-brain natriuretic peptide, proprotein convertase subtilisin/kexin type 9 and peptidoglycan recognition protein 1 were associated with AF progression.

CONCLUSION

In patients with PAF, AF progression occurred in 5.5%/year. Predictors for progression included markers for atrial remodelling, sex, mitral valve regurgitation, waist circumference and biomarkers associated with coagulation, inflammation, cardiomyocyte stretch and atherosclerosis. These prediction models may help to determine risk of AF progression and treatment targets, but validation is needed.

TRIAL REGISTRATION NUMBER

NCT02726698.

MR-proANP measured at admission is associated with incident atrial fibrillation in STEMI patients

Atrial fibrillation (AF) is common following ST-segment elevation myocardial infarction (STEMI). Increased blood levels of mid regional pro atrial natriuretic peptide (MR-proANP) have been associated with a greater risk of incident AF. However, knowledge of the value of MR-proANP in predicting incident AF after STEMI is sparse. To assess whether MR-proANP measured at admission is associated with development of incident AF in patients with STEMI. 673 STEMI patients with no history of AF treated with primary percutaneous coronary intervention (pPCI) were prospectively enrolled from September 2006 to December 2008. Blood samples were drawn before the procedure. MR-proANP was measured by an automated processing assay. End point was incident AF. Median follow-up time was 5.5 years (interquartile-range 4.7-6.0), during which 63 patients developed AF. In a multivariable Cox regression model adjusted for relevant clinical and biochemical variables, MR-proANP was significantly associated with the development of AF (HR 1.18 per 100 pmol, 95% CI 1.11-1.28, p < 0.001). In a subgroup of patients who underwent echocardiography (N = 360), MR-proANP remained significantly associated with the development of AF (HR 1.39 per 100 pmol, 95% CI 1.13-1.71, p = 0.002) after adjusting for clinical and biochemical variables and left ventricular ejection fraction. When stratifying patients according to tertiles of MR-proANP, patients in the upper tertile displayed an 11 times greater risk of developing AF during follow-up as compared to patients in the lower tertile (HR 11.1, 95% CI 4.4-28.2, p < 0.001). Plasma MR-proANP measured at admission is an independent predictor of incident AF after STEMI.

Catheter ablation of atrial fibrillation in patients with heart failure and preserved ejection fraction: A meta-analysis

Background

Catheter ablation (CA) is an effective treatment for patients with atrial fibrillation (AF). The potential of CA to benefit AF patients with heart failure and preserved ejection fraction (HFpEF) is uncertain.

Hypothesis

CA may be safe and effective for patients with HFpEF.

Methods

The Medline, PubMed, Embase, and Cochrane Library databases were searched for studies evaluating CA for AF patients with HFpEF.

Results

A total of seven trials with 1696 patients were included. Pooled analyses demonstrated similar procedure and fluoroscopy time regarding the use of CA for patients with HFpEF and without HF (weighted mean difference [WMD]: 0.40; 95% confidence interval (CI): −0.01–0.81, p = .05 and [WMD: 0.05; 95% CI: −0.18–0.28, p = .68]). Moreover, CA was effective in maintaining sinus rhythm (SR) in patients with HFpEF and noninferior for patients without HF [risk ratio (RR): 0.92; 95% CI: 0.76–1.10, p = .34). Additionally, CA tended to significantly maintain SR (RR: 4.73; 95% CI: 1.86–12.03, p = .001) and reduce rehospitalization for HF compared with medical therapy (RR: 0.36; 95% CI: 0.19–0.71, p = .003). However, no significant differences were found between two groups regarding the mortality rate (p = .59).

Conclusion

CA is a potential treatment strategy for patients with HFpEF and demonstrates equivalent efficacy to that of patients without HF. Moreover, the benefits of CA in maintaining SR and reducing rehospitalization of HF patients were significantly better than those of medical therapy. Additional randomized controlled trials are warranted to confirm our results.

Anabolic Steroids Use Is Associated with Impairments in Atrial and Ventricular Cardiac Structure and Performance in Athletes

PURPOSE

Despite potential severe cardiac side effects, anabolic androgenic steroids (AAS) are increasingly used by strength athletes. However, previous echocardiographic studies focused on the left ventricular (LV) strains but did not assess LV twist and untwist mechanics. Moreover, left atrial (LA) function has been often neglected, and its stiffness, an important determinant of LA reservoir function, has never been challenged. The aim of this study was to investigate the effects of AAS on LA and LV morphologies and functions in strength athletes.

