Role of the autonomic nervous system in atrial fibrillation: pathophysiology and therapy

Association between blood pressure levels and premature atrial contractions in patients with hypertension

BACKGROUND

High blood pressure (BP) induces left atrial structural and functional remodeling that increases susceptibility to atrial arrhythmia. We hypothesized that lower systolic BP (SBP) levels are associated with a lower prevalence of premature atrial contractions (PACs) in patients with hypertension.

METHODS

This analysis included 4,697 participants (mean age 62±13.1 years, 50% women, 25.6% blacks) with hypertension from the Third National Health and Nutrition Examination Survey who did not have a prior history of cardiovascular disease (CVD). Multivariable logistic regression was used to examine the cross-sectional association between SBP and prevalence of PACs ascertained from 12-lead resting electrocardiograms. Multivariable Cox proportional hazard analysis was used to examine the association between baseline PACs and CVD mortality.

RESULTS

Approximately 1.6% (n=74) of participants had baseline PACs. Patients with SBP ≤140 mmHg had a lower prevalence of PACs than those with SBP ≥140 mmHg (1.1% vs. 1.9%, p-value=0.01). In a multivariable logistic regression model, each 10 mmHg decrease in SBP was associated with a 12% lower odds of PACs (OR (95%CI): 0.88 (0.77-0.99)). During 14 years of follow-up, 645 CVD deaths occurred. In a multivariable-adjusted Cox model, presence of PACs was associated with a 78% increased risk of CVD mortality (HR (95%CI): 1.78 (1.23-2.60)).

CONCLUSIONS

In patients with hypertension, lower SBP levels are associated with a lower prevalence of PACs, and presence of PACs is associated with a higher risk of CVD mortality risk. These findings highlight the potential role of BP lowering in the management of cardiac arrhythmias.

Aging-associated atrial fibrillation: A comprehensive review focusing on the potential mechanisms

Atrial fibrillation (AF) has been receiving a lot of attention from scientists and clinicians because it is an extremely common clinical condition. Due to its special hemodynamic changes, AF has a high rate of disability and mortality. So far, although AF has some therapeutic means, it is still an incurable disease because of its complex risk factors and pathophysiologic mechanisms, which is a difficult problem for global public health. Age is an important independent risk factor for AF, and the incidence of AF increases with age. To date, there is no comprehensive review on aging-associated AF. In this review, we systematically discuss the pathophysiologic evidence for aging-associated AF, and in particular explore the pathophysiologic mechanisms of mitochondrial dysfunction, telomere attrition, cellular senescence, disabled macroautophagy, and gut dysbiosis involved in recent studies with aging-associated AF. We hope that by exploring the various dimensions of aging-associated AF, we can better understand the specific relationship between age and AF, which may be crucial for innovative treatments of aging-associated AF.

Cardioneuroablation for the management of neurally mediated syncope, sinus bradycardia, and atrioventricular block

Through several decades of medical advances, we have improved our understanding of the role of the autonomic nervous system in the production of a myriad of clinical cardiac conditions such as vasovagal syncope, situational syncope, carotid sinus hypersensitivity, vagally mediated sinus bradycardia, and atrioventricular block. While typically not associated with mortality, these common clinical entities may result in significant patient symptoms and morbidity and are often characterized by a frustrating treatment course with a paucity of effective strategies. In recent years, there has been increased interest in the management of these conditions via direct modulation of the parasympathetic component of the autonomic nervous system. This is achieved by targeting the ganglionated plexus central to the pathogenesis of these conditions via cardioneuroablation. The primary role of this strategy is evolving and serves to augment traditional treatment strategies such as lifestyle modification and pharmacotherapy. In this review, we examine the principles governing the role of cardioneuroablation in select populations with vasovagal syncope, sinus dysfunction, and atrioventricular block including the evolving evidence in this exciting field while keeping in mind the need for robust clinical studies examining the long-term effectiveness and safety.

Neurocardiology: translational advancements and potential

In our original white paper published in the The Journal of Physiology in 2016, we set out our knowledge of the structural and functional organization of cardiac autonomic control, how it remodels during disease, and approaches to exploit such knowledge for autonomic regulation therapy. The aim of this update is to build on this original blueprint, highlighting the significant progress which has been made in the field since and major challenges and opportunities that exist with regard to translation. Imbalances in autonomic responses, while beneficial in the short term, ultimately contribute to the evolution of cardiac pathology. As our understanding emerges of where and how to target in terms of actuators (including the heart and intracardiac nervous system (ICNS), stellate ganglia, dorsal root ganglia (DRG), vagus nerve, brainstem, and even higher centres), there is also a need to develop sensor technology to respond to appropriate biomarkers (electrophysiological, mechanical, and molecular) such that closed-loop autonomic regulation therapies can evolve. The goal is to work with endogenous control systems, rather than in opposition to them, to improve outcomes.

Oxidative stress and atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice. Though the pathogenesis of AF is complex and is not completely understood, many studies suggest that oxidative stress is a major mechanism in pathophysiology of AF. Through multiple mechanisms, reactive oxygen species (ROS) lead to the formation of an AF substrate that facilitates the development and maintenance of AF. In this review article, we provide an update on the different mechanisms by which oxidative stress promotes atrial remodeling. We then discuss several therapeutic strategies targeting oxidative stress for the prevention or treatment of AF. Considering the complex biology of ROS induced remodeling, and the evolution of ROS sources and compartmentalization during AF progression, there is a definite need for improvement in timing, targeting and reduction of off-target effects of therapeutic strategies targeting oxidative injury in AF.

The Role of Sodium Glucose Co-Transporter 2 Inhibitors in Atrial Fibrillation: A Comprehensive Review

Atrial fibrillation (AF) is the most prevalent arrhythmia among adults worldwide, frequently co-occurring with comorbidities such as Heart Failure (HF) and Type 2 Diabetes Mellitus (T2DM). This association contributes to increased morbidity and mortality, elevated healthcare costs, and diminished quality of life. Consequently, preventing or delaying the onset and recurrence of AF is crucial for reducing the incidence of complications. Sodium-glucose cotransporter 2 inhibitors (SGLT2is), due to their multifaceted pharmacological actions, have been proposed as potential therapeutic agents in the management of AF. However, current evidence from both animal models and clinical studies remains inconclusive. This narrative literature review aims to provide a comprehensive analysis of existing evidence on the impact of SGLT2is on the prevalence, incidence of new-onset, and recurrence of AF in diabetic populations and patients with HF. Numerous observational studies, predominantly retrospective, suggest a consistent reduction in AF risk with SGLT2is, while randomized controlled trials (RCTs) have yielded mixed results, with some demonstrating benefits and others not reaching statistical significance. The heterogeneity in study outcomes, population characteristics, follow-up duration, and specific SGLT2is used, as well as potential biases, underscore the need for further extensive and rigorous RCTs to establish definitive conclusions and elucidate the underlying mechanisms.

Stellate ganglion, inflammation, and arrhythmias: a new perspective on neuroimmune regulation

Current research on the stellate ganglion (SG) has shifted from merely understanding its role as a collection of neurons to recognizing its importance in immune regulation. As part of the autonomic nervous system (ANS), the SG plays a crucial role in regulating cardiovascular function, particularly cardiac sympathetic nerve activity. Abnormal SG function can lead to disordered cardiac electrical activity, which in turn affects heart rhythm stability. Studies have shown that excessive activity of the SG is closely related to the occurrence of arrhythmias, especially in the context of inflammation. Abnormal activity of the SG may trigger excessive excitation of the sympathetic nervous system (SNS) through neuroimmune mechanisms, thereby increasing the risk of arrhythmias. Simultaneously, the inflammatory response of the SG further aggravates this process, forming a vicious cycle. However, the causal relationship between SG, inflammation, and arrhythmias has not yet been fully clarified. Therefore, this article deeply explores the key role of the SG in arrhythmias and its complex relationship with inflammation, providing relevant clinical evidence. It indicates that interventions targeting SG function and inflammatory responses have potential in preventing and treating inflammation-related arrhythmias, offering a new perspective for cardiovascular disease treatment strategies.

Dysfunction of the autonomic nervous system in gastro-esophageal reflux disease: Consequences for the cardiovascular system

OBJECTIVE

The pathophysiology of gastro esophageal reflux disease (GERD) implicates autonomic dysregulation of the lower esophageal sphincter tone. Our goal is to investigate whether this dysregulation of the autonomic nervous system (ANS) function observed in isolated GERD cases can affect other systems, such as cardiovascular regulation.

METHODS

Twenty-five participants were included in the study, 11 patients with isolated GERD and 14 controls. All patients and 7 controls responded to a COMposite Autonomic Symptoms Score 31 (COMPASS 31) questionnaire and underwent functional explorations including EMLA test, sympathetic skin response (SSR), 24-hour heart rate recording and ambulatory blood pressure measurement (ABPM). Seven additional controls underwent a 24-hour heart rate recording only.

