Atrial fibrillation as a risk factor for cognitive impairment: a semi-systematic review

Impact and Implications of Neurocognitive Dysfunction in the Management of Ischemic Heart Failure

Neurocognitive dysfunction is common in heart failure (HF), with 30% to 80% of patients experiencing some degree of deficits in one or more cognitive domains, including memory, attention, learning ability, executive function, and psychomotor speed. Although the mechanism is not fully understood, reduced cardiac output, comorbidities, chronic cerebral hypoperfusion, and cardioembolic brain injury leading to cerebral hypoxia and brain damage seem to trigger the neurocognitive dysfunction in HF. Cognitive impairment is independently associated with worse outcomes including mortality, rehospitalization, and reduced quality of life. Patients with poorer cognitive function are at an increased risk of severe disease as they tend to have greater difficulty complying with treatment requirements. Coronary revascularization in patients with ischemic HF has the potential to improve cardiovascular outcomes but risks worsening neurocognitive dysfunction even further. Revascularization by coronary artery bypass grafting carries inherent risks for delirium, cognitive impairment, neurologic injury, and stroke, which are known to exacerbate the risk of neurocognitive dysfunction. Alternatively, percutaneous coronary intervention, as a less-invasive approach, has the potential to minimize the risk of cognitive impairment but has not yet been evaluated as an alternative to coronary artery bypass grafting in patients with ischemic HF. Therefore, it is paramount to raise awareness of the neurocognitive consequences in ischemic HF and devise strategies for recognition and prevention as an important target of patient management and personalized decision making that contributes to patient outcomes.

IKACh is constitutively active via PKC epsilon in aging mediated atrial fibrillation

Atrial fibrillation (AF), the most common abnormal heart rhythm, is a major cause for stroke. Aging is a significant risk factor for AF; however, specific ionic pathways that can elucidate how aging leads to AF remain elusive. We used young and old wild-type and PKC epsilon- (PKCϵ) knockout mice, whole animal, and cellular electrophysiology, as well as whole heart, and cellular imaging to investigate how aging leads to the aberrant functioning of a potassium current, and consequently to AF facilitation. Our experiments showed that knocking out PKCϵ abrogates the effects of aging on AF by preventing the development of a constitutively active acetylcholine sensitive inward rectifier potassium current (IKACh). Moreover, blocking this abnormal current in the old heart reduces AF inducibility. Our studies demonstrate that in the aging heart, IKACh is constitutively active in a PKCϵ-dependent manner, contributing to the perpetuation of AF.

Rhythm Control Better Prevents Dementia than Rate Control Strategies in Patients with Atrial Fibrillation-A Nationwide Cohort Study

Background: Atrial fibrillation (AF) increases the risk of dementia. Whether the pharmacological rhythm control of AF can reduce the risk of dementia compared to the rate control strategy remains unclear. We hypothesize that the rhythm control strategy is better than the rate control strategy in preventing dementia. Methods: AF patients aged ≥65 years were identified from the Taiwan National Health Insurance Database. Patients receiving anti-arrhythmic drugs at a cumulative defined daily dose (cDDD) of >30 within the first year of enrollment constituted the rhythm control group. Patients who used rate control medications for a cDDD of >30 constituted the rate control group. A multivariate Cox hazards regression model was used to determine the hazard ratio (HR) for dementia. Results: A total of 3382 AF patients (698 in the rhythm control group; 2684 in the rate control group) were analyzed. During a 4.86 ± 3.38 year follow-up period, 414 dementia events occurred. The rhythm control group had a lower rate of dementia than the rate control group (adjust HR: 0.75, p = 0.031). The rhythm control strategy reduced the risk of dementia particularly in those receiving aspirin (p = 0.03). Conclusions: In patients with AF, pharmacological rhythm control was associated with a lower risk of dementia than rate control over a long-term follow-up period, particularly in patients receiving aspirin treatment.

Frequent Premature Atrial Contractions Are Associated With Poorer Cognitive Function in the Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

To evaluate the association of premature atrial contraction (PAC) frequency with cognitive test scores and prevalence of dementia or mild cognitive impairment (MCI).

MATERIALS AND METHODS

We conducted a cross-sectional analysis using Atherosclerosis Risk in Communities study visit 6 (January 1, 2016, through December 31, 2017) data. We included 2163 participants without atrial fibrillation (AF) (age mean ± SD, 79±4 years; 1273 (58.9%) female; and 604 (27.97.0% Black) who underwent cognitive testing and wore a leadless, ambulatory electrocardiogram monitor for 14 days. We categorized PAC frequency based on the percent of beats: less than 1%, minimal; 1% to <5%, occasional; greater than or equal to 5%, frequent. We derived cognitive domain-specific factor scores (memory, executive function, language, and global z-score). Dementia and MCI were adjudicated.

RESULTS

During a mean analyzable time of 12.6±2.6 days, 339 (15.7%) had occasional PACs and 107 (4.9%) had frequent PACs. Individuals with frequent PACs (vs minimal) had lower executive function factor scores by 0.30 (95% CI, -0.46 to -0.14) and lower global factor scores by 0.20 (95% CI, -0.33 to -0.07) after multivariable adjustment. Individuals with frequent PACs (vs minimal) had higher odds of prevalent dementia or MCI after multivariable adjustment (odds ratio, 1.74; 95% CI, 1.09 to 2.79). These associations were unchanged with additional adjustment for stroke.

