心房颤动的流行病学研究现状及进展

心房颤动(atrial fibrillation,AF)简称房颤,是最常见的心律失常之一。为了能更好的预防房颤及其并发症,国外对该病的流行病学做了较多的研究,认为房颤的患病率和发病率均随着年龄的增长不断升高,尤其是80岁以上的老年人;男性的房颤患病率一般高于女性。房颤的危险因素不局限于既往较为公认的年龄、高血压、糖尿病、肥胖等,许多新的危险因素也陆续被发现,如高尿酸血症、阻塞性睡眠呼吸暂停、剧烈运动、气候等。我国在房颤方面的研究起步较晚,目前多局限于横断面的研究,无大规模纵断面的临床研究,和国外相比有一定的差距。房颤可导致机体发生脑卒中、心力衰竭、认知功能障碍甚至死亡。本文主要对心房颤动的流行病学研究现状及进展、发生的危险因素以及对机体的不利影响进行综述。     

Membrane fission by dynamin: what we know and what we need to know

The large GTPase dynamin is the first protein shown to catalyze membrane fission. Dynamin and its related proteins are essential to many cell functions, from endocytosis to organelle division and fusion, and it plays a critical role in many physiological functions such as synaptic transmission and muscle contraction. Research of the past three decades has focused on understanding how dynamin works. In this review, we present the basis for an emerging consensus on how dynamin functions. Three properties of dynamin are strongly supported by experimental data: first, dynamin oligomerizes into a helical polymer; second, dynamin oligomer constricts in the presence of GTP; and third, dynamin catalyzes membrane fission upon GTP hydrolysis. We present the two current models for fission, essentially diverging in how GTP energy is spent. We further discuss how future research might solve the remaining open questions presently under discussion.     

Blood pressure-lowering treatment for the prevention of cardiovascular events in patients with atrial fibrillation: An individual participant data meta-analysis

BackgroundRandomised evidence on the efficacy of blood pressure (BP)-lowering treatment to reduce cardiovascular risk in patients with atrial fibrillation (AF) is limited. Therefore, this study aimed to compare the effects of BP-lowering drugs in patients with and without AF at baseline.Methods and findingsThe study was based on the resource provided by the Blood Pressure Lowering Treatment Trialists’ Collaboration (BPLTTC), in which individual participant data (IPD) were extracted from trials with over 1,000 patient-years of follow-up in each arm, and that had randomly assigned patients to different classes of BP-lowering drugs, BP-lowering drugs versus placebo, or more versus less intensive BP-lowering regimens. For this study, only trials that had collected information on AF status at baseline were included. The effects of BP-lowering treatment on a composite endpoint of major cardiovascular events (stroke, ischaemic heart disease or heart failure) according to AF status at baseline were estimated using fixed-effect one-stage IPD meta-analyses based on Cox proportional hazards models stratified by trial. Furthermore, to assess whether the associations between the intensity of BP reduction and cardiovascular outcomes are similar in those with and without AF at baseline, we used a meta-regression. From the full BPLTTC database, 28 trials (145,653 participants) were excluded because AF status at baseline was uncertain or unavailable. A total of 22 trials were included with 188,570 patients, of whom 13,266 (7%) had AF at baseline. Risk of bias assessment showed that 20 trials were at low risk of bias and 2 trials at moderate risk. Meta-regression showed that relative risk reductions were proportional to trial-level intensity of BP lowering in patients with and without AF at baseline. Over 4.5 years of median follow-up, a 5-mm Hg systolic BP (SBP) reduction lowered the risk of major cardiovascular events both in patients with AF (hazard ratio [HR] 0.91, 95% confidence interval [CI] 0.83 to 1.00) and in patients without AF at baseline (HR 0.91, 95% CI 0.88 to 0.93), with no difference between subgroups. There was no evidence for heterogeneity of treatment effects by baseline SBP or drug class in patients with AF at baseline. The findings of this study need to be interpreted in light of its potential limitations, such as the limited number of trials, limitation in ascertaining AF cases due to the nature of the arrhythmia and measuring BP in patients with AF.ConclusionsIn this meta-analysis, we found that BP-lowering treatment reduces the risk of major cardiovascular events similarly in individuals with and without AF. Pharmacological BP lowering for prevention of cardiovascular events should be recommended in patients with AF.