RESULTS

GERD patients (Age: mean 36.81±7.82; SR= 0.22) showed high clinically dysautonomic scores (COMPASS 31) (p = 0.015), increased Heart rate variability (HRV) parameters (daytime, nighttime, 24-hour SDNN (standard deviation of the RR interval (NN)), respectively p = 0.003, p < 0.001, p = 0.001; daytime and nighttime very low frequencies (VLF) respectively p = 0.03 and p = 0.007), impaired nocturnal dipping of blood pressure (3/11 patients) and high positivity of EMLA test (7/11, p = 0.037). These outcomes were strongly correlated with clinical dysautonomic assessment. No difference was observed between patients and controls regarding SSR.

CONCLUSION

Our data suggests a high parasympathetic tone amongst patients with GERD and a dysregulation of parasympathetic and sympathetic balance in the cardiovascular system with an impairment of the peripheral sympathetic fibers of cutaneous microcirculation, assessed by the EMLA test. GERD may be an inaugural symptom of autonomic neuropathy. Further functional exploration of peripheral small fibers seems to be necessary.

Potential Mechanisms of Epicardial Adipose Tissue Influencing Heart Failure with Preserved Ejection Fraction

Heart failure (HF) is the predominant terminal stage and the leading cause of mortality in cardiac disease. Heart failure with preserved ejection fraction (HFpEF) affects roughly 50% of HF patients globally. Due to the global aging population, the prevalence, morbidity, and mortality of HFpEF have gradually increased. Epicardial adipose tissue (EAT), as a key visceral adipose tissue around the heart, affects cardiac diastolic function and exercise reserve capacity. EAT closely adheres to the myocardium and can produce inflammatory factors, neurotransmitters, and other factors through autocrine or paracrine mechanisms, affecting the heart function by inflammatory response, cardiac metabolism and energy supply, cardiomyocyte structure and electrical activity, and pericardial vascular function. Currently, research on the mechanism and treatment methods of HFpEF is constantly improving. EAT may play a multi-level impact on the occurrence and development of HFpEF. This review also summarizes the potential impact of EAT on the heart in HFpEF combined with other metabolism-related diseases such as obesity or diabetes over other obesity-related measures, such as body mass index (BMI) or other adipose tissue. Above all, this review comprehensively summarizes the potential mechanisms by which EAT may affect HFpEF. The objective is to enhance our comprehension and management of HFpEF. Future research should delve into the mechanistic relationship between EAT and HFpEF, and investigate interventions aimed at EAT to improve the prognosis of patients with HFpEF.

Subjective identification and ablation of drivers improves rhythm control in patients with persistent atrial fibrillation. The CHAOS-AF study

INTRODUCTION AND OBJECTIVES

The optimal approach for persistent atrial fibrillation (AF) ablation remains unknown. In patients with persistent AF, we compared an ablation strategy based on pulmonary vein isolation (PVI) plus ablation of drivers (PVI+D), with a conventional PVI-only approach performed in a 1:1 propensity score-matched cohort.

METHODS

Drivers were subjectively identified using conventional high-density mapping catheters (IntellaMap ORION, PentaRay NAV or Advisor HD Grid), without dedicated software, as fractionated continuous or quasicontinuous electrograms on 1 to 2 adjacent bipoles, which were ablated first; and as sites with spatiotemporal dispersion (the entire cycle length comprised within the mapping catheter) plus noncontinuous fractionation, which were only targeted in patients without fractionated continuous electrograms, or without AF conversion after ablation of fractionated continuous electrograms. Ablation included PVI plus focal or linear ablation targeting drivers.

RESULTS

A total of 50 patients were included in each group (61±10 years, 25% women). Fractionated continuous electrograms were found and ablated in 21 patients from the PVI+D group (42%), leading to AF conversion in 7 patients. In the remaining 43 patients, 143 sites with spatiotemporal dispersion plus noncontinuous fractionation were targeted. Globally, AF conversion was achieved in 21 patients (42%). The PVI+D group showed lower atrial arrhythmia recurrences at 1 year of follow-up (30.6% vs 48%; P=.048) and at the last follow-up (46% vs 72%; P=.013), and less progression to permanent AF (10% vs 40%; P=.001).

CONCLUSIONS

Subjective identification and ablation of drivers, added to PVI, increased 1-year freedom from atrial arrhythmia and decreased long-term recurrences and progression to permanent AF.

Non-invasive Neuromodulation of Arrhythmias

The autonomic nervous system plays a central role in the pathogenesis of arrhythmias. Preclinical and clinical studies have demonstrated the therapeutic effect of neuromodulation at multiple anatomic targets across the neurocardiac axis for the treatment of arrhythmias. In this review, we discuss the rationale and clinical application of noninvasive neuromodulation techniques in treating arrhythmias and explore associated barriers and future directions, including optimization of stimulation parameters and patient selection.

Pathophysiologic Mechanisms in Cardiac Autonomic Nervous System and Arrhythmias

The autonomic nervous system, including the central nervous system and the cardiac plexus, maintains cardiac physiology. In diseased states, autonomic changes through neuronal remodeling generate electrical mechanisms of arrhythmia such as triggered activity or increased automaticity. This article will focus on the pathophysiological mechanisms of arrhythmia to highlight the role of the autonomic nervous system in disease and the related therapeutic interventions.

Sleep patterns and risk of chronic disease as measured by long-term monitoring with commercial wearable devices in the All of Us Research Program

Poor sleep health is associated with increased all-cause mortality and incidence of many chronic conditions. Previous studies have relied on cross-sectional and self-reported survey data or polysomnograms, which have limitations with respect to data granularity, sample size and longitudinal information. Here, using objectively measured, longitudinal sleep data from commercial wearable devices linked to electronic health record data from the All of Us Research Program, we show that sleep patterns, including sleep stages, duration and regularity, are associated with chronic disease incidence. Of the 6,785 participants included in this study, 71% were female, 84% self-identified as white and 71% had a college degree; the median age was 50.2 years (interquartile range = 35.7, 61.5) and the median sleep monitoring period was 4.5 years (2.5, 6.5). We found that rapid eye movement sleep and deep sleep were inversely associated with the odds of incident atrial fibrillation and that increased sleep irregularity was associated with increased odds of incident obesity, hyperlipidemia, hypertension, major depressive disorder and generalized anxiety disorder. Moreover, J-shaped associations were observed between average daily sleep duration and hypertension, major depressive disorder and generalized anxiety disorder. These findings show that sleep stages, duration and regularity are all important factors associated with chronic disease development and may inform evidence-based recommendations on healthy sleeping habits.

The Role of the Autonomic Nervous System as Both "Trigger and "Substrate" in Atrial Fibrillation

Several complex mechanisms, working alone, or together, initiate and maintain atrial fibrillation (AF). At disease onset, pulmonary vein-atrial triggers, producing ectopy, predominate. Then, as AF progresses, a shift toward substrate occurs, which AF also self-perpetuates. The autonomic nervous system (ANS) plays an important role as trigger and substrate. Although the efferent arm of the ANS as AF trigger is well-established, there is emerging evidence to show that (1) the ANS is a substrate for AF and (2) afferent or regulatory ANS dysfunction occurs in AF patients. These findings could represent a mechanism for the progression of AF.

Novel insight into neurofilament light chain and rhythm outcomes after catheter ablation of new-onset atrial fibrillation: A prospective cohort study

BACKGROUND

Atrial fibrillation (AF) is an age-related disorder closely linked to autonomic nervous system dysfunction. Neurofilament light chain (NFL) protein is a biomarker for neurodegenerative diseases.

OBJECTIVE

The purpose of this study was to evaluate the predictive value of NFL in forecasting AF recurrence after ablation.

METHODS

Patients newly diagnosed with AF who underwent catheter ablation were included. Serum NFL levels were measured using enzyme-linked immunosorbent assay. The primary outcome was AF recurrence during follow-up.

RESULTS

A total of 215 consecutive patients were enrolled, with average follow-up period of 10.69 months. During this period, 29 patients experienced AF recurrence. Multivariate Cox regression analysis revealed that high NFL levels (≥300 pg/mL) were an independent predictor of recurrence risk (adjusted hazard ratio [HR] 3.756; 95% confidence interval [CI] 1.392-10.136). The associations between NFL levels and AF recurrence were consistent across subgroups defined by age (>65 years), gender, hypertension, and paroxysmal AF. Restricted cubic spline analysis showed a consistent linear relationship across the entire range of NFL levels. Furthermore, incorporating NFL into the CHA2DS2-VASc score model significantly improved the prediction of recurrent AF risk, as demonstrated by time-dependent area under the curve and decision curve analysis. Notable enhancements were also observed in terms of net reclassification improvement (HR 0.464; 95% CI 0.226-0.675; P <.05) and integrated discrimination improvement (HR 0.087; 95% CI 0.017-0.183; P = .08).

CONCLUSION

NFL may serve as an effective biomarker for risk stratification and therapeutic decision-making in patients with new-onset AF who have undergone catheter ablation.