CONCLUSION

In community-dwelling older adults without AF, frequent PACs were cross-sectionally associated with lower executive and global cognitive function and greater prevalence of dementia or MCI, independently of stroke. Our findings lend support to the notion that atrial cardiomyopathy may be a driver of AF-related outcomes. Further research to confirm these associations prospectively and to elucidate underlying mechanisms is warranted.

Oral anticoagulants for nonvalvular atrial fibrillation in frail elderly patients: insights from the ARISTOPHANES study

BACKGROUND

Patient frailty amongst patients with nonvalvular atrial fibrillation (NVAF) is associated with adverse health outcomes and increased risk of mortality. Additional evidence is needed to evaluate effective and safe NVAF treatment in this patient population.

OBJECTIVES

This subgroup analysis of the ARISTOPHANES study compared the risk of stroke/systemic embolism (S/SE) and major bleeding (MB) amongst frail NVAF patients prescribed nonvitamin K antagonist oral anticoagulants (NOACs) or warfarin.

METHODS

This comparative retrospective observational study of frail, older NVAF patients who initiated apixaban, dabigatran, rivaroxaban or warfarin from 01JAN2013-30SEP2015 was conducted using Medicare and 3 US commercial claims databases. To compare each drug, 6 propensity score-matched (PSM) cohorts were created. Patient cohorts were pooled from 4 databases after PSM. Cox models were used to estimate hazard ratios (HR) of S/SE and MB.

RESULTS

Amongst NVAF patients, 34% (N = 150 487) met frailty criteria. Apixaban and rivaroxaban were associated with a lower risk of S/SE vs warfarin (apixaban: HR: 0.61, 95% CI: 0.55-0.69; rivaroxaban: HR: 0.79, 95% CI: 0.72-0.87). For MB, apixaban (HR: 0.62, 95% CI: 0.57-0.66) and dabigatran (HR: 0.79, 95% CI: 0.70-0.89) were associated with a lower risk and rivaroxaban (HR: 1.14, 95% CI: 1.08-1.21) was associated with a higher risk vs warfarin.

CONCLUSION

Amongst this cohort of frail NVAF patients, NOACs were associated with varying rates of stroke/SE and MB compared with warfarin. Due to the lack of real-world data regarding OAC treatment in frail patients, these results may inform clinical practice in the treatment of this patient population.

Antithrombotic therapy and the risk of new-onset dementia in elderly patients with atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is associated with an increased risk of dementia. Little is known about the relationship of antithrombotic therapy and the risk of dementia in patients with AF without clinical stroke.

METHOD

This was an observational study based on a hospital AF registry. Patients aged 65-85 years at the time of AF diagnosis were identified via the computerised database of the clinical management system. Patients with prior stroke or known cognitive dysfunction were excluded. The primary outcome was newly diagnosed dementia during the follow-up period.

RESULTS

3284 patients (mean age 76.4±5.3 years, 51.6% male) were included for analysis. The mean CHA₂DS₂-VASc score was 3.94±1.44. 18.5% patients were prescribed warfarin, 39.8% were prescribed aspirin and 41.7% were prescribed no antithrombotic therapy. After a mean follow-up of 3.6 years, 71 patients (2.2%) developed dementia, giving rise to an incidence of 0.61%/year. The incidence of dementia were 1.04%/year, 0.69%/year and 0.14%/year for patients on no therapy, aspirin and warfarin, respectively. Both univariate and multivariate analyses showed that age ≥75 years, female gender and high CHA₂DS₂-VASc score were associated with significantly higher risk of dementia; warfarin use was associated with significantly lower risk of dementia (HR: 0.14%, 95% CI 0.05 to 0.36, p<0.001). Patients on warfarin with time in therapeutic range (TTR) ≥65% had a non-significant trend towards a lower risk of dementia compared with those with TTR <65%.

CONCLUSION

In elderly AF patients, warfarin therapy was associated with a significantly lower risk of new-onset dementia compared those with no therapy or aspirin.

Stroke prevention strategies in high-risk patients with atrial fibrillation

Effective stroke prevention with oral anticoagulation (OAC) is the cornerstone of the management of patients with atrial fibrillation. The use of OAC reduces the risk of stroke and death. For most patients with atrial fibrillation without moderate or severe mitral valve stenosis or prosthetic mechanical heart valves, treatment options include vitamin K antagonists, such as warfarin, and non-vitamin K antagonist oral anticoagulants (NOACs). Although most guidelines generally recommend NOACs as the first-line OAC, caution is required in some groups of patients with atrial fibrillation at high risk of stroke and bleeding who have been under-represented or not studied in the randomized clinical trials on NOACs for stroke prevention. In addition to OAC, non-pharmacological, percutaneous therapies, including left atrial appendage occlusion, for stroke prevention have emerged, sometimes used in combination with catheter ablation for the treatment of the atrial fibrillation. High-risk groups of patients with atrial fibrillation include patients with end-stage renal failure (including those receiving dialysis), extremely old patients (such as those aged >80 years with multiple risk factors for bleeding), patients with dementia or those living in a long-term care home, patients with previous intracranial bleeding or recent acute bleeding (such as gastrointestinal bleeding), patients with acute ischaemic stroke and patients with an intracardiac thrombus. This Review provides an overview of stroke prevention strategies, including left atrial appendage occlusion, in patients with atrial fibrillation at high risk of stroke and bleeding.

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

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

Atrial Fibrillation and Cognitive Impairment: An Associated Burden or Burden by Association?

