Effect of Female Sex on Cardiac Arrhythmias

Sex hormone trajectories and association to outcomes after out-of-hospital cardiac arrest

BACKGROUND

Outcomes and susceptibility to out-of-hospital cardiac arrest (OHCA) are known to differ by sex, yet little is known about changes in sex hormones after OHCA. We sought to determine the trajectory of sex hormones after OHCA and their association to survival and neurological outcome.

METHODS

Plasma samples were collected from those that survived to hospital admission at four time points (1, 6, 24, and 48 h) and estrone, estradiol, progesterone, and testosterone concentrations were quantified via liquid chromatography-mass spectrometry. Trends in hormones were plotted over time by sex and outcomes. The association between sex, hormone levels with survival and neurological outcome (cerebral performance category 1-2 indicating good outcome and 3-5 for poor outcome) were determined using generalized estimating equation models.

RESULTS

Of the 94 OHCA patients, 50 were males and 44 females, with a mean age of 61.3 (+15.7) years. Despite older age and lower BCPR in females compared to males, females had higher proportion of good neurological outcome compared to males. Over the 48 h, estrone increased, testosterone decreased, and estradiol and progesterone remained flat. Survivors had lower levels of estrone at all time points but only at early time points for estradiol, progesterone and testosterone. Lower estrone level predicted survival at discharge, even after adjusting for time, sex, age, and hormones independently (β = -3.38, 95% CI = -5.71, -0.85). Females had better neurological scores compared to males after adjusting for estrone (β = 1.27, 95% CI = 0.01, 2.53) and estradiol (β = 2.92, 95% CI = 1.13, 4.70).

CONCLUSIONS

Survivors and those with favorable neurological outcome had lower trend in estrone. The sex hormone estrone, present in both males and females, may be a predictor of survival. When adjusted for estrogens, female sex had better neurological recovery compared to males. The difference in neurological outcome by sex is not explained by estrogens. However, these finding open the door for exploration of other sex-specific pathways in resuscitation after OHCA.

Publication guidelines for human heart rate and heart rate variability studies in psychophysiology-Part 1: Physiological underpinnings and foundations of measurement

This Committee Report provides methodological, interpretive, and reporting guidance for researchers who use measures of heart rate (HR) and heart rate variability (HRV) in psychophysiological research. We provide brief summaries of best practices in measuring HR and HRV via electrocardiographic and photoplethysmographic signals in laboratory, field (ambulatory), and brain-imaging contexts to address research questions incorporating measures of HR and HRV. The Report emphasizes evidence for the strengths and weaknesses of different recording and derivation methods for measures of HR and HRV. Along with this guidance, the Report reviews what is known about the origin of the heartbeat and its neural control, including factors that produce and influence HRV metrics. The Report concludes with checklists to guide authors in study design and analysis considerations, as well as guidance on the reporting of key methodological details and characteristics of the samples under study. It is expected that rigorous and transparent recording and reporting of HR and HRV measures will strengthen inferences across the many applications of these metrics in psychophysiology. The prior Committee Reports on HR and HRV are several decades old. Since their appearance, technologies for human cardiac and vascular monitoring in laboratory and daily life (i.e., ambulatory) contexts have greatly expanded. This Committee Report was prepared for the Society for Psychophysiological Research to provide updated methodological and interpretive guidance, as well as to summarize best practices for reporting HR and HRV studies in humans.

Sex differences in clinical characteristics and prognosis of patients with cardiac sarcoidosis

OBJECTIVE

Owing to the paucity of data, this study aimed to investigate sex differences in clinical features and prognosis of patients with cardiac sarcoidosis (CS).

METHODS

This study was a secondary analysis of the ILLUstration of the Management and prognosIs of JapaNese PATiEnts with Cardiac Sarcoidosis registry-a retrospective multicentre registry that enrolled patients with CS between 2001 and 2017. The primary outcome was potentially fatal ventricular arrhythmia events (pFVAEs)-a composite of sudden cardiac death, sustained ventricular tachycardia lasting >30 s, ventricular fibrillation or the requirement for implantable cardioverter defibrillator therapy.

RESULTS

Of the 512 participants (mean age±SD 61.6±11.4 years), 329 (64.2%) were females. Both sexes had peak ages of 60-64 years at diagnosis. Male patients were younger and had a higher prevalence of coronary artery disease and lower left ventricular ejection fraction than female patients. During a median follow-up of 3 years (IQR 1.6-5.6), pFVAEs were observed in 99 patients, with males having a significantly higher risk than females (p=0.002). This association was retained even after adjustment for other risk factors for pFVAEs, including left ventricular ejection fraction (adjusted HR 1.80; 95% CI 1.08 to 3.01, p=0.025).

CONCLUSION

Approximately two-thirds of patients with CS were females, with a peak age of approximately 60 years at clinical diagnosis in both sexes; male patients were younger than female patients. Male patients had a significantly higher risk of pFVAEs than female patients.

TRIAL REGISTRATION NUMBER

UMIN000034974.

Three-Dimensional-Derived Echocardiographic Left Ventricular Structure and Function and Indices from the 12-Lead Electrocardiogram across the Menstrual Cycle in Healthy Physically Active Females: An Exploratory Study

Background: The impact of the menstrual phases on left ventricular (LV) structure and function using 3D echocardiography and resting electrocardiogram (ECG) in healthy, eumenorrheic, and physically active females has not been investigated. Methods: sixteen females (20 y ± 2) underwent 3D echocardiography and an ECG at three time points in the menstrual cycle phases (follicular, ovulation, luteal). LV end-diastolic volume (LVEDVi), LV ejection fraction (LVEF), LV mass allometrically indexed to height2.7 (LVMi), torsion, and global longitudinal, circumferential, and radial strain (GLS, GCS, and GRS) were evaluated. ECG data of the P and QRS waves were presented as well as axis deviation, chamber enlargement, and any rhythm abnormalities. Results: LVMi was significantly higher in the luteal phase (36.4 g/m2.7 ± 3.3) compared to the follicular (35.0 g/m2.7 ± 3.7) and ovulation (34.7 g/m2.7 ± 4.3) phases (p = 0.026). There were no differences in other indices of LV structure and function or ECG variables across all phases of the menstrual cycle or evidence of arrhythmia. Conclusions: In physically active females, there is a small but significantly higher LVMi associated with the luteal phase of the menstrual cycle with no concomitant change in LV function or ECG parameters. These findings are important to consider when conducting clinical or research serial assessments.

Acute exposure to low-dose bisphenol A delays cardiac repolarization in female canine heart - Implication for proarrhythmic toxicity in large animals

Bisphenol A (BPA) is a common environmental chemical with a range of potential adverse health effects. The impact of environmentally-relevant low dose of BPA on the electrical properties of the hearts of large animals (e.g., dog, human) is poorly defined. Perturbation of cardiac electrical properties is a key arrhythmogenic mechanism. In particular, delay of ventricular repolarization and prolongation of the QT interval of the electrocardiogram is a marker for the risk of malignant arrhythmias. We examined the acute effect of 10-9 M BPA on the electrical properties of female canine ventricular myocytes and tissues. BPA rapidly delayed action potential repolarization and prolonged action potential duration (APD). The dose response curve of BPA on APD was nonmonotonic. BPA rapidly inhibited the IKr K+ current and ICaL Ca2+ current. Computational modeling indicated that the effect of BPA on APD can be accounted for by its suppression of IKr. At the tissue level, BPA acutely prolonged the QT interval in 4 left ventricular wedges. ERβ signaling contributed to the acute effects of BPA on ventricular repolarization. Our results demonstrate that BPA has QT prolongation liability in female canine hearts. These findings have implication for the potential proarrhythmic cardiac toxicity of BPA in large animals.