Meta-analysis of Pulsed Field Ablation Versus Thermal Ablation for Pulmonary Vein Isolation in AF: A Broad Overview Focusing on Efficacy, Safety and Outcomes

The recently established non-thermal, single-shot pulsed field ablation (PFA) is a potential tool for achieving rapid pulmonary vein isolation (PVI) to cause cell death by electroporation, yet data regarding this state-of-the-art technology remain sparse. In this meta-analysis, we included 3,857 patients from 20 studies. There was no significant difference in AF recurrence between the PFA and control groups. Subgroup analysis showed that additional ablation beyond PVI has a similar rate of AF recurrence to PVI alone (10% versus 13%, respectively). PVI durability was achieved in 83% (mean), 95% CI [65-99%] of the PFA group and in 79% (mean), 95% CI [60-98%] of the control group, with no significant difference in the rate of PVI durability between the two groups. The PFA group had considerably reduced procedure duration, but not fluoroscopy time. No statistically significant differences in periprocedural complications were observed. PFA is associated with shorter procedural time than thermal ablation. Cardiac complications were uncommon and mainly reversible in both the PFA and control groups.

A Need to Preserve Ejection Fraction during Heart Failure

Heart failure (HF) is a significant global healthcare burden with increasing prevalence and high morbidity and mortality rates. The diagnosis and management of HF are closely tied to ejection fraction (EF), a crucial parameter for evaluating disease severity and determining treatment plans. This paper emphasizes the urgent need to maintain EF during heart failure, highlighting the distinct phenotypes of HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF). It discusses the complexities of HFrEF pathophysiology and its negative impact on patient outcomes, stressing the importance of ongoing research and the development of effective therapeutic interventions to slow down the progression from preserved to reduced ejection fraction. Additionally, it explores the potential role of renal denervation in preserving ejection fraction and its implications for HFrEF management. This comprehensive review aims to offer valuable insights into the critical role of EF preservation in enhancing outcomes for patients with heart failure.

Dietary interventions in the management of atrial fibrillation

Atrial fibrillation (AF) represents the most common cardiac arrhythmia with significant morbidity and mortality implications. It is a common cause of hospital admissions, significantly impacts quality of life, increases morbidity and decreases life expectancy. Despite advancements in treatment options, prevalence of AF remains exceptionally high. AF is a challenging disease to manage, not just clinically but also financially. Evidence suggests lifestyle modification, including dietary changes, plays a significant role in the treatment of AF. This review aims to analyze the existing literature on the effects of dietary modifications on the incidence, progression, and outcomes of atrial fibrillation. It examines various dietary components, including alcohol, caffeine, omega-3 polyunsaturated fatty acids and minerals, and their impact on AF incidence, progression, and outcomes. The evidence surrounding the effects of dietary patterns, such as the Mediterranean and low carbohydrate diets, on AF is also evaluated. Overall, this review underscores the importance of dietary interventions as part of a comprehensive approach to AF management and highlights the need for further research in this emerging field.

Elevated liver fibrosis-4 index predicts recurrence after catheter ablation for atrial fibrillation in patients with heart failure

BACKGROUND

The fibrosis-4 (FIB-4) index is a noninvasive scoring system that is used to assess the progression of liver fibrosis. This study aimed to assess whether the FIB-4 index is associated with recurrent atrial fibrillation (AF) after catheter ablation in patients with and without heart failure (HF).

METHODS

We included 1,184 patients who underwent initial AF catheter ablation between 2016 and 2021. The patients were classified into low-risk (< 1.3), intermediate-risk (1.3-2.67), and high-risk (> 2.67) groups based on their FIB-4 indices at baseline. The patients were divided into HF (n = 552) and non-HF groups (n = 632); the HF group was further divided into paroxysmal AF (PAF) and non-PAF groups. AF recurrence after catheter ablation was then compared among the groups.

RESULTS

In the non-HF group, no significant differences in recurrence after ablation were observed between the low-(n = 219), intermediate-(n = 364), and high-risk (n = 49) groups. In contrast, in the HF group, the intermediate-(n = 341) and high-risk (n = 112) groups had significantly higher recurrence rates than the low-risk group (n = 99) (log-rank test, p = 0.005). This association remained significant after multivariate analysis (hazard ratio [HR]:1.374; p = 0.027). The FIB-4 index increased incrementally as the brain natriuretic peptide levels and severity of tricuspid regurgitation increased. The FIB-4 index was an independent predictor of recurrence in the non-PAF HF group (HR:1.498; p = 0.007) but not in the PAF group.

CONCLUSIONS

The FIB-4 index may be a useful predictor of AF recurrence after catheter ablation in patients with HF, particularly in those with non-PAF.

The impact of lifestyle factors on atrial fibrillation

Atrial fibrillation (AF), with its significant associated morbidity and mortality contributes to significant healthcare utilisation and expenditure. Given its progressively rising incidence, strategies to limit AF development and progression are urgently needed. Lifestyle modification is a potentially potent but underutilised weapon against the AF epidemic. The purpose of this article is to review the role of lifestyle factors as risk factors for AF, outline potential mechanisms of pathogenesis and examine the available evidence for lifestyle intervention in primary and secondary AF prevention. It will also highlight the need for investment by physicians, researchers, health services and governments in order to facilitate delivery of the comprehensive, multidisciplinary AF care that is required to manage this complex and multifactorial disease.

Impact of optimized transcutaneous auricular vagus nerve stimulation on cardiac autonomic profile in healthy subjects and heart failure patients

Objective.To determine the optimal frequency and site of stimulation for transcutaneous vagus nerve stimulation (tVNS) to induce acute changes in the autonomic profile (heart rate (HR), heart rate variability (HRV)) in healthy subjects (HS) and patients with heart failure (HF).Approach.We designed three single-blind, randomized, cross-over studies: (1) to compare the acute effect of left tVNS at 25 Hz and 10 Hz (n= 29, age 60 ± 7 years), (2) to compare the acute effect of left and right tVNS at the best frequency identified in study 1 (n= 28 age 61 ± 7 years), and (3) to compare the acute effect of the identified optimal stimulation protocol with sham stimulation in HS and HF patients (n= 30, age 59 ± 5 years, andn= 32, age 63 ± 7 years, respectively).Main results.In study 1, left tragus stimulation at 25 Hz was more effective than stimulation at 10 Hz in decreasing HR (-1.0 ± 1.2 bpm,p< 0.001 and -0.5 ± 1.6 bpm, respectively) and inducing vagal effects (significant increase in RMSSD, and HF power). In study 2, the HR reduction was greater with left than right tragus stimulation (-0.9 ± 1.5 bpm,p< 0.01 and -0.3 ± 1.4 bpm, respectively). In study 3 in HS, left tVNS at 25 Hz significantly reduced HR, whereas sham stimulation did not (-1.1 ± 1.2 bpm,p< 0.01 and -0.2 ± 2.9 bpm, respectively). In HF patients, both active and sham stimulation produced negligible effects.Significance.Left tVNS at 25 Hz is effective in acute modulation of cardiovascular autonomic control (HR, HRV) in HS but not in HF patients (NCT05789147).

Research Progress of Vagal Nerve Regulation Mechanism in Acupuncture Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. It has a high prevalence and poor prognosis. The application of antiarrhythmic drugs and even surgery cannot completely treat the disease, and there are many sequelae. AF can be classified into the category of "palpitation" in Chinese medicine according to its symptoms. Acupuncture has a significant effect on AF. The authors find that an important mechanism of acupuncture in AF treatment is to regulate the cardiac vagus nerve. Therefore, this article intends to review the distribution and function of vagus nerve in the heart, the application and the regulatroy effect for the treatment of AF.

Chronic Partial Sleep Deprivation Increased the Incidence of Atrial Fibrillation by Promoting Pulmonary Vein and Atrial Arrhythmogenesis in a Rodent Model

Sleep deprivation (SD) is a recognized risk factor for atrial fibrillation (AF), yet the precise molecular and electrophysiological mechanisms behind SD-induced AF are unclear. This study explores the electrical and structural changes that contribute to AF in chronic partial SD. We induced chronic partial SD in Wistar rats using a modified multiple-platform method. Echocardiography demonstrated impaired systolic and diastolic function in the left ventricle (LV) of the SD rats. The SD rats exhibited an elevated heart rate and a higher low-frequency to high-frequency ratio in a heart-rate variability analysis. Rapid transesophageal atrial pacing led to a higher incidence of AF and longer mean AF durations in the SD rats. Conventional microelectrode recordings showed accelerated pulmonary vein (PV) spontaneous activity in SD rats, along with a heightened occurrence of delayed after-depolarizations in the PV and left atrium (LA) induced by tachypacing and isoproterenol. A Western blot analysis showed reduced expression of G protein-coupled receptor kinase 2 (GRK2) in the LA of the SD rats. Chronic partial SD impairs LV function, promotes AF genesis, and increases PV and LA arrhythmogenesis, potentially attributed to sympathetic overactivity and reduced GRK2 expression. Targeting GRK2 signaling may offer promising therapeutic avenues for managing chronic partial SD-induced AF. Future investigations are mandatory to investigate the dose-response relationship between SD and AF genesis.

