Sex differences in the electrophysiological characteristics of pulmonary veins and left atrium and their clinical implication in atrial fibrillation

Association Between Central Sleep Apnea and Left Atrial Enlargement in Snoring Patients with Preserved Ejection Fraction

Background

Central sleep apnea (CSA) significantly impacts cardiovascular health, linking it to left atrial enlargement, atrial fibrillation, and impaired cardiac function in heart failure patients with reduced ejection fraction (EF). However, the relationship between CSA and left atrial size in individuals with preserved EF remains underexplored.

Objective

This study aims to examine the relationship between left atrial size and CSA in snoring patients with preserved EF.

Methods

An observational study was conducted involving 341 consecutive snoring patients from a cardiology department who underwent overnight polysomnography (PSG) and echocardiography. Patients with EF below 50%, pulmonary diseases or neuromuscular disorders were excluded. CSA was defined as a central apnea-hypopnea index (CAHI) of five or more events per hour. Inverse probability of treatment weighting (IPTW) and logistic regression models were employed to evaluate the relationship between CSA and left atrial size.

Results

Among the 341 patients, 33 (9.68%) were diagnosed with CSA, with a higher prevalence in males (10.0%) than females (8.91%). Left atrial enlargement (LAE) was observed in 172 patients (50.44%), predominantly in females (71.29%). CSA patients demonstrated significantly higher apnea-hypopnea index (AHI) (49.2/h vs 26.75/h, p < 0.01) and oxygen desaturation index (ODI) (44.9 vs 22.85, p < 0.01), alongside more sleep time with oxygen saturation < 90% (6.6% vs 2.35%, p = 0.01). Echocardiographic evaluations revealed that CSA patients had a greater left atrial anterior-posterior diameter(LAD-ap 42.73 ± 13.01 mm vs 38.15 ± 4.58 mm, p < 0.01) and a higher frequency of LAE (69.7% vs 48.38%, p = 0.02). Males with CSA had a significantly increased risk of LAE (OR: 4.54; 95% CI: 1.45-14.2) after IPTW adjustment, with significant associations persisting among those with risk factors such as smoking and dyslipidemia.

Conclusion

This study highlights a significant association between CSA and left atrial enlargement in males with preserved EF, suggesting that CSA may contribute to atrial remodeling even without reduced ejection fraction.

Phosphodiesterase 10A Inhibitor Modulates Right Ventricular Outflow Tract Electrophysiological Activities and Calcium Homeostasis via the cGMP/PKG Pathway

Phosphodiesterase inhibitors regulate intracellular Ca2+ of cardiomyocytes through enhancing second messenger signalling. This study aimed to investigate whether TP-10, a selective phosphodiesterase10A inhibitor, modulates Ca2+ cycling, attenuating arrhythmogenesis in the right ventricular outflow tract (RVOT). Right ventricular tissues from New Zealand white rabbits were harvested, and electromechanical analyses of ventricular tissues were conducted. Intracellular Ca2+ was monitored using Fluo-3, and ionic current was recorded using patch-clamp in isolated cardiomyocytes. Tissues from RVOT exhibited a reduction in action potential duration at both 50% and 90% repolarisation following treatment with TP-10. This treatment also inhibited burst firing induced by isoproterenol (ISO) in RVOT tissues, an effect that was nullified by thapsigargin. The protein kinase G inhibitor KT5823, whether used alone or in conjunction with TP-10, also suppressed ISO-induced burst firing in these tissues. Compared to the control group, RVOT cardiomyocytes treated with TP-10 demonstrated enhanced amplitudes of Ca2+ transients and increased stores of Ca2+ in the sarcoplasmic reticulum. Although the L-type Ca2+ current was diminished in TP-10-treated cardiomyocytes, the current from the Na+-Ca2+ exchanger was elevated. Furthermore, the density of late Na+ current was significantly reduced in these treated cardiomyocytes. TP-10 administration also resulted in increased levels of calcium regulatory proteins, specifically phosphorylated phospholamban at Thr17 and sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2a. Our findings indicate that TP-10 attenuates ISO-induced arrhythmic events in RVOT tissues via cGMP-mediated modulation of intracellular Ca2+ regulation.