Treatment-Related Coronary Disorders of Fluoropyrimidine Administration: A Systematic Review and Meta-Analysis

Background: Coronary disorders are recognized as the most common manifestation of fluoropyrimidine-related cardiotoxicity in clinical practice. However, there are limited and conflicting data on the incidence and profiles of fluoropyrimidine-related coronary disorders. In this meta-analysis, we aimed to systematically assess the incidence of all-grade and grade 3 or higher fluoropyrimidine-related coronary disorders, and further explore the factors that influence its occurrence.

Methods: Studies reporting the fluoropyrimidine-related coronary disorders were retrieved from a systematic search of English literature in the PubMed, Web of Science, Medline, and Cochrane database from 1 Jan 2001, to 1 Jan 2022. The NIH assessment tool was used to evaluate the quality of each study. The data of basic study characteristics, treatment details, and results of coronary toxicities were extracted. According to the results of the heterogeneity test (I² and p-value statistic), a random-effect model or fixed-effect model was selected for the pooled analysis of the incidence of adverse coronary events. Subgroup analysis was conducted to further explore the risks influencing the occurrence of fluoropyrimidine-related coronary disorders. The stability and publication bias of our results were evaluated by sensitivity analysis and Egger test, respectively.

Results: A total of 63 studies were finally included in our pooled analysis, involving 25,577 patients. The pooled cumulative incidence of all-grade and grade 3 or higher coronary disorders was 2.75% (95% CI 1.89%–3.76%) and 1.00% (95% CI 0.62%–1.47%), respectively. The coronary disorders were most reported as myocardial ischemia (1.28%, 95% CI 0.42%–2.49%) and angina/chest pain (1.1%, 95% CI 0.54%–1.81%). Subgroup analysis revealed that studies in the female-only population seemed to have a lower incidence of fluoropyrimidine-related coronary disorders. The occurrence of adverse coronary events varied among different tumor types. Patients with esophageal cancer have the highest coronary toxicity (6.32%), while those with breast cancer have a relatively lower incidence (0.5%). Coronary disorders induced by 5-FU monotherapy are more frequent than that induced by capecitabine (3.31% vs. 1.21%, p < 0.01). Fluoropyrimidine combination therapy, whether combined with other chemotherapy drugs, targeted therapy drugs, or radiotherapy, significantly increased the incidence of coronary complications (p < 0.01).

Conclusion: This meta-analysis has defined the incidence of fluoropyrimidine-related coronary disorders and depicted its epidemiological profiles for the first time, which may provide a reference for clinical practice in cancer management.

Investigation of the Effects of Cardiovascular Therapeutic Ultrasound Applied in Female and Male Rats' Hearts of Different Ages

This study investigates the role of age and sex on the cardiovascular effects of 3.5-MHz pulsed ultrasound (US) in a rat model. Ultrasonic bursts of 2.0-MPa peak rarefactional pressure amplitude (equivalent to an in vitro spatial-peak temporal-peak intensity of ~270 W/cm2 and a mechanical index of 1.1) were delivered in five consecutive 10-s intervals, one interval for each pulse repetition frequency (PRF) (6, 5, 4, 5, and 6 Hz; always the same order) for a total exposure duration of 50 consecutive seconds. Sixty F344 rats were split into 12 groups in a 3×2×2 factorial design (three ages, male versus female, and US application versus control). This study is the first study on US-induced cardiac effects that contains data across three age groups of rats (premenopause, fertile, and postmenopause) to mimic the fertile and nonfertile human window. US was applied transthoracically, while heart rate, stroke volume, ejection fraction, temperature, and other physiologic parameters were recorded at baseline and after exposure. Significant decreases in cardiac output compared to respective control groups were observed in multiple experimental groups, spanning both females and males. A negative chronotropic effect was observed in young male (~7%) and female (~16%) rats, in five-month-old male (~9%) and female (~15%) rats, and in old rats where the effect was not statistically significant. Younger groups and, to a lesser extent, lower weight groups generally had more significant effects. The pathophysiology of US-induced cardiovascular effects appears to be multifactorial and not strictly related to hormones, menopause, weight, sex, or age, individually.

Hydrogen Sulfide Ameliorates Angiotensin II-Induced Atrial Fibrosis Progression to Atrial Fibrillation Through Inhibition of the Warburg Effect and Endoplasmic Reticulum Stress

Atrial fibrosis is the basis for the occurrence and development of atrial fibrillation (AF) and is closely related to the Warburg effect, endoplasmic reticulum stress (ERS) and mitochondrion dysfunctions-induced cardiomyocyte apoptosis. Hydrogen sulfide (H₂S) is a gaseous signalling molecule with cardioprotective, anti-myocardial fibrosis and improved energy metabolism effects. Nevertheless, the specific mechanism by which H₂S improves the progression of atrial fibrosis to AF remains unclear. A case-control study of patients with and without AF was designed to assess changes in H₂S, the Warburg effect, and ERS in AF. The results showed that AF can significantly reduce cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate thiotransferase (3-MST) expression and the H₂S level, induce cystathionine-β-synthase (CBS) expression; increase the Warburg effect, ERS and atrial fibrosis; and promote left atrial dysfunction. In addition, AngII-treated SD rats had an increased Warburg effect and ERS levels and enhanced atrial fibrosis progression to AF compared to wild-type SD rats, and these conditions were reversed by sodium hydrosulfide (NaHS), dichloroacetic acid (DCA) or 4-phenylbutyric acid (4-PBA) supplementation. Finally, low CSE levels in AngII-induced HL-1 cells were concentration- and time-dependent and associated with mitochondrial dysfunction, apoptosis, the Warburg effect and ERS, and these effects were reversed by NaHS, DCA or 4-PBA supplementation. Our research indicates that H₂S can regulate the AngII-induced Warburg effect and ERS and might be a potential therapeutic drug to inhibit atrial fibrosis progression to AF.

Short-term exposure to ambient air pollution and atrial fibrillation hospitalization: A time-series study in Yancheng, China

Atrial fibrillation (AF) is an important cardiovascular disease that causes a great burden of disease. However, there is limited evidence of a link between air pollution exposure and AF. This study aimed to explore the short-term association between air pollution and AF. We obtained daily hospitalization of AF in two major hospitals of Yancheng, China from May, 2015 to May, 2020. Generalized additive models with quasi-Poisson regression were used to assess the associations between six criteria air pollutants and AF hospitalization. We explored the lag patterns, and visualized the concentration-response relationships. The robustness of the association was tested by two-pollutant model, and we explored potential effect modification by age, sex and season. A total of 15,171 inpatients from two hospitals were collected in this study with an average daily count of eight patients. We observed consistent and significant associations between six air pollutants and AF on lag 0-4 days. A 10 ug/m3 increase in PM2.5 was associated with 2.81% (95%CI: 1.44%, 4.20%) changes in AF, and the effect estimate was 1.67% (95%CI: 0.77%, 2.59%) for PM10, 4.90% (95%CI: 1.69%, 8.22%) for NO2, 6.81% (95%CI: 0.46%, 13.57%) for SO2, 1.82% (95%CI: 0.60%, 3.06%) for O3; a 0.1 mg/m3 increase in CO was associated with 2.55% (95%CI: 0.91%, 4.21%) increments in AF. Associations of PM2.5 and PM10 were robust after adjusting for SO2, NO2, CO, and O3, but not vice versa. Female patients and those aged less 70 years had larger risk of AF associated with air pollution exposure. The concentration-response curves of the six pollutants were almost linear and increasing with no obvious thresholds. This time-series study in Yancheng demonstrated increased risk of AF and a delayed effect over lag 0-4 days. Our findings suggested need of prevention and protection against these environmental risk factors for AF in health departments.