"Close your eyes and relax": the role of hypnosis in reducing anxiety, and its implications for the prevention of cardiovascular diseases

Anxiety is the most common form of mental health disorder, affecting millions of people worldwide. Psychosocial interventions such as mindfulness and cognitive behavioral therapy (CBT) have been suggested as an effective treatment in the management of general anxiety and anxiety disorders, with emerging evidence also suggesting the effectiveness of hypnosis. Moreover, anxiety has shown to be linked to the onset and development of several cardiovascular diseases (CVD), which are the leading cause of global death. In this paper, we review the current literature to examine the role that anxiety has on the onset and development of CVD and summarize the current knowledge on the role that hypnosis and hypnotherapy have in reducing anxiety, also explaining how this can impact the cardiovascular system and the prevention of CVD. Review of the evidence suggests that hypnosis and hypnotherapy are effective in treating anxiety and may positively affect the heart and the cardiovascular system, reducing sympathetic activation and increasing parasympathetic tone, potentially preventing the onset of CVD related to increased sympathetic activation. However, further studies are required to further understand how hypnosis and hypnotherapy affect the cardiovascular system through investigation of the neurophysiological components of the hypnotic state and of the mind-body relationship. Healthcare systems should embed mental health screening in patients at risk of developing CVD as part of the clinical pathway and consider the role that hypnosis and hypnotherapy may play in the management of CVD.

Leisure-time physical activity and the incidence of atrial fibrillation in senior adults: a prospective cohort study

OBJECTIVE

Whether physical activity could reduce the risk of atrial fibrillation (AF) remains unclear. This study was to investigate the relationship of leisure-time physical activity (LTPA) with AF incidence among Chinese older adults.

METHODS

A total of 3253 participants aged ≥60 years from the Guangzhou Heart Study were successfully followed between March 2018 and September 2019. LTPA was assessed using a modified Global Physical Activity Questionnaire. AF was ascertained by 12-lead electrocardiograms, 24-hour single-lead Holter and clinical examination. The Cox proportional hazards model was used to the estimate hazard ratio (HR) and 95% confidence interval (CI) after adjustment for confounders, and the population-attributable fraction (PAF) was estimated.

RESULTS

A total of 76 (2.34%) new-onset cases of AF were identified during a median of 31.13 months of follow-up. After adjustment for confounders, subjects who had LTPA at least 10.0 metabolic equivalent (MET)-hours/week had a 55% lower risk of developing AF (HR: 0.45, 95%CI: 0.25-0.81), and at least 20 MET-hours/week reduced the risk by 45% (HR: 0.55, 95%CI: 0.34-0.92). At least 11% (PAF: 11%, 95%CI: 0%-20%) or 14% (PAF: 14%, 95%CI: 0%-26%) of AF cases could be avoided, respectively, if the subjects do LTPA at least 10 MET-hours/week or 20 MET-hours/week. A significant exposure-response trend was also observed between LTPA and AF risk (Plinear-trend = 0.002). For a specific LTPA, doing housework was associated with a 43% reduced risk, while engaging in ball games was associated with an increased risk.

CONCLUSION

This prospective cohort study indicated that a higher LTPA volume was associated with a lower AF risk in Chinese older adults.

Vagus nerve stimulation for cardiovascular diseases: Is there light at the end of the tunnel?

Autonomic dysfunction and chronic inflammation contribute to the pathogenesis and progression of several cardiovascular diseases (CVD), such as heart failure with preserved ejection fraction, atherosclerotic CVD, pulmonary arterial hypertension, and atrial fibrillation. The vagus nerve provides parasympathetic innervation to the heart, vessels, and lungs, and is also implicated in the neural control of inflammation through a neuroimmune pathway involving the spleen. Stimulation of the vagus nerve (VNS) can in principle restore autonomic balance and suppress inflammation, with potential therapeutic benefits in these diseases. Although VNS ameliorated CVD in several animal models, early human studies have demonstrated variable efficacy. The purpose of this review is to discuss the rationale behind the use of VNS in the treatment of CVD, to critically review animal and human studies of VNS in CVD, and to propose possible means to overcome the challenges in the clinical translation of VNS in CVD.

Association Between Sleep Duration and Atrial Fibrillation: A Narrative Review

Sleep duration is a substantial risk factor for several cardiovascular diseases, including atrial fibrillation (AF). Despite much research, the precise nature of the relationship between the amount of sleep and AF remains unclear. This narrative review explores the relationship between AF and sleep duration, looking at genetic, mechanistic, and epidemiological data to explain this association. A U-shaped association (nonlinear relationship or curvilinear association) between sleep duration and AF has been seen, where longer and shorter sleep duration, more or less than seven to eight hours, have been associated with increased AF risk. Multiple mechanisms such as autonomic dysfunction, inflammation, and structural atrial remodeling have been proposed linking sleep disturbances to AF. Moreover, confounding factors such as individual lifestyle, comorbidities, and sleep quality could affect this association. Additionally, the interpretation of study results is further impacted by methodological limitations, including self-reported sleep duration and observational study designs. It is imperative to comprehend the complex relationship between sleep duration and AF to develop effective preventive and therapeutic methods. The main goals of future research should focus on prospective cohort studies with objective sleep metrics, exploring the mechanistic pathways, and comprehensive confounder adjustments that link sleep disturbances to AF. In summary, addressing sleep disturbances may represent one of the novel approaches to AF prevention and management, with potential implications for improving cardiovascular health and reducing AF-related morbidity and mortality.

Pulmonary Veins Function as Echo Chambers in Persistent Atrial Fibrillation: Circuitous Re-Entry Generates Outgoing Wavefronts

BACKGROUND

Although the substrate in persistent atrial fibrillation (PeAF) is not limited to the pulmonary veins (PVs), PV isolation (PVI) remains the cornerstone ablation strategy.

OBJECTIVES

The aim of this study was to describe the mechanism of outgoing wavefronts (WFs) originating in the PV sleeves during PeAF.

METHODS

Eleven patients presenting for first-time PeAF ablation were recruited (mean age 63.1 ± 10.9 years, 91% men). A 64-electrode catheter (Constellation; 38 mm) was positioned within the PV under fluoroscopic guidance. An inverse mapping technique was used to reconstruct unipolar atrial electrograms on the PV surface, and the resulting phase maps were used to identify incoming and outgoing WFs at the PV junction and to classify focal and re-entrant activity within the PV sleeves.

RESULTS

During PeAF, the PVs gave rise to outgoing WFs with a frequency of 3.7 s-1 (Q1-Q3: 3.4-5.4 s-1) compared with 3.6 s-1 (Q1-Q3: 2.8-4.2 s-1) for incoming WFs. Circuitous macroscopic re-entry was the dominant mechanism driving outgoing WFs (frequency of re-entry 2.7 s-1 [Q1-Q3: 2.0-3.3 s-1] compared with focal activity 1.4 s-1 [Q1-Q3: 1.1-1.5 s-1]; P < 0.006). This was initiated by incoming WFs in 80% of cases. Consecutive focal activation from the same location was infrequent (10.0% ± 6.6%, n = 10). Rotors ≥360° were never observed. The median ratio (R) of outgoing to incoming WF frequency was 1.14 (Q1-Q3: 0.84-1.75), with R > 1 in 6 of 11 PVs.

CONCLUSIONS

Electric activity generated by PV sleeves during PeAF is due mainly to circuitous re-entry initiated by incoming waves, frequently with R > 1. That is, the PVs act less as drivers of atrial fibrillation than as "echo chambers" that sustain and amplify fibrillatory activity.

Oil and gas development exposure and atrial fibrillation exacerbation: a retrospective study of atrial fibrillation exacerbation using Colorado's all payer claims dataset

Introduction

Emerging risk factors for atrial fibrillation (AF) incidence and episodes (exacerbation), the most common and clinically significant cardiac arrhythmia, include air and noise pollution, both of which are emitted during oil and natural gas (O&G) well site development.

Methods

We evaluated AF exacerbation risk and proximity to O&G well site development by employing a novel data source and interrupted time-series design. We retrospectively followed 1,197 AF patients living within 1-mile of an O&G well site (at-risk of exposure) and 9,764 patients living >2 miles from any O&G well site (unexposed) for AF claims in Colorado's All Payer Claims Dataset before, during, and after O&G well site development. We calculated AF exacerbation risk with multi-failure survival analysis.

Results

The analysis of the total study population does not provide strong evidence of an association between AF exacerbation and proximity to O&G wells sites during (HR = 1.07, 95% CI: 0.94, 1.22) or after (HR = 1.01, 95% CI: 0.88, 1.16) development. However, AF exacerbation risk differed by patient age and sex. In patients >80 years living within 0.39 miles (2,059 feet) of O&G well site development, AF exacerbation risk increased by 83% (HR = 1.83, 95% CI: 1.25, 2.66) and emergency room visits for an AF event doubled (HR = 2.55, 95% CI: 1.50, 4.36) during development, with risk increasing with proximity. In female patients living within 0.39 miles of O&G well site development, AF exacerbation risk increased by 56% percent (95% CI: 1.13, 2.15) during development. AF exacerbation risk did not persist past the well development period. We did not observe increased AF exacerbation risk in younger or male patients.