In an individual patient data meta-analysis, Ana-Catarina Pinho-Gomes and colleagues investigate prevention of cardiovascular events with blood pressure-lowering treatment in those with and without atrial fibrillation.     

Association between exercise habits and stroke,heart failure,and mortality in Korean patients with incident atrial fibrillation: A nationwide population-based cohort study

BackgroundThere is a paucity of information about cardiovascular outcomes related to exercise habit change after a new diagnosis of atrial fibrillation (AF). We investigated the association between exercise habits after a new AF diagnosis and ischemic stroke, heart failure (HF), and all-cause death.Methods and findingsThis is a nationwide population-based cohort study using data from the Korea National Health Insurance Service. A retrospective analysis was performed for 66,692 patients with newly diagnosed AF between 2010 and 2016 who underwent 2 serial health examinations within 2 years before and after their AF diagnosis. Individuals were divided into 4 categories according to performance of regular exercise, which was investigated by a self-reported questionnaire in each health examination, before and after their AF diagnosis: persistent non-exercisers (30.5%), new exercisers (17.8%), exercise dropouts (17.4%), and exercise maintainers (34.2%). The primary outcomes were incidence of ischemic stroke, HF, and all-cause death. Differences in baseline characteristics among groups were balanced considering demographics, comorbidities, medications, lifestyle behaviors, and income status. The risks of the outcomes were computed by weighted Cox proportional hazards models with inverse probability of treatment weighting (IPTW) during a mean follow-up of 3.4 ± 2.0 years. The new exerciser and exercise maintainer groups were associated with a lower risk of HF compared to the persistent non-exerciser group: the hazard ratios (HRs) (95% CIs) were 0.95 (0.90–0.99) and 0.92 (0.88–0.96), respectively (p < 0.001). Also, performing exercise any time before or after AF diagnosis was associated with a lower risk of mortality compared to persistent non-exercising: the HR (95% CI) was 0.82 (0.73–0.91) for new exercisers, 0.83 (0.74–0.93) for exercise dropouts, and 0.61 (0.55–0.67) for exercise maintainers (p < 0.001). For ischemic stroke, the estimates of HRs were 10%–14% lower in patients of the exercise groups, yet differences were statistically insignificant (p = 0.057). Energy expenditure of 1,000–1,499 MET-min/wk (regular moderate exercise 170–240 min/wk) was consistently associated with a lower risk of each outcome based on a subgroup analysis of the new exerciser group. Study limitations include recall bias introduced due to the nature of the self-reported questionnaire and restricted external generalizability to other ethnic groups.ConclusionsInitiating or continuing regular exercise after AF diagnosis was associated with lower risks of HF and mortality. The promotion of exercise might reduce the future risk of adverse outcomes in patients with AF.

Using a population-based cohort study, Dr. Choi and colleagues studied patients with atrial fibrillation to determine whether their exercise habits were associated with occurrence of ischemic stroke, heart failure, and all-cause mortality.     

Therapeutic options for patients with advanced atrial fibrillation: from lifestyle and medication to catheter and surgical ablation

Atrial fibrillation (AF) is part of a vicious cycle that includes multiple cardiovascular risk factors and comorbidity which can promote atrial remodelling and AF progression. Most AF-related risk factors—hypertension, diabetes, sleep apnoea, obesity and sedentary lifestyle—are in essence modifiable which may prevent AF development. Treatment of associated cardiovascular conditions may prevent both symptoms and future cardiovascular events. For advanced forms of symptomatic AF refractory to lifestyle management and optimal medication, invasive ablation therapies have become a cornerstone. Although electrical trigger isolation from the pulmonary veins is reasonably effective and safe, more potent energy sources including high output-short duration radiofrequency, ultra-low cryo-energy, and electroporation, as well as more sophisticated arrays, balloons, and lattice-tipped catheter tools, are on their way to eliminate existing pitfalls and simplify the procedure. Electroanatomical navigation and mapping systems are becoming available to provide real-time information on ablation lesion quality and the critical pathways of AF in the individual patient to guide more extensive ablation strategies that may enhance long-term outcome for freedom of advanced AF. Surgical techniques, either stand-alone or concomitant to structural cardiac repair, hybrid, or convergent, with novel less invasive access options are developing and can be helpful in situations unsuitable for catheter ablation.