The Effects of Different Hormones on Supraventricular and Ventricular Premature Contractions in Healthy Premenopausal Women

Background and Objectives: The effects of gender differences on cardiac parameters have been well-established. In this study, we aimed to evaluate the possible associations of plasma levels of different sex hormones with premature atrial or ventricular contractions in premenopausal women. Materials and Methods: We conducted a prospective study which included women in late reproductive age who presented with palpitations during an eight-month period. A 12-lead electrocardiography, a transthoracic echocardiogram, blood samples, and 24-hour rhythm Holter were conducted on the third day of the menstrual cycle. Results Overall, 93 healthy premenopausal women with a median age of 42 years were enrolled. QTc interval was within normal limits in all patients. The 24 h range of premature atrial contractions (PACs) and premature ventricular contractions (PVCs) was 0–6450 and was 0–21,230, respectively. The median number of PVCs was 540 and the median number of PACs was 212, respectively. In total, 51 patients (54.8%) had a frequency of PVCs > 500/24 h and 37 patients (39.8%) had a frequency of PACs > 500/24 h, respectively. No statistically significant association was shown between any hormone and the frequency of PACs. Regarding PVCs, patients with a PVCs frequency > 500/24 h had higher estradiol levels compared to patients with PVCs less than 500/24 h (median 60 pg/mL versus 42 pg/mL, p = 0.02, OR: 1.01). No association was found between PVCs and other hormones. Conclusions: In premenopausal healthy women, higher estradiol levels are independently associated with increased PVCs. This suggests that estradiol in late reproductive stages may exert proarrhythmic effects.

Sex-specific differences in outcome and risk stratification of ventricular arrhythmias in implantable cardioverter defibrillator patients

AIMS

Risk stratification models of sudden cardiac death (SCD) are based on the assumption that risk factors of SCD affect risk to a similar extent in both sexes. The aim of the study is to evaluate differences in clinical outcomes between sexes and evaluate whether risk factors associated with appropriate device therapy (ADT) differ between men and women.

METHODS AND RESULTS

We performed a cohort study of implantable cardioverter defibrillator (ICD) patients referred for primary or secondary prevention of SCD between 2009 and 2018. Multivariable Cox regression models for prediction of ADT were constructed for men and women separately. Of 2300 included patients, 571 (25%) were women. Median follow-up was 4.6 (inter-quartile range: 4.4-4.9) years. Time to ADT was shorter for men compared with women [hazard ratio (HR) 1.71, P < 0.001], as was time to mortality (HR 1.37, P = 0.003). In women, only secondary prevention ICD therapy (HR 1.82, P < 0.01) was associated with ADT, whereas higher age (HR 1.20, P < 0.001), absence of left bundle branch block (HR 0.72, P = 0.01), and secondary prevention therapy (HR 1.80, P < 0.001) were independently associated with ADT in men. None of the observed parameters showed a distinctive sex-specific pattern in ADT.

CONCLUSIONS

Male ICD patients were at higher risk of ADT and death compared with female ICD patients, irrespective of an ischaemic or non-ischaemic underlying cardiomyopathy. Our study highlights the importance to stratify outcomes of ICD trials by sex, as study results differ between men and women. However, none of the available clinical parameters showed a clear sex-specific relation to ventricular arrhythmias. As a consequence, sex-specific risk stratification models of SCD using commonly available clinical parameters could not be derived.

Gender associated disparities in atrioventricular nodal reentrant tachycardia: A review article

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common sustained supraventricular arrhythmias. An understanding of gender-related differences in AVNRT epidemiology, diagnosis, treatment, outcome, and complications can help guide a more effective diagnosis and treatment of the condition. The study aimed to perform a review of the available literature regarding all aspects of gender-related differences of AVNRT. We focused on all aspects of gender-related differences regarding AVNRT between men and women. A literature search was performed using Google Scholar, PubMed, Springer, Ovid, and Science Direct. Many investigations have demonstrated that the prevalence of AVNRT exhibited a twofold women-to-men predominance. The potential mechanism behind this difference due to sex hormones and autonomic tone. Despite being more common in women, there is a delay in offering and performing the first-line therapy (catheter ablation) compared to men. There were no significant gender-related discrepancies in patients who underwent ablation therapy for AVNRT, regarding the acute success rate of the procedure, long-term success rate, and recurrence of AVNRT. AVNRT is more common in women due to physiological factors such as sex hormones and autonomic tone. Catheter ablation is equally safe and efficacious in men and women; however, the time between the onset of symptoms and ablation is significantly prolonged in women. It is important for the medical community to be aware of this discrepancy and to strive to eliminate such disparities that are not related to patients' choices.

Influence of sex on intracellular calcium homeostasis in patients with atrial fibrillation

Aims

Atrial fibrillation (AF) has been associated with intracellular calcium disturbances in human atrial myocytes, but little is known about the potential influence of sex and we here aimed to address this issue.

Methods and results

Alterations in calcium regulatory mechanisms were assessed in human atrial myocytes from patients without AF or with long-standing persistent or permanent AF. Patch-clamp measurements revealed that L-type calcium current (I_Ca) density was significantly smaller in males with than without AF (−1.15 ± 0.37 vs. −2.06 ± 0.29 pA/pF) but not in females with AF (−1.88 ± 0.40 vs. −2.21 ± 0.0.30 pA/pF). In contrast, transient inward currents (I_Ti) were more frequent in females with than without AF (1.92 ± 0.36 vs. 1.10 ± 0.19 events/min) but not in males with AF. Moreover, confocal calcium imaging showed that females with AF had more calcium spark sites than those without AF (9.8 ± 1.8 vs. 2.2 ± 1.9 sites/µm²) and sparks were wider (3.0 ± 0.3 vs. 2.2 ± 0.3 µm) and lasted longer (79 ± 6 vs. 55 ± 8 ms), favouring their fusion into calcium waves that triggers I_TIs and afterdepolarizations. This was linked to higher ryanodine receptor phosphorylation at s2808 in women with AF, and inhibition of adenosine A_2A or beta-adrenergic receptors that modulate s2808 phosphorylation was able to reduce the higher incidence of I_TI in women with AF.

Conclusion

Perturbations of the calcium homoeostasis in AF is sex-dependent, concurring with increased spontaneous SR calcium release-induced electrical activity in women but not in men, and with diminished I_Ca density in men only.

Decreasing myocardial estrogen receptors and antioxidant activity may be responsible for increasing ischemia- and reperfusion-induced ventricular arrhythmia in older female rats

AIMS

This study aimed to investigate the relationship between ischemia- and reperfusion-induced arrhythmia and blood serum estrogen levels, myocardial estrogen receptor levels, antioxidant enzyme activities, and the effects of the estrogen receptor blocker, fulvestrant (ICI 182 780).

MAIN METHODS

A total of 102 female Sprague-Dawley rats of different ages (2-3, 6-7, 14-15, and 20-21 months) were used in this study. Myocardial ischemia was produced by ligation of the descending branch of the left anterior descending coronary artery, and reperfusion was produced by releasing this artery. An electrocardiogram (ECG) and blood pressure were recorded for 6 min of ischemia and 6 min of reperfusion. The levels of superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT), estrogen receptor α (ERα), and estrogen receptor β (ERβ) in myocardial tissue and 17 beta-estradiol (E2) in blood serum were measured via enzyme-linked immunosorbent assay (ELISA). The results were compared using a Mann-Whitney U test, one-way analysis of variance (ANOVA), and a student's t-test.