Discussion

The prospect that proximity to O&G well site development, a significant noise and air pollution source, may increase AF exacerbation risk in older and female AF patients requires attention. These findings support appropriate patient education to help mitigate risk and development of mitigation strategies and regulations to protect the health of populations in O&G development regions.

Eicosapentaenoic Acid and the Outcomes in Older Patients Undergoing Atrial Fibrillation Ablation

BACKGROUND

A lower serum eicosapentaenoic acid (EPA) to arachidonic acid (AA) ratio (EPA/AA) level correlates with cardiovascular events. Nevertheless, elevated serum EPA levels increase the risk of new-onset atrial fibrillation (AF) in older patients. The relationship between the EPA/AA and outcomes post-AF ablation remains unclear. This study investigated the impact of the EPA/AA on AF recurrence and cardiovascular events after AF ablation in older patients.

METHODS AND RESULTS

This retrospective cohort study examined consecutive patients with AF aged ≥65 years who underwent a first-time AF ablation. We compared the 3-year AF recurrence and 5-year major adverse cardiovascular event (MACE) rates between patients divided into high and low EPA/AA levels defined as above and below the median EPA/AA value before ablation. MACE was defined as heart failure hospitalizations, strokes, coronary artery disease, major bleeding, and cardiovascular death. Among the 673 included patients, the median EPA/AA value was 0.35. Compared with the low EPA/AA group, the high EPA/AA group had a significantly higher cumulative incidence of AF recurrence (39.3% versus 27.6%; log-rank P=0.004) and lower cumulative incidence of MACE (13.8% versus 25.5%, log-rank P=0.021). A high EPA/AA level was determined as an independent predictor of AF recurrence (hazard ratio [HR], 1.75 95% CI, 1.24-2.49; P=0.002) and MACE (HR, 0.60 [95% CI, 0.36-0.99]; P=0.046).

CONCLUSIONS

The EPA/AA was associated with AF recurrence and MACE after ablation in patients with AF aged ≥65 years.

Revitalizing brain perfusion: Unveiling advancements through rhythm control strategies in atrial fibrillation-A systematic review

Background

Recent evidence suggests an elevated risk of cognitive impairment and dementia in individuals with atrial fibrillation (AF), irrespective of stroke occurrence. AF, known to reduce brain perfusion, particularly through silent cerebral ischemia, underscores the intricate relationship between cardiac and cerebral health. The heart plays a crucial role in supporting normal brain function, and rhythm control, a standard AF treatment, has demonstrated enhancements in brain perfusion. This systematic review aimed to examine published data concerning the influence of rhythm control on brain perfusion in patients with atrial fibrillation.

Methods

A systematic search for relevant studies was carried out in Scopus, PubMed, Cochrane Reviews, ProQuest, and EBSCOhost, spanning from their inception until April 30, 2023. Studies that specifically examined brain perfusion following any form of rhythm control in atrial fibrillation were included in the review.

Results

The review encompassed 10 studies involving 436 participants. Among these, six utilized electrical cardioversion for rhythm control. The majority (8 out of 10) demonstrated that restoring sinus rhythm markedly enhances brain perfusion. In one of the two remaining studies, notable improvement was observed specifically in a region closely linked to cognition. Additionally, both studies reporting data on the Mini-Mental State Examination (MMSE) showed a consistent and significant increase in scores following rhythm control.

Conclusion

Successful rhythm control in AF emerges as a significant contributor to enhanced brain perfusion, suggesting a potential therapeutic avenue for reducing cognitive impairment incidence. However, further validation through larger prospective studies and randomized trials is warranted.

Circulating neuropeptide Y as a biomarker in postoperative atrial fibrillation cases administered off-pump coronary bypass Graft surgery

Background and aims

Postoperative atrial fibrillation (POAF) is considered the most prevalent irregular heart rhythm after heart surgery. The cardiac autonomic nervous system significantly affects POAF, and neuropeptide Y (NPY), an abundant neuropeptide in the cardiovascular system, is involved in this autonomic regulation. The current work aimed to examine the potential association of NPY with POAF in individuals administered isolated off-pump coronary artery bypass grafting.

Methods

From January 1 to May 31, 2020, we examined consecutive cases administered successful isolated off-pump coronary artery bypass grafting with no previously diagnosed atrial fibrillation (AF). Clinical characteristics and plasma samples were collected before surgery. NPY was quantified by enzyme-linked immunosorbent assay (ELISA) in peripheral blood, and POAF cases were identified through a 7-day Holter monitoring.

Results

Among 120 cases with no previously diagnosed AF, 33 (27.5 %) developed POAF during hospitalization. Median NPY levels were markedly elevated in the POAF group in comparison with the sinus rhythm group (31.72 vs. 27.95, P = 0.014). Multivariable logistic regression analysis revealed age (OR = 1.135, 95%CI 1.054-1.223; P = 0.001), left atrial size (OR = 1.136, 95%CI 1.004-1.285; P = 0.043), and NPY levels in peripheral blood (OR = 1.055, 95%CI 1.002-1.111; p = 0.041) independently predicted POAF. Additionally, NPY levels were positively correlated with high-frequency (HF) (r = 0.2774, P = 0.0022) and low-frequency (LF) (r = 0.2095, P = 0.0217) components of heart rate variability.

Conclusion

In summary, this study demonstrates an association between elevated NPY levels in peripheral blood before surgery and POAF occurrence.

Molecular and cellular neurocardiology in heart disease

This paper updates and builds on a previous White Paper in this journal that some of us contributed to concerning the molecular and cellular basis of cardiac neurobiology of heart disease. Here we focus on recent findings that underpin cardiac autonomic development, novel intracellular pathways and neuroplasticity. Throughout we highlight unanswered questions and areas of controversy. Whilst some neurochemical pathways are already demonstrating prognostic viability in patients with heart failure, we also discuss the opportunity to better understand sympathetic impairment by using patient specific stem cells that provides pathophysiological contextualization to study 'disease in a dish'. Novel imaging techniques and spatial transcriptomics are also facilitating a road map for target discovery of molecular pathways that may form a therapeutic opportunity to treat cardiac dysautonomia.

Small Left Ventricle in Patients With Atrial Fibrillation Is Associated With Increased Cardiovascular Risk

BACKGROUND

It is still unclear whether small left ventricle (LV) is an adverse structural prognostic feature in patients with atrial fibrillation (AF).

OBJECTIVES

The purpose of this study was to evaluate the association between small LV and risk of cardiovascular events in AF population.

METHODS

From the China-AF registry, 7,764 patients with AF were enrolled and divided into groups with normal, small, and large LV size based on left ventricular end-diastolic dimension (LVEDD) measurement per the American Society of Echocardiography references. Cox models were used to assess the association between LV size or LVEDD with composite cardiovascular events (cardiovascular death, ischemic stroke or systemic embolism, or major bleeding).

RESULTS

There were 308 (4.0%) participants assessed with small LV who were older, with lower body mass and blood pressure, and fewer comorbidities, and 429 (5.5%) were identified with large LV. Compared with the normal LV group, small LV and large LV were significantly associated with higher incidence of composite cardiovascular events (adjusted HR [aHR]: 1.54 [95% CI: 1.07-2.20] for small LV; aHR: 1.36 [95% CI: 1.02-1.81] for large LV) and cardiovascular death (aHR: 1.94 [95% CI: 1.14-3.28] for small LV; aHR: 1.83 [95% CI: 1.24-2.69] for large LV). Small LV was also associated with increased risk of major bleeding [aHR: 2.21 [95% CI: 1.01-4.86]). A U-shaped relationship between LVEDD and composite cardiovascular events was identified (Pnonlinear < 0.001).

CONCLUSIONS

In a prospective AF cohort, small LV was independently associated with an increased risk of cardiovascular events, which needed consideration in risk stratification and management for patients with AF. (ChiCTR-OCH-13003729).

Autonomic neuronal modulations in cardiac arrhythmias: Current concepts and emerging therapies

The pathophysiology of atrial fibrillation and ventricular tachycardia that result in cardiac arrhythmias is related to the sustained complicated mechanisms of the autonomic nervous system. Atrial fibrillation is when the heart beats irregularly, and ventricular arrhythmias are rapid and inconsistent heart rhythms, which involves many factors including the autonomic nervous system. It's a complex topic that requires careful exploration. Cultivation of speculative knowledge on atrial fibrillation; the irregular rhythm of the heart and ventricular arrhythmias; rapid oscillating waves resulting from mistakenly inconsistent P waves, and the inclusion of an autonomic nervous system is an inconceivable approach toward clinical intricacies. Autonomic modulation, therefore, acquires new expansions and conceptions of appealing therapeutic intelligence to prevent cardiac arrhythmia. Notably, autonomic modulation uses the neural tissue's flexibility to cause remodeling and, hence, provide therapeutic effects. In addition, autonomic modulation techniques included stimulation of the vagus nerve and tragus, renal denervation, cardiac sympathetic denervation, and baroreceptor activation treatment. Strong preclinical evidence and early human studies support the annihilation of cardiac arrhythmias by sympathetic and parasympathetic systems to transmigrate the cardiac myocytes and myocardium as efficient determinants at the cellular and physiological levels. However, the goal of this study is to draw attention to these promising early pre-clinical and clinical arrhythmia treatment options that use autonomic modulation as a therapeutic modality to conquer the troublesome process of irregular heart movements. Additionally, we provide a summary of the numerous techniques for measuring autonomic tone such as heart rate oscillations and its association with cutaneous sympathetic nerve activity appear to be substitute indicators and predictors of the outcome of treatment.