     

Non-Alcoholic Fatty Liver Disease as a Predictor of Atrial Fibrillation in Middle-Aged Population (OPERA Study)

Non-alcoholic fatty liver disease (NAFLD) and atrial fibrillation (AF) are widespread diseases and have multiple common risk factors and comorbidities. No studies of association between ultrasonography-diagnosed NAFLD and AF exist in other than diabetic population. The goal of this prospective study was to study the value of NAFLD as a predictor of atrial fibrillation. This study had 958 subjects from the OPERA (Oulu Project Elucidating Risk of Atherosclerosis) cohort, and the mean follow-up time was 16.3 years. NAFLD was diagnosed if the subject had fatty liver in ultrasonography and no excess alcohol intake. AF was followed in the National Registers. In this study 249 subjects (26.0%) had NAFLD and 37 (14.9%) of these had AF whereas only 56 (7.9%) of those without NAFLD experienced AF during the follow-up time (p = 0.001). In the multiple Cox regression analysis including potential confounders (age, sex, study group, diabetes, body mass index (BMI), waist circumference, alcohol consumption, smoking, serum alanine aminotransferase concentration (ALT), systolic blood pressure, quick index, left ventricular mass index, left atrial diameter, coronary artery disease (CAD), atrial natriuretic peptide (ANP) and high sensitive C-reactive protein (hs-CRP)), NAFLD remained as an independent predictor of AF (Adjusted OR, 1.88 (95% Confidence interval (CI) 1.03–3.45)). In conclusion, our data shows that NAFLD is independently associated with the risk of AF.     

Comparable Ascertainment of Newly-Diagnosed Atrial Fibrillation Using Active Cohort Follow-Up versus Surveillance of Centers for Medicare and Medicaid Services in the Atherosclerosis Risk in Communities Study

Objective

Increasingly, epidemiologic studies use administrative data to identify atrial fibrillation (AF). Capture of incident AF is not well documented. We examined incidence rates and concordance of AF diagnosis based on active cohort follow-up versus surveillance of Centers for Medicare and Medicaid Services data in the Atherosclerosis Risk in Communities study.

Methods

Atherosclerosis Risk in Communities cohort participants without prevalent AF enrolled in fee-for-service Medicare, with inpatient and outpatient coverage, for at least 12 continuous months between 1991 and 2009 were included. In active Atherosclerosis Risk in Communities study follow-up, annual telephone calls captured hospitalizations and deaths with incident AF diagnosis codes. For Centers for Medicare and Medicaid Services data, incident AF was defined by billed inpatient and outpatient diagnoses.

Results

Of 10,134 eligible cohort participants, 738 developed AF according to both Atherosclerosis Risk in Communities and Centers for Medicare and Medicaid Services data; an additional 93 and 288 incident cases were identified using only Atherosclerosis Risk in Communities and Centers for Medicare and Medicaid Services data, respectively. Incidence rates per 1,000 person-years were 10.8 (95% confidence interval: 10.1–11.6) and 13.6 (95% confidence interval: 12.8–14.4) in Atherosclerosis Risk in Communities and Centers for Medicare and Medicaid Services, respectively; agreement was 96%; kappa was 0.77 (95% confidence interval: 0.75–0.80). Earlier AF ascertainment by one system versus the other was not associated with any cardiovascular disease risk factors, after accounting for sociodemographic factors. Additional Centers for Medicare and Medicaid Services events did not alter observed associations between risk factors and AF.

Conclusion

Among fee-for-service enrollees, AF incidence rates were slightly lower for active cohort follow-up than for Centers for Medicare and Medicaid Services surveillance, because the latter included outpatient atrial fibrillation. Concordance was high and combining the two approaches could provide a more complete picture of newly-diagnosed AF.     

Atrial remodeling in atrial fibrillation and association between microRNA network and atrial fibrillation

Atrial fibrillation (AF) remains one of the leading causes of morbidity and mortality in the world which are related to palpitations, fainting, congestive heart failure or stroke. The mechanism for atrial fibrillation has been identified as electrical remodeling, structure remodeling and intracellular calcium handling remodeling. microRNAs (miRNAs) have recently emerged as one of the important factors in regulating gene expression. So far, thousands of miRNA genes have been found in diverse animals with the function of regulating cell death, cell proliferation, haematopoiesis and even participate in the processing of cardiovascular disease. In this review, we summarize the mechanism of AF and the association of microRNAs network with AF. We provide a potential perspective of miRNAs as the therapeutic target for AF.     