KEY FINDINGS

It is not the changes in serum estrogen levels but the decreasing myocardial estrogen receptors and antioxidant activities that could be responsible for the occurrence of more severe arrhythmia in response to reperfusion in older female rats.

SIGNIFICANCE

The death rate due to a heart attack in younger men is higher than in women. However, it equalizes after the menopausal stage in women. In this study, the reason for the increasing sudden post-menopausal death rate in women was investigated experimentally.

Problematic Alcohol Use and Mortality Risk in Arrhythmia: Nationwide Study of 114,958 Hospitalizations

Objectives To assess the risk of in-hospital mortality due to alcohol use disorder (AUD) and other cardiovascular risk factors in arrhythmia inpatients. Methods We included 114,958 patients (age, 15-54 years) by conducting a cross-sectional cohort study using the Nationwide Inpatient Sample (NIS, 2010-2014). These patients were primarily managed for arrhythmia and further grouped by comorbid AUD. A logistic regression model was used to measure the odds ratio (OR) of association of AUD and in-hospital mortality after adjusting for demographic confounders and cardiovascular risk factors. Results Mortality risk statistically increases with age as elders (45-54 years) had two times higher risk (95% confidence interval [CI] 1.49-3.09), whereas men had a lower risk (OR 0.8, 95% CI 0.74-0.96) of inpatient death. Comorbid atherosclerosis (OR 4.5, 95% CI 3.38-5.92) and diabetes (OR 1.4, 95% CI 1.18-1.67) increased mortality risk in arrhythmia inpatients. AUD significantly increased the risk of mortality in arrhythmia inpatients (OR 1.7, 95% CI 1.43-2.07). Conclusions AUD is an independent risk factor for mortality in arrhythmia inpatients, and it is elevated by 72% in such patients. Strategies to reduce alcohol consumption and abstinence should be focused to improve the health-related quality of life of at-risk patients.

Association of Total Reproductive Years With Incident Atrial Fibrillation, and Subsequent Ischemic Stroke in Women With Natural Menopause

Background:

The association of lifetime exposure to endogenous sex hormone with incident atrial fibrillation (AF) and subsequent ischemic stroke has never been studied.

Methods:

This study involved 4 638 299 natural postmenopausal waomen aged ≥40 years without prior history of AF and with national breast cancer check-up between January 1, 2009 and December 31, 2014. The primary end point was incident AF, and the secondary end point was subsequent ischemic stroke once AF has developed. Cox proportional hazard regression analysis was used to estimate the risk of end points.

Results:

During the mean follow-up of 6.3 years, shorter total reproductive years (<30 years) were associated with 7% increased risk of AF after adjusting for confounding variables (adjusted hazard ratio [aHR], 1.07 [95% CI, 1.05–1.09]). Risk of AF declined progressively with every 5-yearly increment in total reproductive years ( P -for-trend <0.001). However, the prolonged (≥2 years) use of hormone replacement therapy after menopause was paradoxically associated with a 3% increase in AF risk (aHR, 1.03 [95% CI, 1.01–1.05]). For the secondary end point analysis, the risk of ischemic stroke after AF development significantly decreased with each 5-yearly increment in total reproductive years (with <30 years as reference; aHR, 0.93 [95% CI, 0.88–0.99] for 30–34 years; aHR, 0.84 [95% CI, 0.79–0.89] for 35–39 years; and aHR, 0.88 [95% CI, 0.80–0.97] for ≥40 years, P -for-trend <0.001).

Conclusions:

In women with natural menopause, shorter lifetime exposure to endogenous sex hormone, that is, shorter total reproductive years, was significantly associated with a higher risk of AF and subsequent ischemic stroke. Paradoxically, prolonged exogenous hormone replacement therapy increased the risk of incident AF.

Supraventricular tachycardia and the menstrual cycle

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the influence of the menstrual cycle on the occurrence of arrhythmia is still understudied.

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Episodes of arrhythmia might occur more frequently in the premenstrual phase.

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Taking the menstrual cycle into account when scheduling diagnostic tests might lead to more accurate diagnoses.

The Influence of Sex on Cardiac Physiology and Cardiovascular Diseases

Cardiovascular disease (CVD) is the leading cause of death world-wide. Most of treatment strategies were based on studies conducted on male patients. Studies have shown that significant differences exist between the two sexes in the development of CVD. There are certain differences between men and women in the structure and physiological functions of the heart such as left ventricular mass index, resting heart rate, and contractile function. Accordingly, the pathological features of the heart such as the extend of hypertrophy, fibrosis, and remodeling are also different. In addition, different genders also affect clinical symptoms, responses to treatment and prognosis in the development of CVD. Therefore, it is important to take these differences into consideration when design treatment options for men and women.

Comparing the incidence of ventricular arrhythmias during epicardial ablation in swine versus canine models

BACKGROUND

Choosing the appropriate animal model for development of novel technologies requires an understanding of anatomy and physiology of these different models. There are little data about the characteristics of different animal models for the study of technologies used for epicardial ablation. We aimed to compare the incidence of ventricular arrhythmias during epicardial radiofrequency ablation between swine and canine models using novel epicardial ablation catheters.

METHODS

We conducted a retrospective study using data obtained from epicardial ablation experiments performed on swine (Sus Scrofa) and canine (Canis familiaris) models. We compared the incidence of ventricular arrhythmias during ablation between swine and canine using multivariate regression analysis. Six swine and six canine animals underwent successful epicardial radiofrequency ablation. A total of 103 ablation applications were recorded.

RESULTS

Ventricular arrhythmias requiring cardioversion occurred in 13.11% of radiofrequency ablation applications in swine and 9.75% in canine (relative risk: 117.6%, 95% confidence interval [CI]: 83.97-164.69, animal-based odds ratio [OR]: .55, 95% CI: .23-61.33; P = .184). When adjusting for application position, duration of ablation and power, the odds of developing potentially lethal ventricular arrhythmia in swine increased significantly compared to canine (OR: 3.60, 95% CI: 1.35-9.55; P = .010).

CONCLUSIONS

The swine myocardium is more susceptible to developing ventricular arrhythmias compared to canine model during epicardial ablation. This issue should be carefully considered in future studies.

Role of miRNA in the Regulatory Mechanisms of Estrogens in Cardiovascular Ageing

Cardiovascular diseases are a worldwide health problem and are the leading cause of mortality in developed countries. Together with experimental data, the lower incidence of cardiovascular diseases in women than in men of reproductive age points to the influence of sex hormones at the cardiovascular level and suggests that estrogens play a protective role against cardiovascular disease and that this role is also modified by ageing. Estrogens affect cardiovascular function via their specific estrogen receptors to trigger gene expression changes at the transcriptional level. In addition, emerging studies have proposed a role for microRNAs in the vascular effects mediated by estrogens. miRNAs regulate gene expression by repressing translational processes and have been estimated to be involved in the regulation of approximately 30% of all protein-coding genes in mammals. In this review, we highlight the current knowledge of the role of estrogen-sensitive miRNAs, and their influence in regulating vascular ageing.