Artificial-intelligence-based risk prediction and mechanism discovery for atrial fibrillation using heart beat-to-beat intervals

BACKGROUND

Early diagnosis of atrial fibrillation (AF) is important for preventing stroke and other complications. Predicting AF risk in advance can improve early diagnostic efficiency. Deep learning has been used for disease risk prediction; however, it lacks adherence to evidence-based medicine standards. Identifying the underlying mechanisms behind disease risk prediction is important and required.

METHODS

We developed an explainable deep learning model called HBBI-AI to predict AF risk using only heart beat-to-beat intervals (HBBIs) during sinus rhythm. We proposed a possible AF mechanism based on the model's explainability and verified this conjecture using confirmed AF risk factors while also examining new AF risk factors. Finally, we investigated the changes in clinicians' ability to predict AF risk using only HBBIs before and after learning the model's explainability.

FINDINGS

HBBI-AI consistently performed well across large in-house and external public datasets. HBBIs with large changes or extreme stability were critical predictors for increased AF risk, and the underlying cause was autonomic imbalance. We verified various AF risk factors and discovered that autonomic imbalance was associated with all these factors. Finally, cardiologists effectively understood and learned from these findings to improve their abilities in AF risk prediction.

CONCLUSIONS

HBBI-AI effectively predicted AF risk using only HBBI information through evaluating autonomic imbalance. Autonomic imbalance may play an important role in many risk factors of AF rather than in a limited number of risk factors.

FUNDING

This study was supported in part by the National Key R&D Program and the National Natural Science Foundation of China.

The key characteristics of cardiotoxicity for the pervasive pollutant phenanthrene

The key characteristic (KCs) framework has been used previously to assess the carcinogenicity and cardiotoxicity of various chemical and pharmacological agents. Here, the 12 KCs of cardiotoxicity are used to evaluate the previously reported cardiotoxicity of phenanthrene (Phe), a tricyclic polycyclic aromatic hydrocarbon (PAH), and major component of fossil fuel-derived air pollution. Phe is a semi-volatile pollutant existing in both the gas phase and particle phase through adsorption onto or into particulate matter (PM). Phe can translocate across the airways and gastrointestinal tract into the systemic circulation, enabling body-wide effects. Our evaluation based on a comprehensive literature review, indicates Phe exhibits 11 of the 12 KCs for cardiotoxicity. These include adverse effects on cardiac electromechanical performance, the vasculature and endothelium, immunomodulation and oxidative stress, and neuronal and endocrine control. Environmental agents that have similarly damaging effects on the cardiovascular system are heavily regulated and monitored, yet globally there is no air quality regulation specific for PAHs like Phe. Environmental monitoring of Phe is not the international standard with benzo[a]pyrene being frequently used as a proxy despite the two PAH species exhibiting significant differences in sources, concentration variations and toxic effects. The evidence summarised in this evaluation highlights the need to move away from proxied PAH measurements and develop a monitoring network capable of measuring Phe concentration. It also stresses the need to raise awareness amongst the medical community of the potential cardiovascular impact of PAH exposure. This will allow the production of mitigation strategies and possibly the development of new policies for the protection of the societal groups most vulnerable to cardiovascular disease.

The association between low serum calcium level and new-onset atrial fibrillation after coronary artery bypass grafting

OBJECTIVES

This study aims to investigate the relationship between serum calcium (SC) levels and the incidence of postoperative atrial fibrillation (POAF) in patients undergoing coronary artery bypass graft surgery.

METHODS

This retrospective, observational cohort study consecutively enrolled patients undergoing isolated coronary artery bypass grafting in Beijing Anzhen Hospital from January 2018 to December 2021. Patients with a previous history of atrial fibrillation or atrial flutter or requiring concomitant cardiac surgery were excluded. A logistic regression model was used to determine predictors of POAF. Multivariable adjustment, inverse probability of treatment weighting and propensity score matching were used to adjust for confounders. Moreover, we conducted univariable and multivariable logistic regression analyses on preoperative and postoperative SC and ionized SC levels.

RESULTS

The analysis encompassed 12 293 patients. The POAF rate was significantly higher in patients with low SC level than those without (1379 [33.9%] vs 2375 [28.9%], P < 0.001). Low SC level was associated with an increased odds ratio of POAF (odds ratio [95% confidence interval]: 1.27 [1.18-1.37], P < 0.001). Inverse probability of treatment weighting and propensity score matching analyses confirmed the results. The increased POAF rate in low SC level group still existed among subgroup analysis based on different age, sex, body mass index, hypertension, hyperlipidaemia, CHA2DS2-VASc and magnesium.

CONCLUSIONS

Low SC level indicates elevated POAF risk in patients undergoing isolated coronary artery bypass graft surgery even after the adjustment for age, sex, cardiovascular risk factors, echocardiographic parameters and laboratory markers.

Prognostic value of cardiac deceleration capacity in patients with atrial fibrillation after catheter ablation: A systematic review and meta-analysis

INTRODUCTION

Cather ablation (CA) is a well-recognized treatment alternative for atrial fibrillation (AF) patients despite more than 20% ablation-treated patients suffering from AF recurrence. The underlying mechanism of AF recurrence postablation is probably associated with high cardiac parasympathetic activity, which can be assessed with deceleration capacity (DC) of heart rate. Given that the relationship between DC and AF recurrence is still controversial, this systematic review and meta-analysis was performed to investigate the characteristics of DC in patients with and without AF recurrence, evaluating the prognostic value of DC in AF patients after CA.

METHODS

A literature search was systematically performed in the Embase, PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases until October 01, 2023. The observational studies reporting either the pre- and postablation DC in both recurrence and non-recurrence groups or the ratios based on DC for predicting AF recurrence were mainly included. Weighted mean differences (WMD) or odds ratios (OR) based on DC would be calculated with a random-effect model, if heterogeneity estimated with the I2 index and Q statistic was significant (I2 > 50% or p < .05); otherwise, a fixed-effect model would be utilized.

RESULTS

A total of eight observational studies involving 914 AF patients treated with radiofrequency or cryoballoon ablation were included in this study. Ablation-treated patients with AF recurrence had the higher DC postablation in relation to those without recurrence (WMD, 1.00; 95% confidence interval [CI], 0.33-1.67; p < .01), which was present up to 3 months of follow-up (WMD, 1.54; 95% CI, 1.11-1.96; p < .01), whereas there was no statistical significance in DC before ablation between recurrence and non-recurrence groups (WMD, 0.34; 95% CI, -0.12 to 0.79; p = .15). The high DC postablation was a risk factor for AF recurrence in ablation-treated patients (OR, 2.17; 95% CI, 1.44-3.25; p < .01).

CONCLUSION

The high DC postablation was associated with the risk of AF recurrence, suggesting that DC may act as a prognostic indicator in AF patients treated with CA.

Skin sympathetic nerve activity in different ablation settings for atrial fibrillation

BACKGROUND

Modifying the autonomic system after catheter ablation may prevent the recurrence of atrial fibrillation (AF). Evaluation of skin sympathetic nerve activity (SKNA) is a noninvasive method for the assessment of sympathetic activity. However, there are few studies on the effects of different energy settings on SKNA.

OBJECTIVE

To investigate the changes in SKNA in different energy settings and their relationship to AF ablation outcomes.

METHODS

Seventy-two patients with paroxysmal and persistent AF were enrolled. Forty-three patients received AF ablation with the conventional (ConV) energy setting (low power for long duration), and 29 patients using a high-power, short-duration (HPSD) strategy. The SKNA was acquired from the right arm 1 day before and after the radiofrequency ablation. We analyzed the SKNA and ablation outcomes in the different energy settings.

RESULTS

Both groups had a similar baseline average SKNA (aSKNA). We found that the median aSKNA increased significantly from 446.82 μV to 805.93 μV (p = 0.003) in the ConV group but not in the HPSD group. In the ConV group, patients without AF recurrence had higher aSKNA values. However, the 1-year AF recurrence rate remained similar between both groups (35 % vs. 28 %, p = 0.52).

CONCLUSION

The post-ablation aSKNA levels increased significantly in the ConV group but did not change significantly in the HPSD group, which may reflect different neuromodulatory effects. However, the one-year AF recurrence rates were similar for both groups. These results demonstrate that the HPSD strategy has durable lesion creation but less lesion depth, which may reduce collateral damage.