Male and female atria exhibit distinct acute electrophysiological responses to sex steroids

The electrophysiological properties of the hearts of women and men are different. These differences are at least partly mediated by the actions of circulating estrogens and androgens on the cardiomyocytes. Experimentally, much of our understanding in this field is based on studies focusing on ventricular tissue, with considerably less known in the context of atrial electrophysiology. The aim of this investigation was to compare the electrophysiological properties of male and female atria and assess responses to acute sex steroid exposure. Age-matched adult male and female C57BL/6 mice were anesthetized (4 % isoflurane) and left atria isolated. Atria were loaded with Di-4-ANEPPS voltage sensitive dye and optical mapping performed to assess action potential duration (APD; at 10 %, 20 %, 30 %, 50 %, and 70 % repolarization) and conduction velocity in the presence of 1 nM and 100 nM 17β-estradiol or testosterone. Male and female left atria demonstrated similar baseline action potential duration and conduction velocity, with significantly greater APD70 spatial heterogeneity evident in females. 17β-estradiol prolonged action potential duration in both sexes - an effect that was augmented in females. Atrial conduction was slowed in the presence of 100 nM 17β-estradiol in both males and females. Testosterone prolonged action potential duration in males only and did not modulate conduction velocity in either sex. This study provides novel insights into male and female atrial electrophysiology and its regulation by sex steroids. As systemic sex steroid levels change and intra-cardiac estrogen synthesis capacity increases with aging, these actions may have an increasingly important role in determining atrial arrhythmia vulnerability.

Sex Differences in the Relationship Between Self-Reporting of Snoring and Cardiovascular Risk:An Analysis of NHANES

Background

Identifying risk factors for cardiovascular disease (CVD) is critical for effective prevention and management. While classic CVD risk factors have been extensively studied, there is a scarcity of research on the association between snoring and CVD risk, particularly in the context of sex differences.

Methods

This study utilized data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2015 and 2020. Participants were initially categorized based on the severity of snoring or the presence of snoring.Within the snoring group, they were further classified by sex. Analysis was carried out using multivariate logistic regression.

Results

Our study included 12,681 participants aged 18 years or older. When compared to the non-snoring group, individuals in the moderate snoring group had a higher odds ratio (OR) of 1.418 (95% CI 1.083 to 1.857, p = 0.011), while those in the severe snoring group had a higher OR of 1.882 (95% CI 1.468 to 2.409, p < 0.001). In the snoring group, individuals were further categorized by gender: 4527 males and 4131 females. Importantly, male patients showed a higher OR for atrial fibrillation (4.945, 95% CI 1.187 to 20.598, p = 0.028) compared to females. Additionally, male patients had a higher OR for coronary heart disease (2.002, 95% CI 1.152 to 3.479, p = 0.014) compared to females.

Conclusion

Sex plays a significant role in the relationship between snoring and CVD risk. Males with snoring have a higher risk of developing CVD compared to females. In particular, male snorers are nearly five times more likely to develop atrial fibrillation and about twice as likely to experience coronary artery disease in comparison to female snorers. It is recommended that healthcare providers and public health officials prioritize cardiovascular risk assessments for male individuals who exhibit symptoms of snoring.

Effects of Sex on the Susceptibility for Atrial Fibrillation in Pigs with Ischemic Heart Failure

Atrial fibrillation (AF) is the most prevalent arrhythmia, often caused by myocardial ischemia/infarction (MI). Men have a 1.5× higher prevalence of AF, whereas women show a higher risk for new onset AF after MI. However, the underlying mechanisms of how sex affects AF pathophysiology are largely unknown. In 72 pigs with/without ischemic heart failure (IHF) we investigated the impact of sex on ischemia-induced proarrhythmic atrial remodeling and the susceptibility for AF. Electrocardiogram (ECG) and electrophysiological studies were conducted to assess electrical remodeling; histological analyses were performed to assess atrial fibrosis in male and female pigs. IHF pigs of both sexes showed a significantly increased vulnerability for AF, but in male pigs more and longer episodes were observed. Unchanged conduction properties but enhanced left atrial fibrosis indicated structural rather than electrical remodeling underlying AF susceptibility. Sex differences were only observed in controls with female pigs showing an increased intrinsic heart rate, a prolonged QRS interval and a prolonged sinus node recovery time. In sum, susceptibility for AF is significantly increased both in male and female pigs with ischemic heart failure. Differences between males and females are moderate, including more and longer AF episodes in male pigs and sinus node dysfunction in female pigs.

