Atrial fibrillation,cognition and dementia: A review

Atrial fibrillation (AF) is one of the most common types of cardiac arrhythmia, particularly among older adults. AF confers a 5‐fold risk for thromboembolic stroke as well as a 2‐fold higher risk for congestive heart failure, morbidity, and mortality. Although stroke remains an important and impactful complication of AF, recent studies have shown that AF is independently associated with other neurological disorders, including cognitive impairment and dementia, even after adjusting for prior ischemic stroke. We performed a review of the published literature on the association between AF and cognitive status. Further, we reviewed studies investigating the underlying mechanisms for this association and/or reporting the impact of AF treatment on cognitive function. While most published studies demonstrate associations between AF and impaired cognition, no AF treatment has yet been associated with a reduced incidence of cognitive decline or dementia.     

老年人亚临床甲状腺功能亢进与心房颤动

目的观察老年人亚临床甲状腺功能亢进(甲亢)与心房颤动(房颤)发生的相关性。方法观察组43例,年龄63~82岁,为亚临床性甲亢患者,即血浆甲状腺刺激激素(TSH)<0.4μU/L,游离三碘甲状腺原氨酸(FT3)、游离甲状腺素(FT4)正常,无甲亢的临床表现;对照组50例,年龄60~85岁,甲状腺功能检查正常,即0.4μU/L相似文献   

MicroRNAs与心房颤动心肌重构的研究进展

心房颤动(AF)是最常见的心律失常之一,特别在老年人中。近些年来,大量研究已经证实为非编码小RNA(miRNA)在心律失常的病理生理过程中的功能作用。本文主要就microRNAs与AF之间关系做一综述,重点在miRNAs对心肌组织电重构和结构重构的调节。     

Atrial fibrosis and substrate based characterization in atrial fibrillation: Time to move forwards

Atrial fibrillation (AF) is the most commonly encountered cardiac arrhythmia in clinical practice. However, current therapeutic interventions for atrial fibrillation have limited clinical efficacy as a consequence of major knowledge gaps in the mechanisms sustaining atrial fibrillation. From a mechanistic perspective, there is increasing evidence that atrial fibrosis plays a central role in the maintenance and perpetuation of atrial fibrillation. Electrophysiologically, atrial fibrosis results in alterations in conduction velocity, cellular refractoriness, and produces conduction block promoting meandering, unstable wavelets and micro-reentrant circuits. Clinically, atrial fibrosis has also linked to poor clinical outcomes including AF-related thromboembolic complications and arrhythmia recurrences post catheter ablation. In this article, we review the pathophysiology behind the formation of fibrosis as AF progresses, the role of fibrosis in arrhythmogenesis, surrogate markers for detection of fibrosis using cardiac magnetic resonance imaging, echocardiography and electroanatomic mapping, along with their respective limitations. We then proceed to review the current evidence behind therapeutic interventions targeting atrial fibrosis, including drugs and substrate-based catheter ablation therapies followed by the potential future use of electro phenotyping for AF characterization to overcome the limitations of contemporary substrate-based methodologies.     

老年无卒中房颤病人的痴呆发病风险及其危险因素分析

目的 探讨老年无卒中房颤病人的痴呆发病风险及其危险因素.方法 纳入2014年7月至2017年2月我院收治的113例无卒中房颤病人,按照随访其是否发生痴呆分为痴呆组和对照组.分析2组病人的临床资料、用药情况,采用多因素Logistic回归分析影响无卒中房颤病人发生痴呆的危险因素.结果 113例病人的中位随访时间为41(2...     