Electrophysiology and 3D-imaging reveal properties of human intracardiac neurons and increased excitability with atrial fibrillation

Altered autonomic input to the heart plays a major role in atrial fibrillation (AF). Autonomic neurons termed ganglionated plexi (GP) are clustered on the heart surface to provide the last point of neural control of cardiac function. To date the properties of GP neurons in humans are unknown. Here we have addressed this knowledge gap in human GP neuron structure and physiology in patients with and without AF. Human right atrial GP neurons embedded in epicardial adipose tissue were excised during open heart surgery performed on both non-AF and AF patients and then characterised physiologically by whole cell patch clamp techniques. Structural analysis was also performed after fixation at both the single cell and at the entire GP levels via three-dimensional confocal imaging. Human GP neurons were found to exhibit unique properties and structural complexity with branched neurite outgrowth. Significant differences in excitability were revealed between AF and non-AF GP neurons as measured by lower current to induce action potential firing, a reduced occurrence of low action potential firing rates, decreased accommodation and increased synaptic density. Visualisation of entire GPs showed almost all neurons are cholinergic with a small proportion of noradrenergic and dual phenotype neurons. Phenotypic distribution differences occurred with AF including decreased cholinergic and dual phenotype neurons, and increased noradrenergic neurons. These data show both functional and structural differences occur between GP neurons from patients with and without AF, highlighting that cellular plasticity occurs in neural input to the heart that could alter autonomic influence on atrial function. KEY POINTS: The autonomic nervous system plays a critical role in regulating heart rhythm and the initiation of AF; however, the structural and functional properties of human autonomic neurons in the autonomic ganglionated plexi (GP) remain unknown. Here we perform the first whole cell patch clamp electrophysiological and large tissue confocal imaging analysis of these neurons from patients with and without AF. Our data show human GP neurons are functionally and structurally complex. Measurements of action potential kinetics show higher excitability in GP neurons from AF patients as measured by lower current to induce action potential firing, reduced low firing action potential rates, and decreased action potential accommodation. Confocal imaging shows increased synaptic density and noradrenergic phenotypes in patients with AF. Both functional and structural differences occur in GP neurons from patients with AF that could alter autonomic influence on atrial rhythm.

The causal relationship between obesity, obstructive sleep apnea and atrial fibrillation: a study based on mediated Mendelian randomization

Background

Atrial fibrillation (AF) is a common cardiac arrhythmia that is associated with obesity and obstructive sleep apnea syndrome (OSA). Obesity and OSA may increase the risk of AF by affecting cardiovascular health.

Methods

The study used the Mendelian randomization (MR) approach, combined with two-sample and multivariable analyses, to assess the relationships between obesity, OSA, and AF. The study utilized GWAS data and applied various statistical methods for the analysis.

Results

The study found that obesity increased the risk of OSA, which in turn significantly increased the risk of AF. Through mediating MR analysis, it was found that OSA played a certain role in the causal relationship between obesity and AF, with about 6.4% of the risk of AF being mediated by OSA.

Conclusion

This study highlights the relationships among obesity, OSA, and AF, providing useful guidance for future clinical researches.

Emerging Role of Renal Sympathetic Denervation as an Adjunct Therapy to Atrial Fibrillation Ablation

The central anatomical locus in the context of atrial fibrillation (AF) ablation has been the pulmonary veins. Despite the attainment of a modest long-term success rate through pulmonary vein isolation (PVI), the pursuit of achieving a therapeutic efficacy nearing a definitive cure has spurred an investigation into alternative strategies and anatomical loci beyond the pulmonary veins. Despite extensive exploration, none of these alternative targets have succeeded in establishing themselves as routine ablation sites comparable to the pulmonary veins. Consequently, there exists an imperative for further inquiry and refinement of ablation strategies to propel advancements within the domain of AF ablation, thereby augmenting patient outcomes. Simultaneously, the examination of the autonomic system's role in AF pathophysiology introduces an additional ablation target aimed at rectifying sympathovagal imbalance. This discourse presents a contemporary review of renal denervation (RDN) as an emergent and auspicious technique poised to complement PVI, thereby contributing substantively to the augmentation of long-term success within the ambit of AF rhythm-control strategies.

Exploring the causal relationships and mediating factors between depression, anxiety, panic, and atrial fibrillation: A multivariable Mendelian randomization study

BACKGROUND

Atrial fibrillation is a significant cardiovascular disease, and the increased risk of its occurrence may be influenced by mental disorders. Currently, the causal relationship between them remains controversial. Our aim is to ascertain the relationship between atrial fibrillation and mental disorders including depression, anxiety, and panic, as well as the risk factors mediating this relationship, through the judgment of genetic susceptibility.

METHODS

We utilized the summarized statistics from nine large-scale genome-wide association studies (in European populations), including depression (PGC, N = 807,553), anxiety (FinnGen, N = 429,209), panic (PGC, N = 230,878), diabetes (UK Biobank, N = 655,666), smoking (IEU, 607,291), hypertension (UK biobank, N = 463,010), obstructive sleep apnea (IEU, N = 476,853), obesity (UK biobank, N = 463,010), and AF (IEU, N = 1,030,836). By applying bidirectional two-sample Mendelian randomization and multivariable Mendelian randomization to depression, anxiety, panic, and AF, we analyzed their causal relationships and the independent influence of specific risk factors. Furthermore, a two-step MR approach was used to assess the mediating effects of diabetes, smoking, hypertension, obstructive sleep apnea, and obesity.

RESULTS

Results from the Two-Sample Mendelian Randomization Inverse Variance Weighted Random Effects Model show: the occurrence of genetically predicted depression is related to an increased risk of atrial fibrillation (AF) (OR: 1.073; [95 % CI: 1.005-1.146] P < 0.05), and panic is more significantly associated than depression (OR: 1.017; [95 % CI: 1.008-1.027] P < 0.001), while anxiety has no causal relationship with the occurrence of AF (OR: 1.023; [95 % CI: 0.960-1.092], P > 0.05), and AF is not significantly related to the occurrence of depression, anxiety, or panic (P > 0.05). After correcting for the other two risk factors using multivariable Mendelian randomization, depression remains significantly related to the occurrence of AF (β: 0.075; 95 % CI: [0.006, 0.144], P < 0.05), while panic and anxiety are not related to the occurrence of AF. Among them, the risk factors for AF occurrence, hypertension and obesity, are mediators between depression and AF, with mediation proportions of 74.9 % and 14.3 %, respectively. The mediating effects of diabetes, smoking, and obstructive sleep apnea were found to be not statistically significant. The above results are robust after sensitivity analysis.

CONCLUSION

Our results identified that the genetic susceptibility to depression is an independent risk factor for the occurrence of AF, and that hypertension and obesity can mediate this process. Panic also poses some risk to the onset of AF. This demonstrates that controlling hypertension and obesity for emotional management is of great importance in preventing the occurrence of AF.

Use of Atrial Fibrillation Electrograms and T1/T2 Magnetic Resonance Imaging to Define the Progressive Nature of Molecular and Structural Remodeling: A New Paradigm Underlying the Emergence of Persistent Atrial Fibrillation

BACKGROUND

The temporal progression states of the molecular and structural substrate in atrial fibrillation (AF) are not well understood. We hypothesized that these can be detected by AF electrograms and magnetic resonance imaging parametric mapping.

METHODS AND RESULTS

AF was induced in 43 dogs (25-35 kg, ≥1 year) by rapid atrial pacing (RAP) (3-33 weeks, 600 beats/min), and 4 controls were used. We performed high-resolution epicardial mapping (UnEmap, 6 atrial regions, both atria, 130 electrodes, distance 2.5 mm) and analyzed electrogram cycle length, dominant frequency, organization index, and peak-to-peak bipolar voltage. Implantable telemetry recordings were used to quantify parasympathetic nerve activity over RAP time. Magnetic resonance imaging native T1, postcontrast T1, T2 mapping, and extracellular volume fraction were assessed (1.5T, Siemens) at baseline and AF. In explanted atrial tissue, DNA oxidative damage (8-hydroxy-2'-deoxyguanosine staining) and percentage of fibrofatty tissue were quantified. Cycle length and organization index decreased (R=0.5, P<0.05; and R=0.5, P<0.05; respectively), and dominant frequency increased (R=0.3, P n.s.) until 80 days of RAP but not thereafter. In contrast, voltage continued to decrease throughout the duration of RAP (R=0.6, P<0.05). Parasympathetic nerve activity increased following RAP and plateaued at 80 days. Magnetic resonance imaging native T1 and T2 times increased with RAP days (R=0.5, P<0.05; R=0.6, P<0.05) in the posterior left atrium throughout RAP. Increased RAP days correlated with increasing 8-hydroxy-2'-deoxyguanosine levels and with fibrosis percentage (R=0.5, P<0.05 for both).

CONCLUSIONS

A combination of AF electrogram characteristics and T1/T2 magnetic resonance imaging can detect early-stage AF remodeling (autonomic remodeling, oxidative stress) and advanced AF remodeling due to oxidative stress and fibrosis.