Sex differences in presentation of atrial fibrillation: Findings from 30-day ambulatory monitoring in real-world practice

Background

Women are less likely to receive oral anticoagulation or ablation for treatment of atrial fibrillation (AF). Identification of sex differences in arrhythmia characteristics and symptoms may lead to a better understanding of potential reasons for these differences.

Objectives

To determine sex differences in AF with respect to heart rate, duration, burden, and symptoms in patients undergoing mobile cardiac telemetry (MCT) monitoring.

Methods

All patients who registered for ≤30-day MCT using PocketECG (MediLynx) in the USA in 2017 were included (n = 27,512, 58 % women). PocketECG records and transmits a three-lead ambulatory electrocardiogram (ECG) with real-time beat-to-beat analysis. Sex-related differences were analyzed with Chi2 and Spearmans rho.

Results

Fewer women than men were diagnosed with AF lasting ≥30s (13.7 % versus [vs] 19.0 %, p < 0.001). AF burden was lower in women in all age groups <90 years (all p < 0.01). Women were older at the time of AF diagnosis (median 76 vs 73 years, p < 0.001), had faster heart rate during AF (mean: 104.7 ± 26.0 vs 96.7 ± 26.7 bpm, p < 0.001), and shorter AF duration (mean: 96.2 ± 176.0 vs 121.6 ± 189.9 min, p < 0.001). There was a non-significant trend toward more symptoms (such as dizziness, racing heart, fatigue, or palpitations) during AF in women compared to men (46.5 % vs 43.7 %, p = 0.062).

Conclusions

AF was less prevalent and occurred at lower burdens in women than men in each age strata. Despite faster heart rates in AF in women, there were no significant sex differences in reported symptoms during AF. Sex differences in therapy cannot be explained by differences in symptoms or rates in AF.

Condensed abstract

Real-world data on sex differences in AF using a 30-day MCT monitoring device remain scarce. We aim to determine the sex differences in AF with respect to prevalence, burden, heart rate, and symptom in patients undergoing ≤30-day MCT monitoring. Our data analysis suggests that fewer women than men had AF, women were older at diagnosis of AF, and women with AF had higher mean heart rate, shorter mean AF duration, and lower mean AF burden than men. Further studies are needed to examine reasons for sex differences, specifically in relation to AF therapy and its impact on clinical outcomes.

Atrial Mitral and Tricuspid Regurgitation: Sex Matters. A Call for Action to Unravel the Differences Between Women and Men

Atrial functional regurgitation is caused by atrioventricular annulus dilation, with normal leaflets and ventricular dimensions and function within the normal range. Its occurrence, in both mitral and tricuspid valves, implies a worse prognosis due to the hemodynamic derangement they produce, but also constitutes a marker of greater comorbidity and more advanced disease. Predisposing conditions for these heart valve dysfunctions are mainly atrial fibrillation and heart failure with preserved ejection fraction. However, other factors like female sex also may be involved and influence their incidence, especially for atrial tricuspid regurgitation. In the present review, we analyze sex differences in the reported prevalence of atrial mitral and tricuspid regurgitation, and suggest possible mechanisms involved. Finally, we underline potential therapeutic and preventive strategies to reduce the burden of these heart valve disorders and discuss research gaps.

Representation of Females in Atrial Fibrillation Clinical Practice Guidelines

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia in males and females worldwide, and its prevalence is increasing. Management of AF is guided by evidence-based clinical practice guidelines which provide recommendations based on available evidence. The extent of sex-specific data in the AF literature used to provide guideline recommendations has not been investigated. Therefore, using the 2020 Canadian Cardiovascular Society (CCS) Atrial Fibrillation Management Guidelines as example, the purpose of this study was to review female representation and the reporting of sex-disaggregated data in the studies referenced in AF guidelines.

METHODS

Randomized controlled trials (RCTs), prospective and retrospective cohorts, were screened to calculate the proportion of study participants who were female and to establish whether studies provided sex disaggregated analyses. The participant prevalence ratio (PPR), a quotient of the female participant rate and the prevalence of females in the AF population, was calculated for each study.

RESULTS

A total of 885 studies included in the CCS guidelines were considered. Of those, 467 met the inclusion criteria. Overall, females represented 39.1% of the population in all studies and RCTs had the lowest proportions of females (33.8%, PPR: 0.70). Of studies with sex-disaggregated analyses (n=140 (29.9%)), single centered RCTs, and retrospective cohorts had the lowest and highest rate of sex-specific analyses respectively (11.5% vs 32.5%).