Comparison of non-invasive assessment of arrhythmias, conduction disturbances and cardiac autonomic tone in systemic sclerosis and systemic lupus erythematosus

Systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) are connective tissue diseases presenting cardiac complications including different arrhythmias, then direct electrocardiographic comparison may be useful in everyday clinical decision making. We examined 86 adult SSc patients, 76 with SLE and 45 healthy controls. Among other examinations all subjects underwent 24-h Holter monitoring with time-domain heart rate variability and heart rate turbulence evaluation. Patients with various co-existing conditions which might markedly influence arrhythmias and autonomic modulation were excluded from further analysis (SSc n = 12, SLE n = 6). Finally, 76 SSc and 70 SLE subjects were eligible for this study, mean age 51.9 ± 13.1 and 46.5 ± 12.7 years (p = 0.11), with median disease duration 6.0 and 8.5 years (p = 0.15), respectively. As compared to SLE, patients with SSc were characterised by more frequent incidence of various supraventricular and ventricular arrhythmias. As compared to SSc, patients with SLE presented prolonged corrected QT intervals and also significant correlations between corrected QT length and heart rate variability indices. Both SSc and SLE subjects presented impaired sympathetic cardiac autonomic modulation, while indices associated with parasympathetic activity in SLE were not diminished. Disease duration was not associated with arrhythmias' occurrence (except for ventricular tachycardia in SSc, p = 0.02) and also with autonomic function in both groups of patients. Patients with SSc and SLE differ in terms of arrhythmias, conduction disturbances and cardiac autonomic tone. Regular Holter monitoring should be considered as a part of routine evaluation in connective tissue diseases patients, especially in systemic sclerosis.

The effects of gender on electrical therapies for the heart: physiology, epidemiology, and access to therapies

The difference between men and women is clear even just by looking at an electrocardiogram: females present higher resting heart rate, a shorter QRS complex length and greater corrected QT interval. The development of these differences from pubertal age onward suggests that sexual hormones play a key role, although their effect is far from being completely understood. Different incidences between sexes have been reported for many arrhythmias, both ventricular and supraventricular, and also for sudden cardiac death. Moreover, arrhythmias are an important issue during pregnancy, both for diagnosis and treatment. Interestingly, cardiovascular structural and electrophysiological remodelling promoted by exercise training enhances this 'gender effect'. Despite all these relevant issues, we lack gender specific recommendations in the current guidelines for electrical therapies for heart rhythm disorders and heart failure. Even more, we continue to see that fewer women are included in clinical trials and are less referred than men for these treatments.

miRNA as a New Regulatory Mechanism of Estrogen Vascular Action

The beneficial effects of estrogen on the cardiovascular system have been reported extensively. In fact, the incidence of cardiovascular diseases in women is lower than in age-matched men during their fertile stage of life, a benefit that disappears after menopause. These sex-related differences point to sexual hormones, mainly estrogen, as possible cardiovascular protective factors. The regulation of vascular function by estrogen is mainly related to the maintenance of normal endothelial function and is mediated by both direct and indirect gene transcription through the activity of specific estrogen receptors. Some of these mechanisms are known, but many remain to be elucidated. In recent years, microRNAs have been established as non-coding RNAs that regulate the expression of a high percentage of protein-coding genes in mammals and are related to the correct function of human physiology. Moreover, within the cardiovascular system, miRNAs have been related to physiological and pathological conditions. In this review, we address what is known about the role of estrogen-regulated miRNAs and their emerging involvement in vascular biology.

Atrial fibrillation in pregnancy: a growing challenge

BACKGROUND

Atrial fibrillation (AF) constitutes a relatively infrequent pregnancy complication, which may be a therapeutic Gordian knot. Indeed, sparse data exist regarding the prevalence, prognosis, and management of AF during pregnancy. In general, AF occurs as a benign, self-limited arrhythmia, but occasionally may have severe hemodynamic consequences in pregnant patients suffering from heart failure, congenital heart disease, or other comorbidities. Extra-cardiac causes of AF should always be meticulously excluded.

REVIEW

Treatment decisions are difficult, since medications may cross the placental barrier and potentially affect fetal growth and organogenesis, or even result in fetal bradyarrhythmias. Treatment goals are not differentiated in comparison to those regarding AF occurring in the general population. Still, while maternal treatment is prioritized, issues regarding fetal health must deliberately be considered. Consequently, hemodynamic instability is to be promptly treated with synchronized electrical cardioversion. In contrast, in stable patients, pharmacologic cardioversion, under appropriate antithrombotic regimen, should be attempted. Selection of appropriate antithrombotic therapy, including novel oral anticoagulants, imposes further difficulties on therapeutic decision-making. Further clinical trials are warranted in order to assess the pathophysiology and prognosis of AF in pregnancy and ameliorate the evidence-based therapeutic strategy in this specific group of the population.

Systematic screening for the detection of atrial fibrillation

BACKGROUND

Atrial fibrillation (AF), the most common arrhythmia in clinical practice, is a leading cause of morbidity and mortality. Screening for AF in asymptomatic patients has been proposed as a way of reducing the burden of the disease by detecting people who would benefit from prophylactic anticoagulation therapy before the onset of symptoms. However, for screening to be an effective intervention, it must improve the detection of AF and provide benefit for those detected earlier as a result of screening.

OBJECTIVES

This review aims to answer the following questions.Does systematic screening increase the detection of AF compared with routine practice? Which combination of screening population, strategy and test is most effective for detecting AF compared with routine practice? What safety issues and adverse events may be associated with individual screening programmes? How acceptable is the intervention to the target population? What costs are associated with systematic screening for AF?

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and EMBASE (Ovid) up to 11 November 2015. We searched other relevant research databases, trials registries and websites up to December 2015. We also searched reference lists of identified studies for potentially relevant studies, and we contacted corresponding authors for information about additional published or unpublished studies that may be relevant. We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials comparing screening for AF with routine practice in people 40 years of age and older were eligible. Two review authors (PM and CT) independently selected trials for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors (PM and CT) independently assessed risk of bias and extracted data. We used odds ratios (ORs) and 95% confidence intervals (CIs) to present results for the primary outcome, which is a dichotomous variable. As we identified only one study for inclusion, we performed no meta-analysis. We used the GRADE (Grades of Recommendation, Assessment, Development and Evaluation Working Group) method to assess the quality of the evidence and GRADEPro to create a 'Summary of findings' table.

MAIN RESULTS

One cluster-randomised controlled trial met the inclusion criteria for this review. This study compared systematic screening (by invitation to have an electrocardiogram (ECG)) and opportunistic screening (pulse palpation during a general practitioner (GP) consultation for any reason, followed by an ECG if pulse was irregular) versus routine practice (normal case finding on the basis of clinical presentation) in people 65 years of age or older.Results show that both systematic screening and opportunistic screening of people over 65 years of age are more effective than routine practice (OR 1.57, 95% CI 1.08 to 2.26; and OR 1.58, 95% CI 1.10 to 2.29, respectively; both moderate-quality evidence). We found no difference in the effectiveness of systematic screening and opportunistic screening (OR 0.99, 95% CI 0.72 to 1.37; low-quality evidence). A subgroup analysis found that systematic screening and opportunistic screening were more effective in men (OR 2.68, 95% CI 1.51 to 4.76; and OR 2.33, 95% CI 1.29 to 4.19, respectively) than in women (OR 0.98, 95% CI 0.59 to 1.62; and OR 1.2, 95% CI 0.74 to 1.93, respectively). No adverse events associated with screening were reported.The incremental cost per additional case detected by opportunistic screening was GBP 337, compared with GBP 1514 for systematic screening. All cost estimates were based on data from the single included trial, which was conducted in the UK between 2001 and 2003.