Growing evidence suggests that atrial fibrillation (AF), in addition to its thromboembolic risk, is a risk factor for cognitive impairment (CI) via several pathways and mechanisms, further contributing to morbidity/mortality. Prior stroke is a contributor to CI, but AF is also associated with CI independently from prior stroke. Silent brain infarctions, microemboli and microbleeds, brain atrophy, cerebral hypoperfusion from widely fluctuating ventricular rates, altered hemostatic function, vascular oxidative stress, and inflammation may all exacerbate CI, particularly in patients with persistent/permanent rather than paroxysmal AF and with increased duration/burden of the arrhythmia. Brain magnetic resonance imaging is an important screening tool in eliciting and monitoring vascular and nonvascular lesions contributing to CI. Evidence is also emerging about the role of genetics in CI development. Anticoagulation and rhythm/rate control strategies may protect against CI preventing or slowing its progression or conversion to dementia, particularly at the early stages when CI may still be a treatable condition. Importantly, AF and CI share many common risk factors. Thus, screening for these 2 conditions and searching for and managing modifiable risk factors and potentially reversible causes for both AF and CI remains an important step toward prevention or amelioration of the impact incurred by these 2 conditions.

Anticoagulant Therapy as a Tool for the Prevention of Cognitive Impairment Associated with Atrial Fibrillation

Atrial fibrillation (AF) is one of the most common cardiac arrhythmias in clinical practice and important additional risk factor for the development of cognitive impairment (CI) and dementia as it has been shown in recent studies. According to the Diagnostic and statistical manual of mental disorders latest revision CI refers to a decrease of one or more higher cortical functions that provide the processes of perception, storage, transformation and transmission of information compared to the premorbid level. The main hypothesis that explains the relationship between AF and dementia is the assumption that in the presence of this arrhythmia a brain substance is damaged due to microembolism and cerebral microbleeding. The high clinical significance of AF as well as CI served as a background for the development by European experts several consensus documents concerning the problem of the relationships between these conditions. In addition, they emphasize the role of anticoagulant therapy as a preventing tool for the development of stroke, which can be a factor in the CI progression in patients with AF, with particular priority to direct oral anticoagulants (DOACs). In randomized clinical trials, meta-analyses and systematic reviews have been shown that the use of DOACs, as compared to vitamin K antagonists, is a more rational strategy for preventing stroke associated with AF. Among the DOAC class, rivaroxaban is worth noticing as a drug that has a favorable efficacy profile for primary and secondary stroke prevention. Rivaroxaban distinguishing characteristics are a once daily administration as well as a calendar package which is practically important for patients with CI.

Risk of Seizures in Patients with Organophosphate Poisoning: A Nationwide Population-Based Study

Objective: Previous research has demonstrated that patients with a history of organophosphate poisoning tend to have a higher risk of neurological disorder. However, research on the rate of seizure development in patients after organophosphate poisoning is lacking. This study examined whether individuals with organophosphate poisoning have an increased risk of seizures through several years of follow-up. Patients and Methods: We conducted a retrospective study on a cohort of 45,060 individuals (9012 patients with a history of organophosphate poisoning and 36,048 controls) selected from the Taiwan National Health Insurance Research Database. The individuals were observed for a maximum of 12 years to determine the rate of new-onset seizure disorder. We selected a comparison cohort from the general population that was randomly frequency-matched by age, sex, and index year and further analyzed the risk of seizures using a Cox regression model adjusted for sex, age, and comorbidities. Results: During the study period, the risk of seizure development was 3.57 times greater in patients with organophosphate poisoning compared with individuals without, after adjustments for age, sex, and comorbidities. The absolute incidence of seizures was highest in individuals aged 20 to 34 years in both cohorts (adjusted hazard ratio = 13.0, 95% confidence interval = 5.40−31.4). A significantly higher seizure risk was also observed in patients with organophosphate poisoning and comorbidities other than cirrhosis. Conclusions: This nationwide retrospective cohort study demonstrates that seizure risk is significantly increased in patients with organophosphate poisoning compared with the general population.

Early temporal characteristics of elderly patient cognitive impairment in electronic health records

Background

The aging population has led to an increase in cognitive impairment (CI) resulting in significant costs to patients, their families, and society. A research endeavor on a large cohort to better understand the frequency and severity of CI is urgent to respond to the health needs of this population. However, little is known about temporal trends of patient health functions (i.e., activity of daily living [ADL]) and how these trends are associated with the onset of CI in elderly patients. Also, the use of a rich source of clinical free text in electronic health records (EHRs) to facilitate CI research has not been well explored. The aim of this study is to characterize and better understand early signals of elderly patient CI by examining temporal trends of patient ADL and analyzing topics of patient medical conditions in clinical free text using topic models.

Methods

The study cohort consists of physician-diagnosed CI patients (n = 1,435) and cognitively unimpaired (CU) patients (n = 1,435) matched by age and sex, selected from patients 65 years of age or older at the time of enrollment in the Mayo Clinic Biobank. A corpus analysis was performed to examine the basic statistics of event types and practice settings where the physician first diagnosed CI. We analyzed the distribution of ADL in three different age groups over time before the development of CI. Furthermore, we applied three different topic modeling approaches on clinical free text to examine how patients’ medical conditions change over time when they were close to CI diagnosis.

Results

The trajectories of ADL deterioration became steeper in CI patients than CU patients approximately 1 to 1.5 year(s) before the actual physician diagnosis of CI. The topic modeling showed that the topic terms were mostly correlated and captured the underlying semantics relevant to CI when approaching to CI diagnosis.