Atrial electrical and structural changes associated with longstanding hypertension in humans: implications for the substrate for atrial fibrillation

Atrial Remodeling in Human Hypertension Introduction: Hypertension (HT) is the most common modifiable risk factor for atrial fibrillation (AF), yet little is known of the atrial effects of chronic HT in humans. We aimed to characterize the electrophysiologic (EP) and electroanatomic (EA) remodeling of the right atrium (RA) in patients with chronically treated systemic HT and left ventricular hypertrophy (LVH) without a history of AF. Methods and Results: Twenty patients with (systolic BP 145 ± 10 mmHg) and without (BP 119 ± 11 mmHg, P < 0.01) systemic HT underwent detailed conventional EP and EA voltage and activation mapping. We measured RA refractoriness at the coronary sinus and high septum at cycle lengths (CLs) 600 and 450 ms, and RA conduction velocities, activation times, and voltages at a global and regional level at CLs 600 ms and 300 ms. HT was associated with slowing of global (73 ± 17 cm/s vs 96 ± 12 cm/s in controls, P < 0.01) and regional conduction velocity particularly in the posterior RA (70 ± 17 cm/s vs 96 ± 12 cm/s in controls, P < 0.01) at the crista terminalis (fractionation and double potentials in HT 72%± 4 vs 43%± 23 in controls, P = 0.04). Mean RA voltage was similar between the 2 groups, however HT was associated with an increase in areas of low voltage (<0.5 mV; HT 13% vs controls 9%, P = 0.04). Sustained AF was induced in 30% HT patients and no controls. Conclusion: Chronically treated systemic HT with LVH is accompanied by atrial remodeling characterized by: (i) global conduction slowing, (ii) regional conduction delay particularly at the crista terminalis, and (iii) increased AF inducibility. These changes may in part be responsible for the increased propensity to AF associated with systemic HT. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1317‐1324, December 2011)     

Atrial fibrillation: A review of mechanism,etiology, and therapy

The prevalence of elderly individuals in the populations of developed countries is increasing rapidly, and atrial fibrillation (AF) is quite common in these elderly patients: currently, 11% of the U.S. population is between the ages of 65 and 85 years; 70% of people with AF are between the ages of 65 and 85 years. AF causes symptoms secondary to hemodynamic derangements that are the result of increased ventricular response and loss of atrial booster function. AF can lead to reversible impairment of left ventricular function, cardiac chamber dilatation, clinical heart failure, and thromboembolic events. AF requires treatment in order to prevent these potential complications. Type Ia, Ic, and III antiarrhythmics are capable of converting AF to normal sinus rhythm (NSR). Amiodarone has the greatest efficacy and safety for converting AF and maintaining NSR while digoxin and verapamil are ineffective in restoring NSR. Quinidine, flecainide, disopyramide, and sotalol have also been shown to maintain NSR after conversion of AF. Proarrhythmia is a definite concern with the latter four agents. Alternative therapy for AF includes anticoagulation with warfarin or aspirin for the prevention of thromboembolic events, and a variety of agents to control the ventricular response. All medications used to treat AF carry significant risks in the elderly, whether from proarrhythmia, overdosing because of compliance errors, or hemorrhage secondary to anticoagulation. Treatment of AF must be based on a careful risk-benefit evaluation. The physician must know the capability of the particular patient as well as drug mechanisms and effects in the elderly. The decision to convert patients from AF to NSR or to leave the patient in AF and control the ventricular response represents a complex intellectual challenge. Factors favoring one or the other of these two clinical strategies are discussed. Multicenter clinical trials, for example, the Atrial Fibrillation Follow-up Investigation Rhythm Management (AFFIRM) trial, are currently underway to assess various clinical strategies for maintenance of NSR following conversion from AF. Amiodarone is one of the drugs under investigation.     

Managing anticoagulation for atrial fibrillation: current issues and future strategies

Although warfarin is superior to aspirin in reducing the risk of stroke in patients with atrial fibrillation, it can increase major bleeds. Hence, physicians stratify patients according to stroke risk to ensure a net benefit. In this review, the CHA₂DS₂‐VASc stratification scheme used in the latest European Society of Cardiology (2010/12) guidelines will be explained. The greater sensitivity of this scheme, compared to the previous CHADS₂, more closely delineates patients for whom warfarin is appropriate. The review also anticipates that there will be a wider range of patients who may benefit from the new oral anticoagulants, which show similar or superior efficacy and/or safety to warfarin with a significant reduction in intracranial haemorrhage and do not require routine coagulation monitoring. The role of conventional and new anticoagulant options will also be discussed.     