AUTHORS' CONCLUSIONS

Evidence suggests that systematic screening and opportunistic screening for AF increase the rate of detection of new cases compared with routine practice. Although these approaches have comparable effects on the overall AF diagnosis rate, the cost of systematic screening is significantly greater than the cost of opportunistic screening from the perspective of the health service provider. Few studies have investigated effects of screening in other health systems and in younger age groups; therefore, caution needs to be exercised in relation to transferability of these results beyond the setting and population in which the included study was conducted.Additional research is needed to examine the effectiveness of alternative screening strategies and to investigate the effects of the intervention on risk of stroke for screened versus non-screened populations.

Incidence, Characteristics, Risk Factors, and Outcomes of Takotsubo Cardiomyopathy With and Without Ventricular Arrhythmia

Takotsubo cardiomyopathy (TC) is a medical entity mimicking an acute coronary syndrome (ACS). Ventricular arrhythmia (VA) in TC has been reported in small studies, leading to uncertain knowledge of its incidence. We sought to describe the characteristics, incidence, predictive factors, and outcomes of VA in patients presenting with TC. Over a 12-year period, we reviewed all patients (n = 5,484) referred to our coronary care unit for a suspicion of ACS. TC was diagnosed in 90 patients according to the Mayo Clinic criteria. Incidence of VA among TC was 10%. In multivariate analysis, the factors significantly associated with an increased risk of VA were syncope (p = 0.007), age <55 years (p = 0.008), atypical TC (p = 0.04), a troponin I peak >7 μg/L (p = 0.04), and dobutamine use during hospitalization (p = 0.04). During follow-up, there was no significant difference in mortality rate between patients with or without VA. In conclusion, VA occurred in 10% of patients at the acute phase of TC and independent predictive factors of VA were syncope, atypical pattern of TC, high troponin peak, dobutamine use, and a relatively young age in a female and menopausal population. During the acute phase, identification of high-risk patients with VA allows better management, with electrocardiographic monitoring and therapeutic intervention in the coronary care unit.

Correlation of accessory pathway location with gender and their manifest or concealed presentation

BACKGROUND

Atrioventricular reentrant tachycardias account for approximately one third of cases referred for electrophysiological study (EPS). The anatomical substrate responsible for the reentry is an accessory pathway (AP) able to conduct the electrical stimulus in an anterograde, retrograde or bidirectional manner.

OBJECTIVE

To evaluate the correlation of AP location with the male and female genders and AP clinical presentation, whether manifest or concealed.

METHODS

Retrospective observational study including 942 consecutive patients, all diagnosed with EPS-confirmed AP from January 1994 to December 2008. APs were classified into eight anatomical groups: left lateral (LL), left posterior (LP), left posteroseptal (LPS), right posteroseptal (RPS), right midseptal (RMS), right anteroseptal (RAS), right lateral (RL), and right posterior (RP).

RESULTS

Of the 942 patients, 52.6% were males. The mean age was 31.2±13.8years. As regards gender, APs were more prevalent among men. However, a statistically significant difference was observed only in the LPS (p=0.029) and RL (p=0.003) regions. In relation to the form of presentation of AP, the manifest form was more frequent than the concealed form in six of the eight regions studied, except for the LL and LPS regions.

CONCLUSION

AP predominated in males and the manifest form was more frequent than the concealed form in most of the regions studied.

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.

Women and heart disease, the underrecognized burden: sex differences, biases, and unmet clinical and research challenges

For many years the significance of heart disease in women was vastly underappreciated, and women were significantly underrepresented in cardiovascular clinical research. We now know that cardiovascular disease is the leading cause of death for women. Women and men share many similarities in the pathophysiology and manifestations of heart disease. However, as research advances with the continued inclusion of more women, knowledge about gender differences between the female and male heart, both on a physiological and pathophysiological basis, grows. These differences can be found in all domains of cardiovascular health and disease, including heart rhythm, heart failure, coronary disease and valvular disease. Further understanding of gender differences in the heart is crucial for advancing our ability to maintain a healthy population and identify and treat heart disease in both women and men. Specific examples within the spectrum of heart disease will be discussed in this review paper, and areas for further research will be proposed.

The Effects of Female Sex Hormones on Ventricular Premature Beats and Repolarization Parameters in Physiological Menstrual Cycle

BACKGROUND

The effects of gender difference on cardiac electrophysiology have been well studied. In this study, we aimed to evaluate the effects of estradiol and progesteron changes occuring in physiological menstrual cycle on ventricular premature beats (VPBs) and cardiac repolarization parameters.

METHODS

Women of reproductive age with VPBs were included into the study group and healthy women were recruited as the control group. During the menstruation period, a 12-lead electrocardiography, blood samples, and 24-hour rhythm Holter were applied to the study group. Similarly, all tests were repeated in the estimated ovulation period (12-14 days before menstruation) by all cases.

RESULTS

The study group consisted of 20 women patients with VPB, and the control group of 18 healthy women. While the number of VPB in the menstruation period was 210 beats/day (interquartile range [IQR]: 1,144), it decreased to 86 beats/day (IQR: 251) in the ovulation period with statistical significance (P < 0.05). Average heart rate in the menstruation period was 81.4 ± 10 beats/min and it significantly increased to 84.6 ± 8 beats/min in the ovulation period (P < 0.05). There were no differences in cardiac repolarization parameters in both menstruation and ovulation periods between the study and control groups. Comparing the menstruation and the ovulation periods, J-Tpeak interval, which reflects early repolarization, was shorter in the ovulation period (193 ± 27.7 ms and 201.1 ± 28.6 ms, respectively; P < 0.05). Other repolarization parameters did not show any significant difference.

CONCLUSION

VPB frequency decreases with estradiol peak in the ovulation period. This suggests that estrogen may have protective effects against ventricular arrhythmias.

Deletion of Kvβ1.1 subunit leads to electrical and haemodynamic changes causing cardiac hypertrophy in female murine hearts

NEW FINDINGS

What is the central question of this study? The goal of this study was to evaluate sex differences and the role of the potassium channel β1 (Kvβ1) subunit in the heart. What is the main finding and its importance? Genetic ablation of Kvβ1.1 in females led to cardiac hypertrophy characterized by increased heart size, prolonged monophasic action potentials, elevated blood pressure and increased myosin heavy chain α (MHCα) expression. In contrast, male mice showed only electrical changes. Kvβ1.1 binds the MHCα isoform at the protein level, and small interfering RNA targeted knockdown of Kvβ1.1 upregulated MHCα. Cardiovascular disease is the leading cause of death and debility in women in the USA, and cardiac arrhythmias are a major concern. Voltage-gated potassium (Kv) channels along with the binding partners; Kvβ subunits are major regulators of the action potential (AP) shape and duration (APD). The regulation of Kv channels by the Kvβ1 subunit is unknown in female hearts. In the present study, we hypothesized that the Kvβ1 subunit is an important regulator of female cardiac physiology. To test this hypothesis, we ablated (knocked out; KO) the KCNAB1 isoform 1 (Kvβ1.1) subunit in mice and evaluated cardiac function and electrical activity by using ECG, monophasic action potential recordings and echocardiography. Our results showed that the female Kvβ1.1 KO mice developed cardiac hypertrophy, and the hearts were structurally different, with enlargement and increased area. The electrical derangements caused by Kvβ1.1 KO in female mice included long QTc and QRS intervals along with increased APD (APD20-90% repolarization). The male Kvβ1.1 KO mice did not develop cardiac hypertrophy, but they showed long QTc and prolonged APD. Molecular analysis showed that several genes that support cardiac hypertrophy were significantly altered in Kvβ1.1 KO female hearts. In particular, myosin heavy chain α expression was significantly elevated in Kvβ1.1 KO mouse heart. Using a small interfering RNA strategy, we identified that knockdown of Kvβ1 increases myosin heavy chain α expression in H9C2 cells. Collectively, changes in molecular and cell signalling pathways clearly point towards a distinct electrical and structural remodelling consistent with cardiac hypertrophy in the Kvβ1.1 KO female mice.