Conclusions

There exist notable differences in temporal trends of basic and instrumental ADL between CI and CU patients. The trajectories of certain individual ADL, such as bathing and responsibility of own medication, were closely associated with CI development. The topic terms obtained by topic modeling methods from clinical free text have a potential to show how CI patients’ conditions evolve and reveal overlooked conditions when they close to CI diagnosis.

Blinded Randomized Trial of Anticoagulation to Prevent Ischemic Stroke and Neurocognitive Impairment in Atrial Fibrillation (BRAIN-AF): Methods and Design

BACKGROUND

Compelling evidence showing a link between atrial fibrillation (AF) and cognitive decline and dementia is accumulating.

METHODS

Blinded Randomized Trial of Anticoagulation to Prevent Ischemic Stroke and Neurocognitive Impairment in Atrial Fibrillation (BRAIN-AF) is a prospective, multicentric, double-blind, randomized-controlled trial, recruiting patients with nonvalvular AF and a low risk of stroke. Patients with a high risk of bleeding will be excluded from the study. Participants will be randomized to receive either rivaroxaban (15 mg daily) or standard of care (placebo in patients without vascular disease or acetylsalicylic acid 100 mg daily in patients with vascular disease).

RESULTS

The primary outcome is the composite of stroke, transient ischemic attack, and cognitive decline (defined by a decrease in the Montreal Cognitive Assessment score ≥ 3 at any follow-up visit after baseline). Approximately 3250 patients will be enrolled in approximately 130 clinical sites until 609 adjudicated primary outcome events have occurred.

CONCLUSIONS

BRAIN-AF determines whether oral anticoagulation therapy with rivaroxaban compared with standard of care reduces the risk of stroke, transient ischemic attack, or cognitive decline in patients with nonvalvular AF and a low risk of stroke.

Effectiveness and safety of oral anticoagulants in older adults with non-valvular atrial fibrillation and heart failure

Direct oral anticoagulants (DOACs) are at least as efficacious and safe as warfarin among non-valvular atrial fibrillation (NVAF) patients; limited evidence is available regarding NVAF patients with heart failure (HF). US Medicare enrollees with NVAF and HF initiating DOACs (apixaban, rivaroxaban, dabigatran) or warfarin were selected. Propensity score matching and Cox models were used to estimate the risk of stroke/systemic embolism (SE), major bleeding (MB), and major adverse cardiac events (MACE) comparing DOACs versus warfarin and DOACs versus DOACs. We identified 10,570 apixaban-warfarin, 4,297 dabigatran-warfarin, 15,712 rivaroxaban-warfarin, 4,263 apixaban-dabigatran, 10,477 apixaban-rivaroxaban, and 4,297 dabigatran-rivaroxaban matched pairs. Compared to warfarin, apixaban had lower rates of stroke/SE (hazard ratio = 0.64, 95% confidence interval = 0.48-0.85), MB (hazard ratio = 0.66, 0.58-0.76), and MACE (hazard ratio = 0.73,0.67-0.79); dabigatran and rivaroxaban had lower rates of MACE (hazard ratio = 0.87,0.77-0.99; hazard ratio = 0.84, 0.79-0.89, respectively). Rivaroxaban had a lower stroke/SE rate (hazard ratio = 0.65, 0.52-0.81) and higher MB rate (hazard ratio = 1.18, 1.08-1.30) versus warfarin. Compared to dabigatran and rivaroxaban, apixaban had lower MB (hazard ratio = 0.71, 0.57-0.89; hazard ratio = 0.55, 0.49-0.63) and MACE rates (hazard ratio = 0.80, 0.69-0.93; hazard ratio = 0.86, 0.79-0.94), respectively. All DOACs had lower MACE rates versus warfarin; differences were observed in stroke/SE and MB. Our findings provide insights about OAC therapy among NVAF patients with HF.

Atrial Fibrillation and Risk of Dementia: Epidemiology, Mechanisms, and Effect of Anticoagulation

Atrial fibrillation (AF) is one of the cardiovascular risk factors for dementia. Several longitudinal studies have reported an association between AF and dementia independently of stroke history. Although the mechanisms underlying this association are not fully understood, proposed mechanisms include cerebral hypoperfusion, inflammation, genetic factors, cerebral microbleeds, and recurrent silent cerebral ischemia. Oral anticoagulation can be used to minimize risk of cognitive decline and dementia, given that brain insults can be caused by chronic microemboli or microbleeds. However, controversy on the effects of warfarin and direct oral anticoagulants on this risk exists. This article will address these aspects, with data on the studies already published and a critical view on this subject.

Default Mode Network Disruption in Stroke-Free Patients with Atrial Fibrillation

Background: Atrial fibrillation (AF) is a widely accepted risk for causing stroke. However, recent studies show AF as a risk factor for dementia, even without causing stroke. The mechanisms by which dementia develops in stroke-free patients with AF are still poorly understood and the association of AF with abnormal function of brain networks activities, such as the default mode network (DMN), has not been previously studied. We aimed to determine whether, in the absence of stroke and dementia, patients with AF have abnormal resting-state brain networks compared to controls without AF. Methods: Twenty-one stroke-free patients with AF and 21 age- and sex-matched controls without AF underwent brain functional magnetic resonance imaging acquired at a 3.0 Tesla scanner. During the exam, the subjects were instructed to lie still with eyes closed. At first-level analysis, connectivity of the DMN was obtained for all subjects. Second-level analysis compared the DMN connectivity between AF patients and controls with a general linear model (two-sample t test, p < 0.05, False Discovery Rate corrected, minimum of 50 contiguous voxels). Results: Patients with AF compared with controls showed decreased connectivity in regions of the DMN including the frontal lobe (left medial frontal gyrus, left superior frontal gyrus and anterior cingulate), left angular gyrus, and bilateral precuneus. Conclusions: Stroke-free patients with AF have evidence of abnormal DMN connectivity. This study adds evidence to the occurrence of cerebral dysfunction in patients with AF.