METHODS

Fifty subjects including 20 strength-trained young athletes age 32.0 ± 8.5 yr with a mean duration of AAS use of 4.7 ± 1.8 yr (users), 15 athletes with no history of AAS use (nonusers) and 15 sedentary controls underwent speckle tracking echocardiography to assess LA and LV morphology and function.

RESULTS

Users showed higher LA reservoir dysfunction than nonusers (33.7% ± 10.9% vs 44.9% ± 9.9% respectively, P = 0.004) and higher LA stiffness (0.13 ± 0.05 vs 0.19 ± 0.08 A.U., respectively; P = 0.02), higher LV mass index and lower global and regional LV diastolic and systolic dysfunction (global longitudinal strain: -15.5% ± 3.2% vs -18.9% ± 1.8% respectively; P = 0.003), with a drop of LV twist-untwist mechanics (untwisting velocity: 61.5°·s-1 ± 20.2°·s-1 vs 73.7°·s-1 ± 16.1°·s-1 respectively, P = 0.04). There were significant correlations between LV mass and LV apical rotation (P = 0.003, r = 0.44) and diastolic longitudinal strain rate (P = 0.015, r = 0.33).

CONCLUSIONS

Our results showing significant LA and LV remodeling and dysfunctions in young AAS using athletes are alarming. Screening echocardiography based on speckle tracking echocardiography parameters for early diagnosis, as well as a stronger awareness in athletes and in physicians are warranted in this context.

Effects of weight loss after bariatric surgery on atrial electromechanical delay in obese subjects

Background: The authors investigated the relationship between weight loss after sleeve gastrectomy and change in atrial electromechanical delay values. Methods: A total of 41 patients were included. The primary end point was any effect of total weight loss on atrial electromechanical delay parameters. Results: The mean loss of body weight was 25.50 ± 11.07 kg. There was a significant correlation between mean body weight change and change in interatrial and left intra-atrial electromechanical delays (Pearson's correlation coefficient: 0.575 and 0.871, respectively; p < 0.001). Only change in body weight was significantly related to change in interatrial electromechanical delay (regression coefficient: 0.707; p < 0.01). Conclusion: In this study, a significant relationship was found between amount of body weight loss and decrease in atrial electromechanical values.

The Critical Roles of Proteostasis and Endoplasmic Reticulum Stress in Atrial Fibrillation

Atrial fibrillation (AF) remains the most common arrhythmia seen clinically. The incidence of AF is increasing due to the aging population. AF is associated with a significant increase in morbidity and mortality, yet current treatment paradigms have proven largely inadequate. Therefore, there is an urgent need to develop new effective therapeutic strategies for AF. The endoplasmic reticulum (ER) in the heart plays critical roles in the regulation of excitation-contraction coupling and cardiac function. Perturbation in the ER homeostasis due to intrinsic and extrinsic factors, such as inflammation, oxidative stress, and ischemia, leads to ER stress that has been linked to multiple conditions including diabetes mellitus, neurodegeneration, cancer, heart disease, and cardiac arrhythmias. Recent studies have documented the critical roles of ER stress in the pathophysiological basis of AF. Using an animal model of chronic pressure overload, we demonstrate a significant increase in ER stress in atrial tissues. Moreover, we demonstrate that treatment with a small molecule inhibitor to inhibit the soluble epoxide hydrolase enzyme in the arachidonic acid metabolism significantly reduces ER stress as well as atrial electrical and structural remodeling. The current review article will attempt to provide a perspective on our recent understandings and current knowledge gaps on the critical roles of proteostasis and ER stress in AF progression.

Increased expression of six-large extracellular vesicle-derived miRNAs signature for nonvalvular atrial fibrillation

Backgrounds

Non-valvular atrial fibrillation (AF) is the most common type of cardiac arrhythmia. AF is caused by electrophysiological abnormalities and alteration of atrial tissues, which leads to the generation of abnormal electrical impulses. Extracellular vesicles (EVs) are membrane-bound vesicles released by all cell types. Large EVs (lEVs) are secreted by the outward budding of the plasma membrane during cell activation or cell stress. lEVs are thought to act as vehicles for miRNAs to modulate cardiovascular function, and to be involved in the pathophysiology of cardiovascular diseases (CVDs), including AF. This study identified lEV-miRNAs that were differentially expressed between AF patients and non-AF controls.