Sex-dependent alterations of Ca2+ cycling in human cardiac hypertrophy and heart failure

AIMS

Clinical studies have shown differences in the propensity for malignant ventricular arrhythmias between women and men suffering from cardiomyopathies and heart failure (HF). This is clinically relevant as it impacts therapies like prophylactic implantable cardioverter-defibrillator implantation but the pathomechanisms are unknown. As an increased sarcoplasmic reticulum (SR) Ca(2+) leak is arrhythmogenic, it could represent a cellular basis for this paradox.

METHODS/RESULTS

We evaluated the SR Ca(2+) leak with respect to sex differences in (i) afterload-induced cardiac hypertrophy (Hy) with preserved left ventricular (LV) function and (ii) end-stage HF. Cardiac function did not differ between sexes in both cardiac pathologies. Human cardiomyocytes isolated from female patients with Hy showed a significantly lower Ca(2+) spark frequency (CaSpF, confocal microscopy, Fluo3-AM) compared with men (P < 0.05). As Ca(2+) spark width and duration were similar in women and men, this difference in CaSpF did not yet translate into a significant difference of the calculated SR Ca(2+) leak between both sexes at this stage of disease (P = 0.14). Epifluorescence measurements (Fura2-AM) revealed comparable Ca(2+) cycling properties (diastolic Ca(2+) levels, amplitude of systolic Ca(2+) transients, SR Ca(2+) load) in patients of both sexes suffering from Hy. Additionally, the increased diastolic CaSpF in male patients with Hy did not yet translate into an elevated ratio of cells showing arrhythmic events (Ca(2+) waves, spontaneous Ca(2+) transients) (P = 0.77). In the transition to HF, both sexes showed an increase of the CaSpF (P < 0.05) and the sex dependence was even more pronounced. Female patients had a 69 ± 10% lower SR Ca(2+) leak (P < 0.05), which now even translated into a lower ratio of arrhythmic cells in female HF patients compared with men (P < 0.001).

CONCLUSION

These data show that the SR Ca(2+) leak is lower in women than in men with comparable cardiac impairment. Since the SR Ca(2+) leak triggers delayed afterdepolarizations, our findings may explain why women are less prone to ventricular arrhythmias and confirm the rationale of therapeutic measures reducing the SR Ca(2+) leak.

How cardiomyocyte excitation, calcium release and contraction become altered with age

Cardiovascular disease is the main cause of death globally, accounting for over 17 million deaths each year. As the incidence of cardiovascular disease rises markedly with age, the overall risk of cardiovascular disease is expected to increase dramatically with the aging of the population such that by 2030 it could account for over 23 million deaths per year. It is therefore vitally important to understand how the heart remodels in response to normal aging for at least two reasons: i) to understand why the aged heart is increasingly susceptible to disease; and ii) since it may be possible to modify treatment of disease in older adults if the underlying substrate upon which the disease first develops is fully understood. It is well known that age modulates cardiac function at the level of the individual cardiomyocyte. Generally, in males, aging reduces cell shortening, which is associated with a decrease in the amplitude of the systolic Ca(2+) transient. This may arise due to a decrease in peak L-type Ca(2+) current. Sarcoplasmic reticulum (SR) Ca(2+) load appears to be maintained during normal aging but evidence suggests that SR function is disrupted, such that the rate of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA)-mediated Ca(2+) removal is reduced and the properties of SR Ca(2+) release in terms of Ca(2+) sparks are altered. Interestingly, Ca(2+) handling is modulated by age to a lesser degree in females. Here we review how cellular contraction is altered as a result of the aging process by considering expression levels and functional properties of key proteins involved in controlling intracellular Ca(2+). We consider how changes in both electrical properties and intracellular Ca(2+) handling may interact to modulate cardiomyocyte contraction. We also reflect on why cardiovascular risk may differ between the sexes by highlighting sex-specific variation in the age-associated remodeling process. This article is part of a Special Issue entitled CV Aging.

Recurrence of atrial fibrillation after switching from brand to generic atenolol

Beta blockers are the initial treatment for rate control of supraventricular tachyarrhythmia in patients without a history of myocardial infarction or left ventricular dysfunction. In this article we report the recurrence of atrial fibrillation after switching to the generic formulation of atenolol.

MicroRNA-23a participates in estrogen deficiency induced gap junction remodeling of rats by targeting GJA1

Increased incidence of arrhythmias in women after menopause has been widely documented, which is considered to be related to estrogen (E2) deficiency induced cardiac electrophysiological abnormalities. However, its molecular mechanism remains incompletely clear. In the present study, we found cardiac conduction blockage in post-menopausal rats. Thereafter, the results showed that cardiac gap junctions were impaired and Connexin43 (Cx43) expression was reduced in the myocardium of post-menopausal rats. The phenomenon was also observed in ovariectomized (OVX) rats, which was attenuated by E2 supplement. Further study displayed that microRNA-23a (miR-23a) level was significantly increased in both post-menopausal and OVX rats, which was reversed by daily E2 treatment after OVX. Importantly, forced overexpression of miR-23a led to gap junction impairment and Cx43 downregulation in cultured cardiomyocytes, which was rescued by suppressing miR-23a by transfection of miR-23a specific inhibitory oligonucleotide (AMO-23a). GJA1 was identified as the target gene of miR-23a by luciferase assay and miRNA-masking antisense ODN (miR-Mask) assay. We also found that E2 supplement could reverse cardiac conduction blockage, Cx43 downregulation, gap junction remodeling and miR-23a upregulation in post-menopausal rats. These findings provide the evidence that miR-23a mediated repression of Cx43 participates in estrogen deficiency induced damages of cardiac gap junction, and highlights a new insight into molecular mechanism of post-menopause related arrhythmia at the microRNA level.

Sex differences in myosin heavy chain isoforms of human failing and nonfailing atria

Mammalian hearts express two myosin heavy chain (MHC) isoforms, which drive contractions with different kinetics and power-generating ability. The expression of the isoform that is associated with more rapid contraction kinetics and greater power output, MHC-α, is downregulated, with a concurrent increase in the relative amount of the slower isoform, MHC-β, during the progression to experimentally induced or disease-related heart failure. This change in protein expression has been well studied in right and left ventricles in heart failure models and in humans with failure. Relatively little quantitative data exists regarding MHC isoform expression shifts in human failing atria. We previously reported significant increases in the relative amount of MHC-β in the human failing left atrium. The results of that study suggested that there might be a sex-related difference in the level of MHC-β in the left atrium, but the number of female subjects was insufficient for statistical analysis. The objective of this study was to test whether there is, in fact, a sex-related difference in the level of MHC-β in the right and left atria of humans with cardiomyopathy. The results indicate that significant differences exist in atrial MHC isoform expression between men and women who are in failure. The results also revealed an unexpected twofold greater amount of MHC-β in the nonfailing left atrium of women, compared with men. The observed sex-related differences in MHC isoform expression could impact ventricular diastolic filling during normal daily activities, as well as during physiologically stressful events.

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.