Echocardiographic Measures of Cardiac Structure and Function Are Associated with Risk of Atrial Fibrillation in Blacks: The Atherosclerosis Risk in Communities (ARIC) Study

Background

Several studies have examined the link between atrial fibrillation (AF) and various echocardiographic measures of cardiac structure and function in whites and other racial groups but not in blacks. Exploring AF risk factors in blacks is important given that the lower incidence of AF in this racial group despite higher risk factors, is not completely explained.

Methods

We examined the association of echocardiographic measures with AF incidence in 2283 blacks (64.5% women, mean age 58.8 years) free of diagnosed AF and enrolled in the Jackson cohort of Atherosclerosis Risk in Communities (ARIC) study, a prospective study of cardiovascular disease. Echocardiography was performed in 1993–1995, and incident AF was determined by electrocardiograms at a follow-up study exam, hospitalization discharge codes and death certificates through the end of 2009. Cox proportional hazards regression was used to estimate hazard ratios and 95% confidence intervals for AF associated with the echocardiographic measures, adjusting for age, sex, and known AF risk factors.

Results

During an average follow-up of 13.5 years, 191 (8.4%) individuals developed AF. Left ventricular (LV) internal diameter 2-D (diastole) and percent fractional shortening of LV diameter displayed a U-shaped relationship with risk of AF, while left atrial diameter displayed a J-shaped nonlinear association. LV mass index was associated positively with AF. E/A ratio <0.7 or >1.5 and ejection fraction (EF <50%) were also associated with higher AF risk. These measures improved risk stratification for AF in addition to traditional risk factors, although not significantly {C-statistic of 0.767 (0.714–0.819) vs. 0.744 (0.691–0.797)}.

Conclusions

In a community-based population of blacks, echocardiographic measures of cardiac structure and function are significantly associated with an increased risk of AF.     

Deciphering the Leishmania exoproteome: what we know and what we can learn

Parasitic protozoa of the genus Leishmania are the causative agents of leishmaniasis. Survival and transmission of these parasites in their different hosts require membrane-bound or extracellular factors to interact with and modify their host environments. Over the last decade, several approaches have been applied to study all the extracellular proteins exported by an organism at a particular time or stage in its life cycle and under defined conditions, collectively termed the secretome or the exoproteome. In this review, we focus on emerging data shedding light on the secretion mechanisms involved in the production of the Leishmania exoproteome. We also describe other methodologies currently available that could be used to analyse the Leishmania exoproteome. Understanding the complexity of the Leishmania exoproteome is a key component to elucidating the mechanisms used by these parasites for exporting proteins to the extracellular space during its life cycle. Given the importance of extracellular factors, a detailed knowledge of the Leishmania exoproteome may provide novel targets for rational drug design and/or a source of antigens for vaccine development.     

Effects of aldosterone and mineralocorticoid receptor antagonism on cardiac ion channels in the view of upstream therapy of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia in man. Over the past years, importance of the renin-angiotensin-aldosterone system in AF pathophysiology has been recognized. Lately, the role of aldosterone in AF pathophysiology and mineralocorticoid receptor (MR) antagonism in "upstream" AF treatment is discussed with special regards concerning the effects on AF-induced structural remodeling. However, there is more and more evidence that MR antagonism also influences atrial electrophysiology and, respectively, AF-induced electrical remodeling, whereas the molecular mechanisms are almost unknown. The aim of this mini-review is to give an overview about the role of aldosterone in AF pathophysiology in principle and to summarize current available data concerning affection of cardiac ion channels by aldosterone and MR antagonism. Finally, as modulation of oxidative stress is discussed as one main therapy principle of "upstream" treatment of AF, potential mechanisms how modulation of oxidative stress by aldosterone and accordingly MR antagonism might alter atrial ion currents are delineated. Summarized, publications concerning potential mechanisms of aldosterone- and MR antagonism-modulated cardiac ion channels in various experimental settings are almost exclusively limited to the ventricular level and, partly, they are also contradictorily. Translation of these data to the atria is problematic because atrial and ventricular electrophysiology exhibit remarkable differences. It can be concluded that further research on the "atrial level" is needed in order to clarify the potential impact of the affection of atrial ion channels by aldosterone and accordingly MR antagonism in "upstream" therapy of AF.     