Alteration of cerebrovascular haemodynamic patterns due to atrial fibrillation: an in silico investigation

There has recently been growing evidence that atrial fibrillation (AF), the most common cardiac arrhythmia, is independently associated with the risk of dementia. This represents a very recent frontier with high social impact for the number of individuals involved and for the expected increase in AF incidence in the next 40 years. Although a number of potential haemodynamic processes, such as microembolisms, altered cerebral blood flow, hypoperfusion and microbleeds, arise as connecting links between the two pathologies, the causal mechanisms are far from clear. An in silico approach is proposed that combines in sequence two lumped-parameter schemes, for the cardiovascular system and the cerebral circulation. The systemic arterial pressure is obtained from the cardiovascular system and used as the input for the cerebral circulation, with the aim of studying the role of AF on the cerebral haemodynamics with respect to normal sinus rhythm (NSR), over a 5000 beat recording. In particular, the alteration of the haemodynamic (pressure and flow rate) patterns in the microcirculation during AF is analysed by means of different statistical tools, from correlation coefficients to autocorrelation functions, crossing times, extreme values analysis and multivariate linear regression models. A remarkable signal alteration, such as a reduction in signal correlation (NSR, about 3 s; AF, less than 1 s) and increased probability (up to three to four times higher in AF than in NSR) of extreme value events, emerges for the peripheral brain circulation. The described scenario offers a number of plausible cause-effect mechanisms that might explain the occurrence of critical events and the haemodynamic links relating to AF and dementia.

A Risk Factor Analysis of Cognitive Impairment in Elderly Patients with Chronic Diseases in a Chinese Population

Background

This study analyzed the risk factors of cognitive impairment (CI) in elderly patients with chronic diseases.

Material/Methods

In total of 385 elderly patients with chronic diseases were selected and assigned into CI and normal groups. The activities of daily living (ADL), global deterioration scale (GDS), Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment Scale (MoCA), patient-generated subjective global assessment (PG-SGA), and mini nutritional assessment (MNA) were performed to analyze the differences between the 2 groups. Logistic regression analysis was conducted for risk factors of CI in elderly patients with chronic diseases.

Results

There were differences in age, education level, type 2 diabetes mellitus, multifocal cerebral infarction, hearing, and eyesight between CI and normal groups. Patients in the CI group showed more CD4⁺ cells, more admission times, and higher GDS scores than the normal group. Also, MMSE and MoCA scores revealed differences in total score, directive force, attention and calculating ability, language, delayed memory, reading comprehension, writing, and visual-spatial ability between the 2 groups. The number of B and CD8⁺ cells, ADL, and MNA scores were protective factors, while cerebral infarction history, number of CD4+ cells, admission times, GDS score, and age were risk factors of CI in elderly patients with chronic diseases.

Conclusions

Our study provides evidence that cerebral infarction history, number of CD4+ cells, admission times, GDS score, and age are risk factors of CI in elderly patients with chronic diseases.

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.

Dementia correlates with anticoagulation underuse in older patients with atrial fibrillation

OBJECTIVES

Stroke prevention in older atrial fibrillation (AF) patients remains a challenge. This study aimed to investigate whether a dementia diagnosis is an independent correlate of lower prescription rate of oral anticoagulant treatment (OAT) in a sample of older AF patients.

METHODS

Cross-sectional retrospective study. Consecutive older community-dwelling AF patients referred for a comprehensive geriatric assessment, were considered. Evaluation of physical, social and mental health, and administration of the Cumulative Illness Rating Scale (CIRS) and Barthel Index were performed. Dementia cases were ascertained by consensus of 2 experienced geriatricians. Dementia severity was assessed using the Clinical Dementia Rating scale (CDR).

RESULTS

316 AF patients (ages 74.7±7.0years, 55.7% women) with high stroke risk (77.5% had a CHA₂DS₂VASC score ≥3), low bleeding and falling risk, and no neuropsychiatric/behavioral symptoms, were included. 60.1% were prescribed with OAT. Among patients with dementia (n=86, 27.2%), 22.0% received inadequate antithrombotic prophylaxis (i.e. antiplatelet) and 38.5% no treatment. Proportion of those receiving inadequate or no prophylaxis increased at increasing CDR score. By multiple regression models, either dementia (yes vs no), OR=1.33, 95%CI=1.11-1.46, p<0.001, and dementia severity (CDR>1), OR=2.38, 95%CI=2.19-2.60, p<0.001, were associated with lack of OAT prescription independently of age, paroxysmal AF, and comorbidity burden.

CONCLUSIONS

Dementia might be associated with underuse of OAT in older AF patients even in the absence of established contraindications. Future studies are needed to assess the real dimension of the problem and clinician's barriers to prescribing OAT in demented patients.

Serum brain-derived neurotrophic factor and risk of atrial fibrillation

Brain-derived neurotrophic factor (BDNF) is expressed by endothelial cells and can affect cardiovascular function. We examined if serum BDNF was associated with risk of incident atrial fibrillation (AF) in the Framingham Heart Study.