Methods

lEVs were isolated by differential centrifugation and characterized by Nanoparticle Tracking Analysis (NTA), Transmission Electron Microscopy (TEM), flow cytometry and Western blot analysis. For the discovery phase, 12 AF patients and 12 non-AF controls were enrolled to determine lEV-miRNA profile using quantitative reverse transcription polymerase chain reaction array. The candidate miRNAs were confirmed their expression in a validation cohort using droplet digital PCR (30 AF, 30 controls). Bioinformatics analysis was used to predict their target genes and functional pathways.

Results

TEM, NTA and flow cytometry demonstrated that lEVs presented as cup shape vesicles with a size ranging from 100 to 1000 nm. AF patients had significantly higher levels of lEVs at the size of 101–200 nm than non-AF controls. Western blot analysis was used to confirm EV markers and showed the high level of cardiomyocyte expression (Caveolin-3) in lEVs from AF patients. Nineteen miRNAs were significantly higher (> twofold, p < 0.05) in AF patients compared to non-AF controls. Six highly expressed miRNAs (miR-106b-3p, miR-590-5p, miR-339-3p, miR-378-3p, miR-328-3p, and miR-532-3p) were selected to confirm their expression. Logistic regression analysis showed that increases in the levels of these 6 highly expressed miRNAs associated with AF. The possible functional roles of these lEV-miRNAs may involve in arrhythmogenesis, cell apoptosis, cell proliferation, oxygen hemostasis, and structural remodeling in AF.

Conclusion

Increased expression of six lEV-miRNAs reflects the pathophysiology of AF that may provide fundamental knowledge to develop the novel biomarkers for diagnosis or monitoring the patients with the high risk of AF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03213-6.

The Association Between Recurrence of Atrial Fibrillation and Revascularization in Patients With Coronary Artery Disease After Catheter Ablation

Aim: The connection between revascularization for coronary artery disease (CAD) and the incidence of recurrent events of atrial fibrillation (AF) after ablation is unclear. This study aimed to explore the relationship between coronary revascularization and AF recurrence in patients who underwent radiofrequency catheter ablation (RFCA). Methods: Four hundred and nineteen patients who underwent performed coronary angiography at the same time as RFCA were enrolled in this study. Obstructive CAD was defined as at least one coronary artery vessel stenosis of ≥75% and percutaneous coronary intervention (PCI) was recommended. Non-obstructive CAD was defined as coronary artery vessel stenosis of <75%. The endpoint was freedom from recurrence from AF after RFCA during the 24-month follow-up. Results: In total, 102, 95, and 212 patients were undergone coronary angiography and diagnosed as having obstructive CAD, Non-obstructive CAD, and Non-CAD, respectively. During the 24-month follow-up period, patients without obstructive CAD were significantly more likely to achieve freedom from AF than patients with obstructive CAD (hazard ratio [HR]: 1.72; 95% confidence interval [CI]: 1.23-2.41; P = 0.001). The recurrence rate of AF was significantly lower in patients who underwent PCI than in those who did not (HR: 0.45; 95% CI: 0.25-0.80; P = 0.007). The multivariate regression analysis showed that the other predictors of AF recurrence for obstructive CAD were multivessel stenosis (HR: 1.92; 95% CI: 1.04-3.54; P = 0.036) and left atrial diameter (HR: 2.56; 95% CI: 1.31-5.00; P = 0.006). Conclusions: This study suggests that obstructive CAD is associated with a higher rate of AF recurrence. Additionally, For patients with CAD, coronary revascularization is related to a lower recurrence rate of AF after RFCA.

Analyzing artificial intelligence systems for the prediction of atrial fibrillation from sinus-rhythm ECGs including demographics and feature visualization

Atrial fibrillation (AF) is an abnormal heart rhythm, asymptomatic in many cases, that causes several health problems and mortality in population. This retrospective study evaluates the ability of different AI-based models to predict future episodes of AF from electrocardiograms (ECGs) recorded during normal sinus rhythm. Patients are divided into two classes according to AF occurrence or sinus rhythm permanence along their several ECGs registry. In the constrained scenario of balancing the age distributions between classes, our best AI model predicts future episodes of AF with area under the curve (AUC) 0.79 (0.72-0.86). Multiple scenarios and age-sex-specific groups of patients are considered, achieving best performance of prediction for males older than 70 years. These results point out the importance of considering different demographic groups in the analysis of AF prediction, showing considerable performance gaps among them. In addition to the demographic analysis, we apply feature visualization techniques to identify the most important portions of the ECG signals in the task of AF prediction, improving this way the interpretability and understanding of the AI models. These results and the simplicity of recording ECGs during check-ups add feasibility to clinical applications of AI-based models.