房颤射频消融术后复发风险预测评分系统的建立及评价

目的:探讨心房颤动(房颤)患者射频消融术后复发的风险因素,并依此构建个性化的风险评分系统。方法:选取2017年1~8月行射频消融术的房颤患者154例作为研究对象,依据术后3个月的随访结果将患者分为复发组及未复发组,采用单因素分析和Logistic回归分析对各风险因素进行分析,构建其评分系统,采用Hosmer-Lemeshow拟合优度检验和ROC曲线下面积评价评分系统的准确度及区分度。结果:术后随访3个月的结果显示共37例(24.03%)房颤患者出现复发,房颤类型、病程、体质量指数(BMI)、左房前后径(LAD)、左房容积(LAV)及超敏C反应蛋白(hs-CRP)水平均是房颤复发的独立风险因素(P<0.05)。构建的风险评分系统得分为0~26分,Hosmer-Lemeshow拟合优度检验:x^2=7.520,P=0.482;ROC曲线下面积为0.864(95%CI:0.837~0.891),预测评分值为15分时,约登指数最大(0.605),此时的敏感度和特异度分别为77.3%和83.2%。结论:房颤患者射频消融术后的复发率较高,依据风险因素构建的风险评分系统具有较高的预测效率和区分能力,可作为房颤患者射频消融术后复发风险评估的参考工具。     

Breast cancer genetics: what we know and what we need

Breast cancer results from genetic and environmental factors leading to the accumulation of mutations in essential genes. Genetic predisposition may have a strong, almost singular effect, as with BRCA1 and BRCA2, or may represent the cumulative effects of multiple low-penetrance susceptibility alleles. Here we review high- and low-penetrance breast-cancer-susceptibility alleles and discuss ongoing efforts to identify additional susceptibility genes. Ultimately these discoveries will lead to individualized breast cancer risk assessment and a reduction in breast cancer incidence.     

Rate of cardiac arrhythmias and silent brain lesions in experienced marathon runners: rationale, design and baseline data of the Berlin Beat of Running study

ABSTRACT: BACKGROUND: Regular exercise is beneficial for cardiovascular health but a recent meta-analysis indicated a relationship between extensive endurance sport and a higher risk of atrial fibrillation, an independent risk factor for stroke. However, data on the frequency of cardiac arrhythmias or (clinically silent) brain lesions during and after marathon running are missing.Methods/ DesignIn the prospective observational "Berlin Beat of Running" study experienced endurance athletes underwent clinical examination (CE), 3 Tesla brain magnetic resonance imaging (MRI), carotid ultrasound imaging (CUI) and serial blood sampling (BS) within 2-3 days prior (CE, MRI, CUI, BS), directly after (CE, BS) and within 2 days after (CE, MRI, BS) the 38th BMW BERLIN-MARATHON 2011. All participants wore a portable electrocardiogram (ECG)-recorder throughout the 4 to 5 days baseline study period. Participants with pathological MRI findings after the marathon, troponin elevations or detected cardiac arrhythmias will be asked to undergo cardiac MRI to rule out structural abnormalities. A follow-up is scheduled after one year. RESULTS: Here we report the baseline data of the enrolled 110 athletes aged 36-61 years. Their mean age was 48.8 [PLUS-MINUS SIGN] 6.0 years, 24.5 % were female, 8.2 % had hypertension and 2.7 % had hyperlipidaemia. Participants have attended a mean of 7.5 [PLUS-MINUS SIGN] 6.6 marathon races within the last 5 years and a mean of 16 [PLUS-MINUS SIGN] 36 marathon races in total. Their weekly running distance prior to the 38th BMW BERLIN-MARATHON was 65 [PLUS-MINUS SIGN] 17 km. Finally, 108 (98.2 %) Berlin Beat-Study participants successfully completed the 38th BMW BERLIN-MARATHON 2011. DISCUSSION: Findings from the "Berlin Beats of Running" study will help to balance the benefits and risks of extensive endurance sport. ECG-recording during the marathon might contribute to identify athletes at risk for cardiovascular events. MRI results will give new insights into the link between physical stress and brain damage.Trial registrationclinicaltrials.gov NCT01428778.     