METHODS

We studied individuals without an AF diagnosis at baseline from the Framingham original and offspring cohorts. We used age- and sex-adjusted, and multivariable-adjusted Cox proportional hazards regression models to examine the association of serum BDNF concentrations with 10-year risk of incident AF.

RESULTS

We studied 3,457 participants (mean age 65±11years, 58% women). During follow-up, 395 participants developed AF. In unadjusted analysis, higher mean serum BDNF concentration was associated with lower incidence of AF (hazard ratio 0.89 per SD, 95% CI 0.80-0.99). In multivariable-adjusted analyses, serum BDNF concentration was not significantly associated with incident AF (hazard ratio 0.98 per SD, 95% CI 0.88-1.09). Compared with the lowest quartile, BDNF levels in the other quartiles were not associated with risk of AF in multivariable-adjusted analyses. No interactions between sex or age with serum BDNF concentrations and risk of AF were found.

CONCLUSIONS

In our prospective, community-based sample, we did not find a statistically significant association of serum BDNF levels with risk of incident AF.

Usefulness of the CHADS2 Score for Determining Risk of Seizure in Patients With Atrial Fibrillation

Atrial fibrillation (AF) secondary to seizure has been described in case reports, but the association between AF and risk of seizure has never been evaluated in longitudinal studies. The objectives of this study were to investigate the role of AF on the risk of development of seizure and the usefulness of CHADS₂ score for predicting the risk of seizure. Our analyses were conducted using information from a random sample of 1 million subjects enrolled in Taiwan National Health Insurance Research Database. A total of 11,552 subjects aged ≥18 years, comprising 5,776 subjects diagnosed with AF during the study period and 5,776 age and sex-matched subjects without AF were enrolled in our study. During the mean follow-up of 6.7 ± 3.3 years, seizure events occurred in 235 patients. In comparison, the AF group had a higher incidence rate of seizure occurrence (4.17 vs 1.90 per 1,000 person-years). Cox proportional hazard regression model analysis showed that development of AF was independently associated with a higher risk of developing future seizure (adjusted HR 2.30; 95% confidence interval 1.73 to 3.05). In multivariate Cox regression analysis adjusted for potentially confounding variables, a higher CHADS₂ score was associated with a higher risk of seizure in a dose-dependent manner. AF may cause an ischemic stroke that subsequently leads to seizure, and present study further demonstrates that AF patients are associated with higher rate of subsequent seizure, even after adjusting for stroke. The CHADS₂ score was found to be a useful scheme for predicting the risk of seizure occurrence.

Dementia and Traffic Accidents: A Danish Register-Based Cohort Study

Background

As a consequence of a rapid growth of an ageing population, more people with dementia are expected on the roads. Little is known about whether these people are at increased risk of road traffic-related accidents.

Objective

Our study aims to investigate the risk of road traffic-related accidents for people aged 65 years or older with a diagnosis of dementia in Denmark.

Methods

We will conduct a nationwide population-based cohort study consisting of Danish people aged 65 or older living in Denmark as of January 1, 2008. The cohort is followed for 7 years (2008-2014). Individual’s personal data are available in Danish registers and can be linked using a unique personal identification number. A person is identified with dementia if the person meets at least one of the following criteria: (1) a diagnosis of the disease in the Danish National Patient Register or in the Danish Psychiatric Central Research Register, and/or (2) at least one dementia diagnosis-related drug prescription registration in the Danish National Prescription Registry. Police-, hospital-, and emergency room-reported road traffic-related accidents occurred within the study follow-up are defined as the study outcome. Cox proportional hazard regression models are used for the main analysis.

Results

Our study protocol has 3 phases including data collection, data analysis, and reporting. The first phase of register-based data collection of 853,228 individual’s personal information was completed in August, 2016. The next phase is data analysis, which is expected to be finished before December 2016, and thereafter writing publications based on the findings. The study started in January 2016 and will end in December 2018.

Discussion

This study covers the entire elderly population of Denmark, and thereby will avoid selection bias due to nonparticipation and loss to follow-up. Furthermore, this ensures that the study results are reliable and generalizable. However, underreporting of traffic-related accidents may occur, which will limit estimation of absolute risks.

Atrial fibrillation management in older heart failure patients: a complex clinical problem

BACKGROUND

Atrial fibrillation (AF) and heart failure (HF), two problems of growing prevalence as a consequence of the ageing population, are associated with high morbidity, mortality, and healthcare costs. AF and HF also share common risk factors and pathophysiologic processes such as hypertension, diabetes mellitus, ischemic heart disease, and valvular heart disease often occur together. Although elderly patients with both HF and AF are affected by worse symptoms and poorer prognosis, there is a paucity of data on appropriate management of these patients.

METHODS

PubMed was searched for studies on AF and older patients using the terms atrial fibrillation, elderly, heart failure, cognitive impairment, frailty, stroke, and anticoagulants.

RESULTS

The clinical picture of HF patients with AF is complex and heterogeneous with a higher prevalence of frailty, cognitive impairment, and disability. Because of the association of mental and physical impairment to non-administration of oral anticoagulants (OACs), screening for these simple variables in clinical practice may allow better strategies for intervention in this high-risk population. Since novel direct OACs (NOACs) have a more favorable risk-benefit profile, they may be preferable to vitamin K antagonists (VKAs) in many frail elderly patients, especially those at higher risk of falls. Moreover, NOACs are simple to administer and monitor and may be associated with better adherence and safety in patients with cognitive deficits and mobility impairments.