Device therapy for patients with atrial fibrillation and heart failure with preserved ejection fraction

Device therapy is a nonpharmacological approach that presents a crucial advancement for managing patients with atrial fibrillation (AF) and heart failure with preserved ejection fraction (HFpEF). This review investigated the impact of device-based interventions and emphasized their potential for optimizing treatment for this complex patient demographic. Cardiac resynchronization therapy, augmented by atrioventricular node ablation with His-bundle pacing or left bundle-branch pacing, is effective for enhancing cardiac function and establishing atrioventricular synchrony. Cardiac contractility modulation and vagus nerve stimulation represent novel strategies for increasing myocardial contractility and adjusting the autonomic balance. Left ventricular expanders have demonstrated short-term benefits in HFpEF patients but require more investigation for long-term effectiveness and safety, especially in patients with AF. Research gaps regarding complications arising from left ventricular expander implantation need to be addressed. Device-based therapies for heart valve diseases, such as transcatheter aortic valve replacement and transcatheter edge-to-edge repair, show promise for patients with AF and HFpEF, particularly those with mitral or tricuspid regurgitation. Clinical evaluations show that these device therapies lessen AF occurrence, improve exercise tolerance, and boost left ventricular diastolic function. However, additional studies are required to perfect patient selection criteria and ascertain the long-term effectiveness and safety of these interventions. Our review underscores the significant potential of device therapy for improving the outcomes and quality of life for patients with AF and HFpEF.

Interactions between calcium-induced arrhythmia triggers and the electrophysiological-anatomical substrate underlying the induction of atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is sustained by spontaneous focal excitations and re-entry. Spontaneous electrical firing in the pulmonary vein (PV) sleeves is implicated in AF generation. The aim of this simulation study was to identify the mechanisms determining the localisation of AF triggers in the PVs and their contribution to the genesis of AF. A novel biophysical model of the canine atria was used that integrates stochastic, spontaneous subcellular Ca2+ release events (SCRE) with regional electrophysiological heterogeneity in ionic properties and a detailed three-dimensional model of atrial anatomy, microarchitecture and patchy fibrosis. Simulations highlighted the importance of the smaller inward rectifier potassium current (IK1 ) in PV cells compared to the surrounding atria, which enabled SCRE more readily to result in delayed-afterdepolarisations that induced triggered activity. There was a leftward shift in the dependence of the probability of triggered activity on sarcoplasmic reticulum Ca2+ load. This feature was accentuated in 3D tissue compared to single cells (Δ half-maximal [Ca2+ ]SR  = 58 μM vs. 22 μM). In 3D atria incorporating electrical heterogeneity, excitations preferentially emerged from the PV region. These triggered focal excitations resulted in transient re-entry in the left atrium. Addition of fibrotic patches promoted localised emergence of focal excitations and wavebreaks that had a more substantial impact on generating AF-like patterns than the PVs. Thus, a reduced IK1 , less negative resting membrane potential, and fibrosis-induced changes of the electrotonic load all contribute to the emergence of complex excitation patterns from spontaneous focal triggers. KEY POINTS: Focal excitations in the atria are most commonly associated with the pulmonary veins, but the mechanisms for this localisation are yet to be elucidated. We applied a multi-scale computational modelling approach to elucidate the mechanisms underlying such localisations. Myocytes in the pulmonary vein region of the atria have a less negative resting membrane potential and reduced time-independent potassium current; we demonstrate that both of these factors promote triggered activity in single cells and tissues. The less negative resting membrane potential also contributes to heterogeneous inactivation of the fast sodium current, which can enable re-entrant-like excitation patterns to emerge without traditional conduction block.

Early Renal Denervation Attenuates Cardiac Dysfunction in Heart Failure With Preserved Ejection Fraction

BACKGROUND

The renal sympathetic nervous system modulates systemic blood pressure, cardiac performance, and renal function. Pathological increases in renal sympathetic nerve activity contribute to the pathogenesis of heart failure with preserved ejection fraction (HFpEF). We investigated the effects of renal sympathetic denervation performed at early or late stages of HFpEF progression.

METHODS AND RESULTS

Male ZSF1 obese rats were subjected to radiofrequency renal denervation (RF-RDN) or sham procedure at either 8 weeks or 20 weeks of age and assessed for cardiovascular function, exercise capacity, and cardiorenal fibrosis. Renal norepinephrine and renal nerve tyrosine hydroxylase staining were performed to quantify denervation following RF-RDN. In addition, renal injury, oxidative stress, inflammation, and profibrotic biomarkers were evaluated to determine pathways associated with RDN. RF-RDN significantly reduced renal norepinephrine and tyrosine hydroxylase content in both study cohorts. RF-RDN therapy performed at 8 weeks of age attenuated cardiac dysfunction, reduced cardiorenal fibrosis, and improved endothelial-dependent vascular reactivity. These improvements were associated with reductions in renal injury markers, expression of renal NLR family pyrin domain containing 3/interleukin 1β, and expression of profibrotic mediators. RF-RDN failed to exert beneficial effects when administered in the 20-week-old HFpEF cohort.

CONCLUSIONS

Our data demonstrate that early RF-RDN therapy protects against HFpEF disease progression in part due to the attenuation of renal fibrosis and inflammation. In contrast, the renoprotective and left ventricular functional improvements were lost when RF-RDN was performed in later HFpEF progression. These results suggest that RDN may be a viable treatment option for HFpEF during the early stages of this systemic inflammatory disease.

Effect of Low-Frequency Renal Nerve Stimulation on Renal Glucose Release during Normoglycemia and a Hypoglycemic Clamp in Pigs

Previously, we demonstrated that renal denervation in pigs reduces renal glucose release during a hypoglycemic episode. In this study we set out to examine changes in side-dependent renal net glucose release (SGN) through unilateral low-frequency stimulation (LFS) of the renal plexus with a pulse generator (2-5 Hz) during normoglycemia (60 min) and insulin-induced hypoglycemia ≤3.5 mmol/L (75 min) in seven pigs. The jugular vein, carotid artery, renal artery and vein, and both ureters were catheterized for measurement purposes, blood pressure management, and drug and fluid infusions. Para-aminohippurate (PAH) and inulin infusions were used to determine side-dependent renal plasma flow (SRP) and glomerular filtration rate (GFR). In a linear mixed model, LFS caused no change in SRP but decreased sodium excretion (p < 0.0001), as well as decreasing GFR during hypoglycemia (p = 0.0176). In a linear mixed model, only hypoglycemic conditions exerted significant effects on SGN (p = 0.001), whereas LFS did not. In a Wilcoxon signed rank exact test, LFS significantly increased SGN (p = 0.03125) and decreased sodium excretion (p = 0.0017) and urinary flow rate (p = 0.0129) when only considering the first instance LFS followed a preceding period of non-stimulation during normoglycemia. To conclude, this study represents, to our knowledge, the first description of an induction of renal gluconeogenesis by LFS.

Effects of menstrual disorders and dysmenorrhea on cardiovascular disease: a Mendelian randomization study

Background

Observational studies have demonstrated associations between menstrual disorders, dysmenorrhea, and cardiovascular disease (CVD). However, it remains unclear whether these associations are causal. This study is to investigate whether menstrual disorders and dysmenorrhea causally affect the risk of CVD.

Methods

The summary data for menstrual disorders (excessive menstruation and irregular menses) and dysmenorrhea were obtained from FinnGen study, summary data for CVD were obtained from UK Biobank and meta-analysis. The inverse-variance-weighted method was mainly used in the Mendelian randomization for causality analysis. Sensitivity analyses were performed by several methods under different model assumptions.

Results

Genetic liability to excessive menstruation was associated with higher risk of atrial fibrillation (odds ratio (OR), 1.078 [95% confidence interval (CI), 1.015-1.145]; P=0.014), but a lower risk of hypertension (OR, 0.994 [95% CI: 0.989-0.999]; P=0.016). Irregular menses was associated with higher risk of atrial fibrillation (OR, 1.095 [95% CI: 1.015-1.182]; P=0.02), hypertension (OR, 1.007 [95% CI: 1.000-1.013]; P=0.047), myocardial infarction (OR, 1.172 [95% CI: 1.060-1.295]; P=0.02), ischemic heart disease, (OR, 1.005 [95% CI: 1.000-1.010]; P=0.037) and coronary heart disease (OR, 1.004 [95% CI: 1.001-1.008]; P=0.026). Dysmenorrhea was associated with higher risk of atrial fibrillation (OR, 1.052 [95% CI: 1.014-1.092]; P=0.008) and Ischemic stroke (cardioembolic) (OR, 1.122 [95% CI: 1.002-1.257]; P=0.046). After Benjamini-Hochberg correction, irregular menses was associated with higher risk of myocardial infarction.

Conclusion

We confirmed a causal relationship of excessive menstruation, irregular menses and dysmenorrhea on cardiovascular outcomes independent of sex hormone levels, with an emphasis on the link between irregular menses and myocardial infarction. These clinical features can be utilized as markers to identify women at higher risk of developing CVD in the future, recommending early clinical intervention of menstrual diseases.