CONCLUSION

The evidence used to derive guideline recommendations may be inadequate for sex-specific recommendations. Until enough data can support female specific guidelines, increased inclusion of females in AF studies, may aid in the precision of recommendations.

Revealing the Influences of Sex Hormones and Sex Differences in Atrial Fibrillation and Vascular Cognitive Impairment

The impacts of sex differences on the biology of various organ systems and the influences of sex hormones on modulating health and disease have become increasingly relevant in clinical and biomedical research. A growing body of evidence has recently suggested fundamental sex differences in cardiovascular and cognitive function, including anatomy, pathophysiology, incidence and age of disease onset, symptoms affecting disease diagnosis, disease severity, progression, and treatment responses and outcomes. Atrial fibrillation (AF) is currently recognized as the most prevalent sustained arrhythmia and might contribute to the pathogenesis and progression of vascular cognitive impairment (VCI), including a range of cognitive deficits, from mild cognitive impairment to dementia. In this review, we describe sex-based differences and sex hormone functions in the physiology of the brain and vasculature and the pathophysiology of disorders therein, with special emphasis on AF and VCI. Deciphering how sex hormones and their receptor signaling (estrogen and androgen receptors) potentially impact on sex differences could help to reveal disease links between AF and VCI and identify therapeutic targets that may lead to potentially novel therapeutic interventions early in the disease course of AF and VCI.

Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior

Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.

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

The Canadian Cardiovascular Society (CCS) atrial fibrillation (AF) guidelines program was developed to aid clinicians in the management of these complex patients, as well as to provide direction to policy makers and health care systems regarding related issues. The most recent comprehensive CCS AF guidelines update was published in 2010. Since then, periodic updates were published dealing with rapidly changing areas. However, since 2010 a large number of developments had accumulated in a wide range of areas, motivating the committee to complete a thorough guideline review. The 2020 iteration of the CCS AF guidelines represents a comprehensive renewal that integrates, updates, and replaces the past decade of guidelines, recommendations, and practical tips. It is intended to be used by practicing clinicians across all disciplines who care for patients with AF. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system was used to evaluate recommendation strength and the quality of evidence. Areas of focus include: AF classification and definitions, epidemiology, pathophysiology, clinical evaluation, screening and opportunistic AF detection, detection and management of modifiable risk factors, integrated approach to AF management, stroke prevention, arrhythmia management, sex differences, and AF in special populations. Extensive use is made of tables and figures to synthesize important material and present key concepts. This document should be an important aid for knowledge translation and a tool to help improve clinical management of this important and challenging arrhythmia.

Impact of Female Sex on Clinical Presentation and Ablation Outcomes in the CIRCA-DOSE Study

OBJECTIVES

This study sought to evaluate sex-specific differences in atrial fibrillation (AF) presentation and catheter ablation outcomes in the prospective, multicenter, randomized CIRCA-DOSE (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation: Double Short vs. Standard Exposure Duration) study.

BACKGROUND

Similar to other cardiovascular conditions, significant sex-specific differences have been observed in the epidemiology, pathophysiology, presentation, and natural history of AF. Unfortunately, there are major gaps in our understanding of the pathophysiological basis for the observed sex-specific differences and their implications on therapy and prognosis.

METHODS

This study examined sex-specific differences in AF presentation, symptom severity and health-related quality of life, symptomatic and asymptomatic arrhythmia recurrence, AF burden, and health care utilization.

RESULTS

Freedom from any atrial tachyarrhythmia and symptomatic atrial tachyarrhythmia were similar between male (hazard ratio: 1.18; 95% confidence interval: 0.85 to 1.64; p = 0.39) and female patients (hazard ratio: 1.00; 95% confidence interval: 0.62 to 1.59; p = 0.92). Post-ablation, the median AF burden (percentage time in AF) was 0.00% (interquartile range: 0.00% to 0.16%) in male patients and 0.00% (interquartile range: 0.00% to 0.17%) in female patients, with no difference observed between the sexes (p = 0.30). Periprocedural complications occurred twice as frequently in female patients (3.5% vs. 7.0%; p = 0.18). In comparison to male patients, female patients reported a significantly worse symptom score and quality of life at baseline and all follow-up intervals, but they derived similar magnitude of improvement post-ablation. There was no difference between male and female patients with respect to emergency department visits, hospitalization, cardioversion, or repeat ablation.