CONCLUSIONS

Large multicenter longitudinal studies are needed to examine the effects of VKAs and NOACs on long-term cognitive function and frailty; future studies should include geriatric conditions.

Risk Factors and Cognitive Relevance of Cortical Cerebral Microinfarcts in Patients With Ischemic Stroke or Transient Ischemic Attack

BACKGROUND AND PURPOSE

It was recently demonstrated that cerebral microinfarcts (CMIs) can be detected in vivo using 3.0 tesla (T) magnetic resonance imaging. We investigated the prevalence, risk factors, and the longitudinal cognitive consequence of cortical CMIs on 3.0T magnetic resonance imaging, in patients with ischemic stroke or transient ischemic attack.

METHODS

A total of 231 patients undergoing 3.0T magnetic resonance imaging were included. Montreal Cognitive Assessment was used to evaluate global cognitive functions and cognitive domains (memory, language, and attention visuospatial and executive functions). Cognitive changes were represented by the difference in Montreal Cognitive Assessment score between baseline and 28-month after stroke/transient ischemic attack. The cross-sectional and longitudinal associations between cortical CMIs and cognitive functions were explored using ANCOVA and regression models.

RESULTS

Cortical CMIs were observed in 34 patients (14.7%), including 13 patients with acute (hyperintense on diffusion-weighted imaging) and 21 with chronic CMIs (isointense on diffusion-weighted imaging). Atrial fibrillation was a risk factor for all cortical CMIs (odds ratio, 4.8; 95% confidence interval, 1.5-14.9; P=0.007). Confluent white matter hyperintensities was associated with chronic CMIs (odds ratio, 2.8; 95% confidence interval, 1.0-7.8; P=0.047). The presence of cortical CMIs at baseline was associated with worse visuospatial functions at baseline and decline over 28-month follow-up (β=0.5; 95% confidence interval, 0.1-1.0; P=0.008, adjusting for brain atrophy, white matter hyperintensities, lacunes, and microbleeds).

CONCLUSIONS

Cortical CMIs are a common finding in patients with stroke/transient ischemic attack. Associations between CMI with atrial fibrillation and white matter hyperintensities suggest that these lesions have a heterogeneous cause, involving microembolism and cerebral small vessel disease. CMI seemed to preferentially impact visuospatial functions as assessed by a cognitive screening test.

Identification of sub-groups in acutely ill elderly patients with delirium: a cluster analysis

BACKGROUND

Delirium is a serious neuropsychiatric syndrome affecting mainly elderly participants with acute medical diseases. The pathophysiology of delirium remains poorly understood as it involves complex dynamic interactions between a diversity of risk factors. Exploring how etiological factors interact with each other can clarify the pathophysiological mechanisms and facilitate the early identification of this syndrome. The aim of this study was to explore how different risk factors co-occur in medically ill elderly patients with delirium with cluster analysis and identify clinically meaningful sub-groups in this population.

METHODS

A cross-sectional study was developed. Ninety-nine elderly inpatients admitted to acute medical wards diagnosed with delirium during hospitalization were selected. For each patient sociodemographic characteristics, acute and chronic medical conditions, laboratory parameters, and current medication were collected.

RESULTS

The cluster analysis extracted three distinct subgroups of participants with delirium. Patients in cluster 1 (n = 28) had higher rates of medication with anticholinergic proprieties. Cluster 2 (n = 29) included participants with cardiac and pulmonary comorbidities associated with both chronic and acute reduction of blood flow and/or oxygenation to the brain. Cluster 3 (n = 42 patients) comprised patients with simultaneous deregulation of different organs/systems, such as electrolytic disturbances, metabolic disturbances, and acute renal failure. Known predisposing factors of delirium, such as age and pre-existing dementia, were similar between groups.

CONCLUSIONS

The results reveal different patterns of clinical characteristics in elderly patients with delirium. This is relevant to clinical care of acute medically ill patients and suggests that different pathways are implicated in delirium pathophysiology.

Risk of dementia and death in patients with atrial fibrillation: A competing risk analysis of a population-based cohort

BACKGROUND

Previous studies have stated that atrial fibrillation (AF) is associated with a higher risk of dementia. However, none have examined the competition between death and incident dementia in patients with AF. We evaluated the risk of incident dementia in patients with AF in comparison to people without this arrhythmia, considering of the competing risk of death.

METHODS

AF and non-AF cohorts were identified using the large administrative database of the Lombardy Region and followed for ten years. Patients with incident dementia were identified if they had an ICD 9 code referring to dementia at hospital discharge or a prescription for any anti-dementia drug. The association of AF with dementia or death was assessed with the multivariable Cox proportional-regression model, sensitivity analysis with a 1:1 propensity score matching and competing-risk analysis.

RESULTS

In 2003 a total of 27,431 patients were hospitalized for AF in the Lombardy Region, while the cohort of non-AF counted 1,600,200 people. AF was associated with a higher risk of dementia (17%) and death (51%) at multivariable Cox analysis. These results were confirmed by the model fitted after propensity score matching. However, competing risk analysis found the association between AF and incident dementia was no longer significant (HR 0.99; 95% CI 0.94-1.04).

CONCLUSIONS

In this real-world population the association between AF and dementia was no longer statistically significant when death was considered a competing risk.

Antithrombotic treatment in elderly patients with atrial fibrillation: a practical approach

BACKGROUND

Atrial fibrillation (AF) in the elderly is a complex condition. It has a direct impact on the underuse of antithrombotic therapy reported in this population.