Atrial fibrillation: mechanistic insights from biatrial (and triatrial) mapping

Percutaneous radiofrequency ablation of pulmonary vein potentials has been shown to eliminate atrial fibrillation in a subset of patients characterized by frequent and repetitive paroxysms of atrial fibrillation. However, pulmonary vein disconnection has had only limited success at curing patients with persistent atrial fibrillation. In those patients, left atrial substrate modification and linear ablation strategies have had substantially higher success rates. Furthermore, in other patients, elimination of right atrial triggers (superior vena cava) or modification of right atrial substrate has been required for elimination of atrial fibrillation. Finally, the realization that the coronary sinus is a third atrial chamber that can both initiate and maintain atrial fibrillation has provided new understanding to the pathogenesis of atrial fibrillation. From a clinical perspective, only careful anatomic and mapping strategies specifically aimed at each subset of patients with atrial fibrillation will allow for pattern recognition and establish which mechanisms are responsible for initiation and maintenance of atrial fibrillation. Only the latter will allow for increased long-term success rates of ablation of atrial fibrillation.     

成纤维细胞生长因子23与心房颤动

心房颤动导致心力衰竭、卒中的发生率及死亡率明显增加,已经成为危害公众健康的重要心血管疾病,引起全社会的重视和关注。最新研究发现成纤维细胞生长因子（FGF23）可介导钙磷代谢、血管钙化、血管功能障碍和RAAS系统等途径促进心血管疾病的发生发展,并通过多种信号途径参与心肌重构及房颤的发生发展。     

A comparison of clinical characteristics and long-term prognosis in asymptomatic and symptomatic patients with first-diagnosed atrial fibrillation: The Belgrade Atrial Fibrillation Study

Background

To investigate baseline characteristics and long-term prognosis of carefully characterized asymptomatic and symptomatic patients with atrial fibrillation (AF) in a ‘real-world’ cohort of first-diagnosed non-valvular AF over a 10-year follow-up period.

Methods and results

We conducted an observational, non-interventional, and single-centre registry-based study of consecutive first-diagnosed AF patients. Of 1100 patients (mean age 52.7 ± 12.2 years and mean follow-up 9.9 ± 6.1 years), 146 (13.3%) had asymptomatic AF.Persistent or permanent AF, slower ventricular rate during AF (< 100/min), CHA₂DS₂–VASc score of 0, history of diabetes mellitus and male gender were independent baseline risk factors for asymptomatic AF presentation (all p < 0.01) with a good predictive ability of the multivariable model (c-statistic 0.86, p < 0.001).Kaplan–Meier 10-year estimates of survival free of progression of AF (log-rank test = 33.4, p < 0.001) and ischemic stroke (log-rank test = 6.2, p = 0.013) were significantly worse for patients with asymptomatic AF compared to those with symptomatic arrhythmia. In the multivariable Cox regression analysis, intermittent asymptomatic AF was significantly associated with progression to permanent AF (Hazard Ratio 1.6; 95% CI, 1.1–2.2; p = 0.009).

Conclusions

In a ‘real-world’ setting, patients with asymptomatic presentation of their first-diagnosed AF could have different risk profile and long-term outcomes compared to those with symptomatic AF. Whether more intensive monitoring and comprehensive AF management including AF ablation at early stage following the incident episode of AF and increased quality of oral anticoagulation could alter the long-term prognosis of these patients requires further investigation.     