CONCLUSIONS

When compared with male patients, female patients have significantly worse symptom scores and quality of life at baseline. Despite this, female patients with symptomatic paroxysmal AF derive similar benefit in freedom from recurrent arrhythmia and similar improvements in quality of life following AF ablation. (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation: Double Short vs. Standard Exposure Duration [CIRCA-DOSE]; NCT01913522).

Improving translational research in sex-specific effects of comorbidities and risk factors in ischaemic heart disease and cardioprotection: position paper and recommendations of the ESC Working Group on Cellular Biology of the Heart

Ischaemic heart disease (IHD) is a complex disorder and a leading cause of death and morbidity in both men and women. Sex, however, affects several aspects of IHD, including pathophysiology, incidence, clinical presentation, diagnosis as well as treatment and outcome. Several diseases or risk factors frequently associated with IHD can modify cellular signalling cascades, thus affecting ischaemia/reperfusion injury as well as responses to cardioprotective interventions. Importantly, the prevalence and impact of risk factors and several comorbidities differ between males and females, and their effects on IHD development and prognosis might differ according to sex. The cellular and molecular mechanisms underlying these differences are still poorly understood, and their identification might have important translational implications in the prediction or prevention of risk of IHD in men and women. Despite this, most experimental studies on IHD are still undertaken in animal models in the absence of risk factors and comorbidities, and assessment of potential sex-specific differences are largely missing. This ESC WG Position Paper will discuss: (i) the importance of sex as a biological variable in cardiovascular research, (ii) major biological mechanisms underlying sex-related differences relevant to IHD risk factors and comorbidities, (iii) prospects and pitfalls of preclinical models to investigate these associations, and finally (iv) will provide recommendations to guide future research. Although gender differences also affect IHD risk in the clinical setting, they will not be discussed in detail here.

Predictor of enhanced mortality in patients with multimorbidity and atrial fibrillation in an acute hospital setting

BACKGROUND

Patients with atrial fibrillation (AF) admitted to hospital commonly have comorbidities. Few studies have attempted to determine factors prognostic of mortality in hospitalized AF patients with multimorbidity.

AIM

To identify factors associated with mortality in hospitalized AF patients.

DESIGN

Retrospective cohort study.

METHODS

Patients with multimorbidity (≥2 chronic diseases), with or without AF, discharged from Lugo hospital (Spain) between 1 January 2000 and 31 December 2015. Data were extracted from hospital medical records.

RESULTS

Of 74 220 patients (170 978 hospitalizations), 52 939 had multimorbidity (14 181 had AF; 38 758 no AF) and were included in our study. Patients with AF were older (mean ± standard deviation 78.6 ± 10.0 vs. 71.9 ± 14.2 years) and had a higher mortality rate (27.1 vs. 20.5%) than those without AF. Gender (female), age, stroke and congestive heart failure (CHF), but not AF, were independently associated with mortality. AF significantly increased the mortality risk in women [relative risk (RR) 1.091; 95% confidence interval (CI) 1.021-1.165; P = 0.010] and in those aged >80 years (RR 1.153; 95% CI, 1.1-1.2; P < 0.001). CHF independently increased the risk of mortality across all age groups (RR 1.496; 95% CI 1.422-1.574; P < 0.001).

CONCLUSIONS

Hospitalized patients with AF have a higher mortality rate than those without AF. The prognostic significance of AF changes with age and gender while CHF is associated with the greatest risk of death.

Aging Modulates the Substrate and Triggers Remodeling in Atrial Fibrillation

Aging plays a critical role in the genesis of atrial fibrillation (AF) and also increases the risks of cardiac dysfunction and stroke in AF patients. AF is caused by increased AF triggering from abnormalities of the thoracic vein and/or modulated substrate (atrial) with enhancement of AF maintenance. Clinical and laboratory evidence indicates that aging is significant in the creation of atrial electrical and structural remodeling that leads to increased susceptibility to AF occurrence. Aging is commonly associated with cardiovascular comorbidities, oxidative stress, calcium dysregulation, atrial myopathy with apoptosis, and fibrosis, which all contribute to the genesis of AF. This review updates the current understanding of the effects of aging on the pathophysiology of AF.