Relationship among atrial fibrillation, the CHA2DS2-VASc score and ischaemic stroke in patients with coronary artery disease: a propensity score matching study in Hebei, China

Background

Recent evidence has shown that the pathogenesis of ischaemic stroke associated with atrial fibrillation (AF) is complex and involves other factors in addition to arrhythmias. The purpose of this study was to investigate the relationship among AF, CHA₂DS₂-VASc score and ischaemic stroke in patients with coronary artery disease (CAD) in Hebei, China.

Methods

A total of 2,335 patients with CAD from September 2016 to May 2019 at the Second Hospital of Hebei Medical University were included (mean age 62.73 ± 10.35 years, range 26–92 years; 41.58% female). This was a cross-sectional study, and participants were divided into non-stroke (n = 1997) and ischaemic stroke groups (n = 338). Propensity score matching (PSM) was performed to match ischaemic stroke patients with non-stroke patients in a 1:4 ratio. The relationship among AF, the CHA₂DS₂-VASc score and ischaemic stroke was evaluated using univariable generalized linear models for different sex, age, body mass index (BMI), CAD and CHA₂DS₂-VASc score subgroups. Univariable and multivariable generalized linear models were used to evaluate the relationship between AF and ischaemic stroke in the different models.

Results

Compared with that in the non-stroke group, the prevalence of AF (8.81% vs. 14.20%, P = 0.002) in the ischaemic stroke group was higher. The proportion of patients with ischaemic stroke was significantly different between the AF group and the non-AF group (28.74% vs. 19.04%, P = 0.003). An increasing CHA₂DS₂-VASc score was associated with a gradual increase in the prevalence of AF (P for trend < 0.001). Subgroup analysis showed that the trend towards increased stroke risk in the AF group was consistent across the various subgroups. The multivariable analysis demonstrated that AF was not associated with ischaemic stroke compared with the absence of AF (OR = 1.55, 95% CI 0.94–2.56, P = 0.087).

Conclusion

In our cross-sectional study, after adjustment for confounding factors, there was no association between AF and ischaemic stroke. The increased risk of ischaemic stroke associated with AF was attenuated by atherosclerotic factors. Our study supports the current view that enhanced control of modifiable cardiovascular risk factors in patients with AF is essential.

A New Vision at the Interface of Atrial Fibrillation and Stroke

Introduction: Current evidence questions the linear sequence traditionally described in atrial fibrillation, blood stasis, intracavitary thrombus, and embolization to the central nervous system. Currently, new perspectives have been described based on questions from the linearly traditional chronology of events; it is within this scope that the article has its objective.

Evidences: The association of the two entities is biologically plausible and supported by different cohorts with a higher risk of developing atrial fibrillation, especially in the cardioembolic form. Concepts (temporal dissociation, biological gradient, etc.) determine the existence of other factors associated with cardioembolism, not exclusively by atrial fibrillation. The entire cascade of events associated with myopathy and atrial remodeling can generate damage to the myocyte and amplify the prothrombotic status. It is important to clarify that atrial myopathy can present itself as atrial fibrillation initially or not, but should always be considered thrombogenic in all the contexts of their clinical presentation. Considering atrial heart disease as a cause of embolic stroke, it could explain that one-third of strokes are considered cryptogenic.

Conclusions: The traditional model exclusively associating the presence of atrial fibrillation in the genesis of thromboembolism is incomplete. The concept of atrial cardiopathy where cardioembolism occurs in a non-atrial fibrillation dependent manner fits better with current data. The future challenge is to effectively detect the various manifestations of atrial heart disease, generating direct implications for the identification of patients at risk of stroke and also for better management after a cardioembolic event.

Atrial Fibrillation Recurrence Prevention after Electrical Cardioversion in High-Risk Patients – Benefits of Non-Antiarrhythmic Drugs

Background:

Recurrence prevention after Atrial Fibrillation (AF) termination by Eelectrical Cardioversion (ECV) remains challenging. Increasing attention is paid to pathophysiological effects of non-Antiarrhythmic Drugs (non-AADs), nevertheless, with heterogeneous results.