Atrial signal analysis and defibrillation threshold assessment in chronic persistent and reinduced atrial fibrillation

INTRODUCTION: Induced versus spontaneous atrial fibrillation (AF) is of interest for assessing atrial defibrillation threshold reproducibility. METHODS AND RESULTS: Twenty-one patients with chronic AF underwent internal cardioversion with assessment of atrial defibrillation threshold at baseline and at reinduced AF. High right atrial (HRA) and coronary sinus (CS) bipolar recordings were analyzed to measure the mean local atrial period, its coefficient of variation, the 5th (P5) and 95th (P95) percentiles of atrial intervals, and the percentage of points lying at the baseline (number of occurrences), and to quantify AF organization. Atrial defibrillation threshold was comparable in baseline and reinduced AF in terms of leading-edge voltage and delivered energy. Baseline and reinduced AF were comparable with regard to overall signal parameters (both in HRA and CS) and the presence of an organized arrhythmia pattern. As for individual variables, P5 increased while P95 and coefficient of variation decreased in reinduced AF compared with spontaneous AF (statistical significance was achieved for all these parameters in HRA, but only for coefficient of variation and P95 in CS). CONCLUSION: Sustained AF reinduced after cardioversion of chronic AF is comparable with baseline AF in terms of atrial defibrillation threshold, atrial cycle length, and pattern of organization. Therefore, a clinical model based on reinduction of sustained AF after cardioversion is suitable for studying the effects of a series of interventions on atrial defibrillation threshold. However, because this model does not yield a form of AF with comparable indices of local refractoriness (e.g., P5), it is not recommended when analyzing local electrophysiologic properties.     

Atrial fibrillation and risk of dementia: a prospective cohort study

OBJECTIVES: To determine whether atrial fibrillation (AF) is associated with risk of incident dementia or Alzheimer's disease (AD), beyond its effect on stroke. DESIGN: Prospective cohort study. SETTING: An integrated healthcare delivery system. PARTICIPANTS: A population‐based sample of 3,045 community‐dwelling adults aged 65 and older without dementia or clinical stroke followed from 1994 to 2008. MEASUREMENTS: AF was identified from health plan electronic data using International Classification of Diseases, Ninth Revision, codes from inpatient and outpatient encounters. Covariates came from self‐report, study measures, and health plan data. Participants were screened every 2 years using the Cognitive Abilities Screening Instrument (range 0–100), with detailed neuropsychological and clinical assessment of those scoring less than 86. A multidisciplinary consensus committee determined diagnoses of all‐cause dementia and possible or probable AD using standard research criteria. RESULTS: AF was present in 132 (4.3%) participants at baseline and was diagnosed in 370 (12.2%) more over a mean of 6.8 years of follow‐up; 572 participants (18.8%) developed dementia (449 with AD). The adjusted hazard ratio associated with AF was 1.38 (95% confidence interval (CI)=1.10–1.73) for all‐cause dementia and 1.50 (95% CI=1.16–1.94) for possible or probable AD. Results were similar for participants with and without clinically recognized stroke during follow‐up and in sensitivity analyses examining only probable AD. CONCLUSION: AF is associated with higher risk of developing AD and dementia. Future studies should examine whether specific treatments, including optimal anticoagulation, can decrease this risk.     

Transesophageal echocardiography risk factors for stroke in nonvalvular atrial fibrillation

Atrial fibrillation is a common arrhythmia, particularly in the older age groups. It confers an increased risk of thromboembolism to these patients, and multiple clinical risk factors have been identified to be useful in predicting the risks of thromboembolic events. Recent studies have evaluated the role of transesophageal echocardiography (TEE) in the evaluation of patients with atrial fibrillation. The purpose of this review is to evaluate the significance of transesophageal echocardiographic findings in the prediction of thromboembolic events, particularly stroke, in patients with nonvalvular atrial fibrillation, with an emphasis on recently reported prospective studies. Aortic plaque and left atrial appendage abnormalities are identified as independent predictors of thromboembolic events. Although they are associated with clinical events, they also have independent incremental prognostic values. Other transesophageal echocardiographic findings, such as patent foramen ovale and atrial septal aneurysm, have not been found to be predictors of thromboembolic events in this patient group. Thus, TEE is a useful tool in stratifying patients with nonvalvular atrial fibrillation into different risk groups in terms of thromboembolic events, and it will likely play an important role in future studies to assess new treatment strategies in high-risk patients with atrial fibrillation.     