Atrial Fibrillation and Ventricular Arrhythmias: Sex Differences in Electrophysiology, Epidemiology, Clinical Presentation, and Clinical Outcomes

Sex-specific differences in the epidemiology, pathophysiology, clinical presentation, clinical treatment, and clinical outcomes of atrial fibrillation (AF), sustained ventricular arrhythmias, and sudden cardiac death are recognized. Sex hormones cause differences in cardiac electrophysiological parameters between men and women that may affect the risk for arrhythmias. The incidence and prevalence of AF is lower in women than in men. However, because women live longer and AF prevalence increases with age, the absolute number of women with AF exceeds that of men. Women with AF are more symptomatic, present with more atypical symptoms, and report worse quality of life in comparison with men. Female sex is an independent risk factor for death or stroke attributable to AF. Oral anticoagulation therapy for stroke prevention has similar efficacy for men and women, but older women treated with warfarin have a higher residual risk of stroke in comparison with men. Women with AF are less likely to receive rhythm control antiarrhythmic drug therapy, electric cardioversion, or catheter ablation in comparison with men. The incidence and prevalence of sustained ventricular arrhythmias and sudden cardiac death are lower in women than in men. Women receiving implantable cardioverter defibrillators for primary prevention of sudden cardiac death are less likely to experience sustained ventricular arrhythmias in comparison with men. In contrast, women receiving a cardiac resynchronization therapy implantable cardioverter defibrillator for the treatment of heart failure are more likely to benefit than men. Women are less likely to be referred for implantable cardioverter defibrillator therapy despite current guideline recommendations. Women are more likely to experience a significant complication related to implantable cardioverter defibrillator implantation in comparison with men. Whether sex differences in treatment decisions reflect patient preferences or treatment biases requires further study.

Challenging Achievement of Bidirectional Block After Linear Ablation Affects the Rhythm Outcome in Patients With Persistent Atrial Fibrillation

Background

It is not clear whether bidirectional block (BDB) of linear ablations reduces atrial fibrillation (AF) recurrence after radiofrequency catheter ablation. We hypothesized that BDB of linear ablation has prognostic significance after radiofrequency catheter ablation for persistent AF.

Methods and Results

Among 1793 consecutive patients in the Yonsei AF ablation cohort, this observational cohort study included 398 patients with persistent AF (75.6% male; age, 59.8±10.3 years) who underwent catheter ablation with a consistent ablation protocol of the Dallas lesion set: circumferential pulmonary vein isolation; cavotricuspid isthmus ablation (CTI); roof line (RL); posterior‐inferior line (PIL); and anterior line (AL). BDB rates of de novo ablation lines were 100% in circumferential pulmonary vein isolation, 100% in CTI, 84.7% in RL, 44.7% in PIL, and 63.6% in AL. During 29.0±18.4 months of follow‐up, 31.7% (126/398) of the patients showed clinical recurrence. Left atrial posterior wall (LAPW) isolation (BDBs of RL and PIL) was independently associated with lower clinical AF/atrial tachycardia recurrence (hazard ratio, 0.68; 95% CI, 0.47–0.98; P=0.041; log‐rank, P=0.017), whereas BDBs of RL or AL were not (log‐rank, P=0.178 for RL; P=0.764 for AL). Among 52 patients who underwent repeat procedures (23.0±16.1 months after de novo procedure), the BDB maintenance rates for CTI, RL, PIL, and AL were 94.2% (49 of 52), 63.5% (33 of 47), 62.1% (18 of 29), and 61.8% (21 of 34), respectively.

Conclusions

Although PIL crosses the esophageal contact area, LAPW isolation is important for better clinical outcome in catheter ablation with a linear ablation strategy for patients with persistent AF.

Advanced Left Atrial Remodeling and Appendage Contractile Dysfunction in Women Than in Men Among the Patients With Atrial Fibrillation: Potential Mechanism for Stroke

Background

The risk of stroke imposed by atrial fibrillation (AF) is significantly greater in women than men; however, the mechanism remains elusive. We hypothesized that left atrial (LA) remodeling and poor contractile function of LA appendage (LAA) would be more predominant in women than men among AF patients.