Objective:

We evaluated the potential benefits of different non-AADs as adjunctive therapy to Antiarrhythmic Drugs (AADs) for AF recurrence prevention after sinus rhythm restoration by ECV in high-risk patients.

Methods:

The study was conducted among high-risk AF patients after successful ECV. Prescription of class IC or class III AAD was required. Data were acquired in a face-to-face baseline interview and 1-, 3-, 6-, 9-, 12-month follow-up interviews.

Results:

113 patients were included. Total AF recurrence rate reached 48.7%. Angiotensin-Converting Enzyme Inhibitor (ACEI) or angiotensin receptor blocker (ARB) intake, compared with non-use, demonstrated AF recurrence rate reduction by 8.5% (46.3 vs. 54.8%), with odds ratio (OR) reduced by 28.9% (OR 0.711, 95% confidence interval (CI) 0.310-1.631, p = 0.420). Among mineralocorticoid receptor antagonist (MRA) users, AF recurrence rate was reduced by 25.1% (29.6 vs. 54.7%) and OR by 65.1% (OR 0.349, 95%CI 0.138-0.884, p = 0.023). Present statin therapy reduced AF recurrence rate by 4.2% (46.8 vs. 51.0%) and OR by 15.5% (OR 0.845, 95%CI 0.402-1.774, p = 0.656). Diuretic use showed reduction of AF recurrence rate by 10.2% (41.7 vs. 51.9%) and OR by 33.9% (OR 0.661, 95%CI 0.297-1.469, p = 0.308).

Conclusion:

Non-AADs demonstrated practical benefits as adjunctive therapy to AADs for AF recurrence prevention after ECV in high-risk patients, with statistically significant results established for concomitant MRA intake.

Exercising immune cells: The immunomodulatory role of exercise on atrial fibrillation

Exercise training is generally beneficial for cardiovascular health, improving stroke volume, cardiac output, and aerobic capacity. Despite these benefits, some evidence indicates that endurance training may increase the risk of atrial fibrillation (AF), particularly in highly trained individuals. Among multiple mechanisms, autonomic tone changes and atrial remodeling have been proposed as main contributors for exercise-induced AF. However, the contribution of local and systemic immunity is poorly understood in the development of atrial arrhythmogenic substrates. Here we aim to update the field of immunomodulation in the context of exercise and AF by compiling and reconciling the most recent evidence from preclinical and human studies and rationalize the applicability of "lone" AF terminology in athletes.

Secondary Stroke Prevention Following Embolic Stroke of Unknown Source in the Absence of Documented Atrial Fibrillation: A Clinical Review

Approximately one-third of ischemic strokes are classified as cryptogenic strokes. The risk of stroke recurrence in these patients is significantly elevated with up to one-third of patients with cryptogenic stroke experiencing a further stroke within 10 years. While anticoagulation is the mainstay of treatment for secondary stroke prevention in the context of documented atrial fibrillation (AF), it is estimated that up to 25% of patients with cryptogenic stroke have undiagnosed AF. Furthermore, the historical acceptance of a causal relationship between AF and stroke has recently come under scrutiny, with evidence to suggest that embolic stroke risk may be elevated even in the absence of documented atrial fibrillation attributable to the presence of electrical and structural changes constituting an atrial cardiomyopathy. More recently, the term embolic stroke of unknown source has garnered increasing interest as a subset of patients with cryptogenic stroke in whom a minimum set of diagnostic investigations has been performed, and a nonlacunar infarct highly suspicious of embolic etiology is suspected but in the absence of an identifiable secondary cause of stroke. The ongoing ARCADIA (Atrial Cardiopathy and Antithrombotic Drugs in Prevention After Cryptogenic Stroke) randomized trial and ATTICUS (Apixiban for Treatment of Embolic Stroke of Undetermined Source) study seek to further define this novel term. This review summarizes the relationship between AF, embolic stroke, and atrial cardiomyopathy and provides an overview of the clinical relevance of cardiac imaging, electrocardiographic, and serum biomarkers in the assessment of AF and secondary stroke risk. The implications of these findings on therapeutic considerations is considered and gaps in the literature identified as areas for future study in risk stratifying this cohort of patients.