Assessment of the causal relevance of ECG parameters for risk of atrial fibrillation: A mendelian randomisation study

BackgroundAtrial electrical and structural remodelling in older individuals with cardiovascular risk factors has been associated with changes in surface electrocardiographic (ECG) parameters (e.g., prolongation of the PR interval) and higher risks of atrial fibrillation (AF). However, it has been difficult to establish whether altered ECG parameters are the cause or a consequence of the myocardial substrate leading to AF. This study aimed to examine the potential causal relevance of ECG parameters on risk of AF using mendelian randomisation (MR).Methods and findingsWeighted genetic scores explaining lifelong differences in P-wave duration, PR interval, and QT interval were constructed, and associations between these ECG scores and risk of AF were estimated among 278,792 UK Biobank participants (mean age: 57 years at recruitment; 19,132 AF cases). The independent genetic variants contributing to each of the separate ECG scores, and their corresponding weights, were based on published genome-wide association studies. In UK Biobank, genetic scores representing a 5 ms longer P-wave duration or PR interval were significantly associated with lower risks of AF (odds ratio [OR] 0.91; 95% confidence interval [CI]: 0.87–0.96, P = 2 × 10⁻⁴ and OR 0.94; 95% CI: 0.93–0.96, P = 2 × 10⁻¹⁹, respectively), while longer QT interval was not significantly associated with AF. These effects were independently replicated among a further 17,931 AF cases from the AFGen Consortium. Investigation of potential mechanistic pathways showed that differences in ECG parameters associated with specific ion channel genes had effects on risk of AF consistent with the overall scores, while the overall scores were not associated with changes in left atrial size. Limitations of the study included the inherent assumptions of MR, restriction to individuals of European ancestry, and possible restriction of results to the normal ECG ranges represented in UK Biobank.ConclusionsIn UK Biobank, we observed evidence suggesting a causal relationship between lifelong differences in ECG parameters (particularly PR interval) that reflect longer atrial conduction times and a lower risk of AF. These findings, which appear to be independent of atrial size and concomitant cardiovascular comorbidity, support the relevance of varying mechanisms underpinning AF and indicate that more individualised treatment strategies warrant consideration.

In a Mendelian randomization analysis, Parag Gajendragadkar and colleagues investigate associations between genetically-predicted EEG parameters and risk of atrial fibrillation among UK Biobank participants.     

Newly Diagnosed Atrial Fibrillation Is an Independent Factor for Future Major Adverse Cardiovascular Events

Objectives

This study aims to investigate the impact of newly diagnosed atrial fibrillation (AF) on future major adverse cardiac events (MACE). AF is the most common form of cardiac arrhythmia and is associated with several other cardiovascular (CV) events. Little is known about whether newly diagnosed AF is an independent factor for future MACE, especially in patients without such a history.

Methods and Results

We evaluated data from the National Health Insurance Research Database, which represented a retrospective cohort of 713,288 adults in Taiwan from 2006 to 2010. Individuals with previous MACE were excluded. Newly diagnosed AF patients were identified by assigning International Classification of Diseases codes. Propensity score matching adjusted for gender, age, hypertension, diabetes mellitus and dyslipidemia. Cox proportional hazard models estimated future MACE ratios. We compared a total of 3,737 patients with newly diagnosed AF and 704,225 patients without. After matching, there was no difference in baseline demographic characteristics in patients across newly diagnosed AF and non-AF groups. The result showed that newly diagnosed AF in multivariate analysis were associated with increased incidents of MACE (hazard ratio: 3.11-3.51 in different models) and mortality. Newly diagnosed AF without other CV risk factors had 8.45 times the risk of developing future MACE than healthy adults. The more associated CV risk factors in addition to AF, the increased rate of future CV events.

Conclusions

Newly diagnosed AF is an independent factor that leads to future CV events after gender, age, hypertension, diabetes mellitus and dyslipidemia matching. AF is associated with a higher mortality rate.     