Methods and Results

A total of 579 AF patients (216 women vs age‐, AF type–, and incidences of heart failure, hypertension, diabetes mellitus, stroke or transient ischemic attack, and vascular disease–matched 363 men, 61.3±10.2 years old, 70.1% paroxysmal AF) who underwent AF catheter ablation were included. Sex differences in LA volume index (LAVI) and LAA emptying flow velocity (FV) were analyzed in risk factor 0, 1, and ≥2 groups, according to their CHA₂DS₂‐VASc scores beyond sex category. LAA‐FV was more significantly reduced in women with risk factor ≥2 than in men of the same risk group (P=0.022). Women showed greater LAVI than their male counterparts in the risk factor ≥2 group (P<0.001). The majority of female patients with a history of stroke had a large LAVI and low LAA‐FV (P<0.001); however, no such distribution was observed in men (P=0.596). LA volume index (odds ratio [OR], 1.038; 95% CI, 1.003–1.075, P=0.035) or LAA‐FV (OR, 0.976; 95% CI, 0.952–0.999; P=0.047) was significantly associated with a history of stroke in women.

Conclusions

More‐extensive LA remodeling and deterioration in LAA function were noted in women than in men with high calculated risk of stroke in AF.

Atrial fibrillation in women: epidemiology, pathophysiology, presentation, and prognosis

Atrial fibrillation (AF) is the most common sustained arrhythmia in women and men worldwide. During the past century, a range of risk factors has been associated with AF, severe complications from the arrhythmia have been identified, and its prevalence has been increasing steadily. Whereas evidence has accumulated regarding sex-specific differences in coronary heart disease and stroke, the differences between women and men with AF has received less attention. We review the current literature on sex-specific differences in the epidemiology of AF, including incidence, prevalence, risk factors, and genetics, and in the pathophysiology and the clinical presentation and prognosis of patients with this arrhythmia. We highlight current knowledge gaps and areas that warrant future research, which might advance understanding of variation in the risk factors and complications of AF, and ultimately aid more-tailored management of the arrhythmia.

Gender differences in electrophysiological characteristics of idiopathic ventricular tachycardia originating from right ventricular outflow tract

It has become increasingly apparent in recent years that there are important differences of many cardiovascular disorders including ventricular tachycardias in men and women. Nevertheless, so far just few studies have addressed possible gender differences in electrophysiological characteristics of idiopathic ventricular tachycardia from right ventricular outflow tract (RVOT-VT), other than epidemiological ones. This study explored possible gender differences in electrophysiological characteristics and catheter ablation outcome in RVOT-VT patients. Ninety-three patients (mean age 38.7+/-15.5 years, 30 males) with idiopathic RVOT-VT were enrolled and analyzed in our study. Male patients had longer QRS width (99.9+/-19.4 ms vs. 88.4+/-20.7 ms, p=0.02). Female patients had lower right ventricular mean voltage (3.0+/-0.7 mV vs. 3.7+/-0.9 mV, p=0.03), and more low voltage zone over the right ventricular outflow tract free wall (27.0 % vs. 6.7 %, p=0.02). Eighty-one patients passed catheter ablation (23 males). The acute success rate, repeated catheter ablation rate and VT recurrence rate were similar in both genders. The present study provides evidence of the gender differences in electrophysiological findings in patients with idiopathic RVOT-VT. Studies on gender-specific differences in arrhythmia could lead to a better understanding of its mechanism(s) and provide valuable information for the development of optimal treatment strategies.

Absence of gender-based differences in the atrial and pulmonary vein substrate: a detailed electroanatomic mapping study

BACKGROUND

Gender-based differences in the clinical nature of cardiac arrhythmias such as atrial fibrillation (AF) are well established.

OBJECTIVE

The purpose of this study was to identify any such gender-based differences in the underlying pulmonary vein and atrial substrate.

METHODS AND RESULTS

Thirty-eight patients with no history of AF undergoing catheter ablation for supraventricular tachycardia (SVT) and 55 with paroxysmal or persistent AF undergoing catheter ablation of AF underwent detailed electroanatomic mapping of the pulmonary veins and atria. Refractory periods in multiple locations, sinus node function, endocardial bipolar voltage, pulmonary vein and atrial conduction, and bipolar electrogram complexity were analyzed. There were no significant between-gender differences in age or other clinical variables known to impact on the atrial or pulmonary vein substrate. In neither the AF nor the non-AF cohorts were there any significant differences in atrial or pulmonary vein refractoriness, sinus node function, any measure of PV electrophysiology, or any measure of atrial electrophysiology.