Atrial fibrillation and anticoagulation in a stroke unit population

Background:  Atrial fibrillation (AF) is an important predisposing factor for ischaemic stroke. There is evidence to suggest that even in appropriate candidates warfarin therapy is underutilized. We assessed the prevalence of AF in an Australian stroke unit to determine the degree of undertreatment at presentation.
Methods:  A retrospective analysis of all patients admitted to our Stroke Unit between October 2004 and September 2006 was carried out. All patients with a diagnosis of AF, either new or old, were then selected from this group to determine the overall prevalence and anticoagulation status. Data regarding prior stroke, stroke severity and discharge anticoagulation status were also determined.
Results:  Data from a total of 500 patients were analysed. Our results showed that AF-related strokes accounted for a large proportion (28%) of all admissions and were associated with a larger neurological deficit. Most patients (68%) with a prior diagnosis of AF without having obvious contraindications were either not anticoagulated or under-anticoagulated when presenting with an ischaemic stroke or transient ischaemic attack.
Conclusion:  Our results stress the importance of initiating and maintaining anticoagulation in patients with AF and without obvious contraindications to minimize the risk of subsequent stroke.     

Stroke risk in an elderly population with atrial fibrillation

Patients with nonvalvular atrial fibrillation (AF) have an increased risk of stroke, but the absolute rate of stroke varies widely depending on coexistent vascular disease. We assessed the stroke rate and predictive value of two published schemes for stroke risk stratification in a population-derived cohort of 259 elderly people with nonvalvular AF followed for a median of 5.3 years. The rate of ischemic stroke was 2.8% per year (95% confidence interval [CI] 1.9, 3.9). Thirty-one percent were predicted to be at low risk, and their stroke rate was 1.7% per year (95% CI 0.6, 3.8). Many people with AF in this population-derived cohort had relatively low rates of stroke. Further studies to reliably stratify stroke risk in patients with AF are needed.     

Atrial fibrillation is associated with cardiovascular events in obese Japanese with one or more cardiovascular risk factors: The Japan Morning Surge Home Blood Pressure (J‐HOP) Study

The impacts of atrial fibrillation (AF) and home blood pressure (BP) on the cardiovascular prognosis of obese individuals have not been clarified. We analyzed the differences in the prognosis (including the effect of the home BP of AF patients with/without obesity) in a Japanese population with cardiovascular risk factors. We enrolled 3,586 patients from the J‐HOP study who had at least one cardiovascular risk factor. We conducted 12‐lead electrocardiography, and the group of AF patients was determined as those whose electrocardiography revealed AF. Obesity was defined as a body mass index >25 kg/m². The primary end points were fatal/nonfatal cardiovascular events (myocardial infarction, stroke, hospitalization for heart failure, and aortic dissection). Among the obese patients, those with AF (n = 36) suffered more significantly cardiovascular events (log rank 7.17, p = .007) compared to the patients with sinus rhythm (n = 1,282), but among the non‐obese patients, the rates of cardiovascular events were similar (log rank 0.006, p = .94) in the AF patients (n = 48) and sinus rhythm patients (n = 2220). After adjusting for age, sex, office/home BP, smoking, diabetes, and creatinine level, AF was an independent predictor of cardiovascular events in the obese group (hazard ratio [HR] 3.05, 95%CI: 1.17‐7.97, p = .023). Home systolic BP was also a predictor of cardiovascular events in the obese group independent of the risk of AF (per 10 mm Hg: HR 1.36, 95%CI: 1.02‐1.83, p = .039). In conclusion, AF was an independent predictor of cardiovascular events in obese patients after adjusting for home BP.