Polysomnography in AF patients without prior diagnosis of obstructive sleep apnea reveals significant sleep abnormality: A strong case for screening in all patients with atrial fibrillation?

BackgroundObstructive sleep apnea (OSA) and atrial fibrillation (AF) are known to often coexist together. However, whether all patients with AF should be screened for sleep abnormalities is not clear. No previous study has examined the association of asymptomatic OSA with AF.ObjectiveThis study sought to determine the prevalence of asymptomatic OSA in patients with persistent AF and whether asymptomatic OSA is an independent risk factor for atrial fibrillation.MethodPatients with persistent AF without a prior diagnosis of OSA and asymptomatic for sleep abnormalities were prospectively enrolled over 12 months. All patients underwent polysomnography after informed consent. Patients without AF or OSA who underwent polysomnography during the same period served as controls.ResultsA total of 97 patients were studied; 50 were in the case group (patients with persistent AF) and 47 were in the control group (patients in sinus rhythm). Asymptomatic OSA was diagnosed on polysomnography in 72% of patients in the AF group and 17% of the control population. Multivariable analysis of factors including diabetes, hypertension, coronary artery disease, hypothyroidism, prior MI, and asymptomatic OSA, suggested asymptomatic OSA as an independent factor associated with AF.ConclusionA significant proportion (72%) of patients with persistent AF have underlying asymptomatic OSA. Sleep abnormality thus has a strong association with AF even in patients who are asymptomatic for OSA. Screening for OSA may be advised for all patients with AF, as this may have significant implications for management.     

Gender in atrial fibrillation: Ten years later

Background: Atrial fibrillation (AF) is the most common arrhythmia encountered in both male and female patients.Objective: This evidence-based update attempts to address the advances in the science of AF management in light of key gender issues.Methods: In October 2009, 2 investigators (H.I.M. and B.D.P.) independently searched MEDLINE (PubMed [1950–2009] and Ovid [2000–2009]) for all publication types in the English language, using database-specific controlled vocabulary describing the concepts of AF and gender (atrial fibrillation, gender, women, and men for PubMed; atrial fibrillation and gender for Ovid). The reference sections from the identified publications were also used. The methodologic quality of publications, their content relevance, and the authors' expert opinions guided publication inclusion in this evidence-based narrative review. Articles relevant to gender differences in pathophysiology, outcomes, and treatment of AF are summarized and discussed.Results: Based on current available data, mortality is greater for women with AF than for men with AF. Women with AF have a higher risk of stroke compared with their male counterparts. Women derive the greatest benefit from anticoagulation in AF. There are no significant sex differences in major bleeding risk from warfarin. Women tend to be more symptomatic from AF than are men, but fare worse than men when a rhythm-control strategy is utilized with antiarrhythmic medications. Women have an increased risk for torsades de pointes when taking sotalol or dofetilide, and have a higher risk of bradyarrhythmias when taking antiarrhythmics. AF catheter ablation is successful and beneficial for selected patients of both sexes, although women may incur higher procedural bleeding complications. Women tend to be referred for AF ablation less and later than are men.Conclusions: The past decade has witnessed significant progress in the understanding and management of AF. Awareness of key sex-specific differences in AF allows for a more safe, effective, and personalized approach to the management of this disorder.     

The origin of life: what we know,what we can know and what we will never know

The origin of life (OOL) problem remains one of the more challenging scientific questions of all time. In this essay, we propose that following recent experimental and theoretical advances in systems chemistry, the underlying principle governing the emergence of life on the Earth can in its broadest sense be specified, and may be stated as follows: all stable (persistent) replicating systems will tend to evolve over time towards systems of greater stability. The stability kind referred to, however, is dynamic kinetic stability, and quite distinct from the traditional thermodynamic stability which conventionally dominates physical and chemical thinking. Significantly, that stability kind is generally found to be enhanced by increasing complexification, since added features in the replicating system that improve replication efficiency will be reproduced, thereby offering an explanation for the emergence of life''s extraordinary complexity. On the basis of that simple principle, a fundamental reassessment of the underlying chemistry–biology relationship is possible, one with broad ramifications. In the context of the OOL question, this novel perspective can assist in clarifying central ahistoric aspects of abiogenesis, as opposed to the many historic aspects that have probably been forever lost in the mists of time.