CONCLUSION

No systematic between-gender differences were observed in the PV or atrial substrate either in those with or without a history of AF, with a similar prevalence of the cardiovascular comorbidities frequently associated with atrial remodeling and AF seen in both male and female groups.

Rivaroxaban modulates electrical and mechanical characteristics of left atrium

Background

Rivaroxaban reduces stroke in patients with atrial fibrillation (AF). Left atrium (LA) plays a critical role in the pathophysiology of AF. However, the electromechanical effects of rivaroxaban on LA are not clear.

Results

Conventional microelectrodes and a whole-cell patch-clamp were used to record the action potentials (APs) and ionic currents in rabbit LA preparations and isolated single LA cardiomyocytes before and after the administration of rivaroxaban. Rivaroxaban (10, 30, 100, and 300 nM) concentration-dependently reduced LA (n = 7) AP durations at 90% repolarization (APD₉₀) from 76 ± 2 to 79 ± 3, 67 ± 4 (P < 0.05, vs. control), 59 ± 5, (P < 0.01, vs. control), and 56 ± 4 ms (P < 0.005, vs. control), respectively. Rivaroxaban (10, 30, 100, and 300 nM) concentration-dependently increased the LA (n = 7) diastolic tension by 351 ± 69 (P < 0.05, vs. control), 563 ± 136 (P < 0.05, vs. control), 582 ± 119 (P < 0.05, vs. control), and 603 ± 108 mg (P < 0.005, vs. control), respectively, but did not change LA contractility. In the presence of L-NAME (100 μM) and indomethacin (10 μM), additional rivaroxaban (300 nM) treatment did not significantly further increase the LA (n = 7) diastolic tension, but shortened the APD₉₀ from 73 ± 2 to 60 ± 6 ms (P < 0.05, vs. control). Rivaroxaban (100 nM) increased the L-type calcium current and ultra-rapid delayed rectifier potassium current, but did not change the transient outward potassium current in isolated LA cardiomyocytes.

Conclusions

Rivaroxaban modulates LA electrical and mechanical characteristics with direct ionic current effects.

ATX-II-induced pulmonary vein arrhythmogenesis related to atrial fibrillation and long QT syndrome

BACKGROUND

Long QT syndrome (LQTS) is associated with a high incidence of atrial fibrillation (AF), but the underlying mechanisms are unclear. Pulmonary veins (PVs) play a critical role in AF genesis. Type 3 LQTS increases late sodium current (I(Na,L) ), which may increase PV arrhythmogenesis and AF. Therefore, this study examines PV arrhythmogenesis in anemonia sulcata toxin II (ATX-II)-induced type 3 LQTS and evaluates whether the I(Na,L) inhibitor ranolazine can suppress PV arrhythmogenesis.

MATERIALS AND METHODS

Conventional microelectrodes were used to record the action potentials (AP) and contractility in isolated rabbit PV specimens before and after ATX-II administration with or without ranolazine.

RESULTS

Anemonia sulcata toxin II (100 nM) increased the PV spontaneous rates from 2·0 ± 0·1 to 2·9 ± 0·2 Hz (n = 7), induced PV burst firing (100%) with the genesis of early afterdepolarization (EAD) (86%) and prolonged the AP duration. Ranolazine (0·1, 1 and 10 μM) dose dependently reduced the PV spontaneous rates from 2·5 ± 0·2 to 2·3 ± 0·2 Hz, 1·9 ± 0·2 and 1·5 ± 0·3 Hz (P < 0·05) and decreased the diastolic tension by 40 ± 19%, 87 ± 26% and 113 ± 28%. In the presence of ranolazine (10 μM), ATX-II (100 nM) further increased the AP duration. However, ATX-II neither increased the PV spontaneous rates (1·6 ± 0·1 vs. 1·7 ± 0·2 Hz, n = 7) nor induced PV burst firing or EAD. Moreover, ranolazine (10 μM) reduced ATX-II-induced PV acceleration and EAD.

CONCLUSIONS

The I(Na,L) enhancer ATX-II can increase PV arrhythmogenesis, which can be attenuated or blocked by ranolazine. This suggests that AF may be related to type 3 LQTS through increased I(Na,L) .