Cardiac potassium channel subtypes: new roles in repolarization and arrhythmia

About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K+ channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K+ channels drive the late repolarization of the ventricle with some redundancy, and in atria this repolarization reserve is supplemented by the fairly atrial-specific KV1.5, Kir3, KCa, and K2P channels. The role of the latter two subtypes in atria is currently being clarified, and several findings indicate that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K+ channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure. The underlying posttranscriptional and posttranslational remodeling of the individual K+ channels changes their activity and significance relative to each other, and they must be viewed together to understand their role in keeping a stable heart rhythm, also under menacing conditions like attacks of reentry arrhythmia.

Ambient air pollution and daily outpatient visits for cardiac arrhythmia in Shanghai, China

Background

Cardiac arrhythmias are cardiac rhythm disorders that comprise an important public health problem. Few prior studies have examined the association between ambient air pollution and arrhythmias in general populations in mainland China.

Methods

We performed a time-series analysis to investigate the short-term association between air pollution (particulate matter with an aerodynamic diameter less than 10 µm [PM₁₀], sulfur dioxide [SO₂], and nitrogen dioxide [NO₂]) and outpatient visits for arrhythmia in Shanghai, China. We applied the over-dispersed Poisson generalized additive model to analyze the associations after control for seasonality, day of the week, and weather conditions. We then stratified the analyses by age, gender, and season.

Results

We identified a total of 56 940 outpatient visits for cardiac arrhythmia. A 10-µg/m³ increase in the present-day concentrations of PM₁₀, SO₂, and NO₂ corresponded to increases of 0.56% (95% CI 0.42%, 0.70%), 2.07% (95% CI 1.49%, 2.64%), and 2.90% (95% CI 2.53%, 3.27%), respectively, in outpatient arrhythmia visits. The associations were stronger in older people (aged ≥65 years) and in females. This study provides the first evidence that ambient air pollution is significantly associated with increased risk of cardiac arrhythmia in mainland China.

Conclusions

Our analyses provide evidence that the current air pollution levels have an adverse effect on cardiovascular health and strengthened the rationale for further limiting air pollution levels in the city.

Inflammation and prolonged QT time: results from the Cardiovascular Disease, Living and Ageing in Halle (CARLA) study

Background

Previous research found an association of CRP with QT time in population based samples. Even more, there is evidence of a substantial involvement of the tumor necrosis factor-alpha system in the pathophysiology of cardiac arrhythmia, while the role of Interleukin 6 remains inconclusive.

Objective

To determine the association between inflammation with an abnormally prolonged QT-time (APQT) in men and women of the elderly general population.

Methods

Data descend from the baseline examination of the prospective, population-based Cardiovascular Disease, Living and Ageing in Halle (CARLA) Study. After exclusion of subjects with atrial fibrillation and missing ECG recording the final study cohort consisted of 919 men and 797 women. Blood parameters of inflammation were the soluble TNF-Receptor 1 (sTNF-R1), the high-sensitive C-reactive protein (hsCRP), and Interleukin 6 (IL-6). In accordance with major cardiologic societies we defined an APQT above a QT time of 460 ms in women and 450 ms in men. Effect sizes and the corresponding 95% confidence intervals (CI) were estimated by performing multiple linear and logistic regression analyses including the analysis of sex differences by interaction terms.

Results

After covariate adjustment we found an odds ratio (OR) of 1.89 (95% CI: 1.13, 3.17) per 1000 pg/mL increase of sTNF-R1 in women, and 0.74 (95% CI: 0.48, 1.15) in men. In the covariate adjusted linear regression sTNF-R1 was again positively associated with QT time in women (5.75 ms per 1000 pg/mL, 95% CI: 1.32, 10.18), but not in men. Taking possible confounders into account IL-6 and hsCRP were not significantly related to APQT in both sexes.

Conclusion

Our findings from cross-sectional analyses give evidence for an involvement of TNF-alpha in the pathology of APQT in women.

Effectiveness of systematic screening for the detection of atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and is a leading cause of morbidity and mortality. Screening for AF in asymptomatic patients has been proposed as a way of reducing the burden of the disease by detecting people who would benefit from prophylactic anticoagulation therapy prior to the onset of symptoms. However, for screening to be an effective intervention it must improve the detection of AF and provide benefit for those who are detected earlier as a result of screening.

OBJECTIVES

The primary objective of this review was to examine whether screening programmes increase the detection of new cases of AF compared to routine practice. The secondary objectives were to identify which combination of screening strategy and patient population is most effective, as well as assessing any safety issues associated with screening, its acceptability within the target population and the costs involved.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library, MEDLINE (Ovid) and EMBASE (Ovid) up to March 2012. Other relevant research databases, trials registries and websites were searched up to June 2012. Reference lists of identified studies were also searched for potentially relevant studies and we contacted corresponding authors for information about additional published or unpublished studies that may be relevant. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials, controlled before and after studies and interrupted time series studies comparing screening for AF with routine practice in people aged 40 years and over were eligible. Two authors (PM, CT or MF) independently selected the trials for inclusion.

DATA COLLECTION AND ANALYSIS

Assessment of risk of bias and data extraction were performed independently by two authors (PM, CT). Odds ratios (OR) and 95% confidence intervals (CI) were used to present the results for the primary outcome, which is a dichotomous variable. Since only one included study was identified, no meta-analysis was performed.

MAIN RESULTS

One cluster randomised controlled trial met the inclusion criteria for this review. This study compared systematic screening (by invitation to have an electrocardiogram (ECG)) and opportunistic screening (pulse palpation during a general practitioner (GP) consultation for any reason followed by an ECG if pulse was irregular) to routine practice (normal case finding on the basis of clinical presentation) in people aged 65 years or older. The risk of bias in the included study was judged to be low.Both systematic and opportunistic screening of people over the age of 65 years are more effective than routine practice (OR 1.57, 95% CI 1.08 to 2.26 and OR 1.58, 95% CI 1.10 to 2.29, respectively). The number needed to screen in order to detect one additional case compared to routine practice was 172 (95% CI 94 to 927) for systematic screening and 167 (95% CI 92 to 806) for opportunistic screening. Both systematic and opportunistic screening were more effective in men (OR 2.68, 95% CI 1.51 to 4.76 and OR 2.33, 95% CI 1.29 to 4.19, respectively) than in women (OR 0.98, 95% CI 0.59 to 1.62 and OR 1.2, 95% CI 0.74 to 1.93, respectively). No data on the effectiveness of screening in different ethnic or socioeconomic groups were available. There were insufficient data to compare the effectiveness of screening programmes in different healthcare settings.Systematic screening was associated with a better overall uptake rate than opportunistic screening (53% versus 46%) except in the ≥ 75 years age group where uptake rates were similar (43% versus 42%). In both screening programmes men were more likely to participate than women (57% versus 50% in systematic screening, 49% versus 41% in opportunistic screening) and younger people (65 to 74 years) were more likely to participate than people aged 75 years and over (61% versus 43% systematic, 49% versus 42% opportunistic). No adverse events associated with screening were reported.The incremental cost per additional case detected by opportunistic screening was GBP 337, compared to GBP 1514 for systematic screening. All cost estimates were based on data from the single included trial, which was conducted in the UK between 2001 and 2003.

AUTHORS' CONCLUSIONS

Systematic and opportunistic screening for AF increase the rate of detection of new cases compared with routine practice. While both approaches have a comparable effect on the overall AF diagnosis rate, the cost of systematic screening is significantly more than that of opportunistic screening from the perspective of the health service provider. The lack of studies investigating the effect of screening in other health systems and younger age groups means that caution needs to be exercised in relation to the transferability of these results beyond the setting and population in which the included study was conducted.Additional research is needed to examine the effectiveness of alternative screening strategies and to investigate the effect of the intervention on the risk of stroke for screened versus non-screened populations.