DISCUSSION

All patients aged ≥75 years with AF have an individual yearly risk of stroke >4 %. However, the risk of hemorrhage is also increased. Moreover, in this population it is common the presence of other comorbidities, cognitive disorders, risk of falls and polymedication. This may lead to an underuse of anticoagulant therapy. Direct oral anticoagulants (DOACs) are at least as effective as conventional therapy, but with lesser risk of intracranial hemorrhage. The simplification of treatment with these drugs may be an advantage in patients with cognitive impairment. The great majority of elderly patients with AF should receive anticoagulant therapy, unless an unequivocal contraindication. DOACs may be the drugs of choice in many elderly patients with AF. In this manuscript, the available evidence about the management of anticoagulation in elderly patients with AF is reviewed. In addition, specific practical recommendations about different controversial issues (i.e. patients with anemia, thrombocytopenia, risk of gastrointestinal bleeding, renal dysfunction, cognitive impairment, risk of falls, polymedication, frailty, etc.) are provided.

Relationship of Age With Stroke and Death in Anticoagulated Patients With Nonvalvular Atrial Fibrillation

Background and Purpose—

The prevalence of atrial fibrillation increases with age, but age-specific data on the incidence of stroke and death in anticoagulated patients with atrial fibrillation are more limited, particularly with regard to comparisons of relative risks of clinical outcomes between the different age strata in relation to quality of anticoagulation control among warfarin users.

Methods—

We investigated the incidence of adverse outcomes between tertiles of age groups (age, <67 [n=722]; age, 67–74 [n=747]; and age, ≥75 [n=824]) in 2293 patients with atrial fibrillation participating in warfarin arm in the AMADEUS (Evaluating the Use of SR34006 Compared to Warfarin or Acenocoumarol in Patients With Atrial Fibrillation) trial. The average time in therapeutic range was calculated as a measure of anticoagulation control and related to clinical outcomes.

Results—

Absolute rates for stroke/systemic embolism (SSE), cardiovascular death, or any clinically relevant bleeding increased with increasing age strata. The combined end point of cardiovascular death and SSE was the highest in the top tertile (adjusted hazard ratio, 2.63; 95% confidence interval, 1.23–5.63) compared with the middle and lowest tertiles ( P for trend=0.01). For bleeding, there was no significant difference in relative risks between the age strata ( P for trend=0.55 in the warfarin group and in the warfarin group with time in therapeutic range ≥60%, P for trend=0.60). The quality of anticoagulation control (time in therapeutic range) significantly correlated with any clinically relevant bleeding ( r =−0.91; P <0.001) and cardiovascular death/SSE rates ( r =−0.76; P =0.01).

Conclusions—

Elderly patients with atrial fibrillation have higher absolute risks of cardiovascular death, SSE, and bleeding, but relative risks of clinically relevant bleeding are not significantly different with increasing age strata. A significant inverse relationship between time in therapeutic range and bleeding and cardiovascular death/SSE emphasizes the importance of good quality anticoagulation control.

Stroke prevention in the elderly atrial fibrillation patient with comorbid conditions: focus on non-vitamin K antagonist oral anticoagulants

Stroke prevention in elderly atrial fibrillation patients remains a challenge. There is a high risk of stroke and systemic thromboembolism but also a high risk of bleeding if anticoagulants are prescribed. The elderly have increased chronic kidney disease, coronary artery disease, polypharmacy, and overall frailty. For all these reasons, anticoagulant use is underutilized in the elderly. In this manuscript, the benefits of non-vitamin K antagonist oral anticoagulants compared with warfarin in the elderly patient population with multiple comorbid conditions are reviewed.

Challenges and misconceptions in the aetiology and management of atrial fibrillation-related strokes

Strokes, whether ischaemic or haemorrhagic, are the most feared complications of atrial fibrillation (AF) and its treatment. Vitamin K antagonists have been the mainstay of stroke prevention. Recently, direct oral anticoagulants have been introduced. The advantages and disadvantages of these treatment strategies have been extensively discussed. In this narrative review, we discuss dilemmas faced by primary care clinicians in the context of stroke and transient ischaemic attack (TIA) in patients with AF. We discuss the classification of stroke, the different types of stroke seen with AF, the prognosis of AF-related strokes, the early management after AF-related stroke or TIA and the therapeutic options after anticoagulant-associated intracerebral haemorrhage. Most importantly, we aim to dispel common misconceptions on the part of non-stroke specialists that can lead to suboptimal stroke prevention and management.

Risk and prediction of dementia in patients with atrial fibrillation--a nationwide population-based cohort study

BACKGROUND

Atrial fibrillation (AF) is associated with an increased risk of cognitive impairment and functional decline, and may contribute to development of dementia.

OBJECTIVES

Data from a nationwide large-scale population-based cohort study are lacking. Besides, how best to predict the occurrence of incident dementia among AF subjects remains uncertain.

METHODS

A total of 332,665 AF subjects without dementia were identified as the study group from the "National Health Insurance Research Database" in Taiwan. For each study patient, one age- and sex-matched subject without AF and dementia was selected as the control group. The study end point was occurrence of dementia, and the usefulness of CHADS2 and CHA2DS2-VASc scores in predicting dementia was analyzed.

RESULTS

During the follow-up, 29,012 AF patients experienced dementia with an annual incidence of 2.12%, higher than non-AF subjects (1.50%). Patients with AF possessed a higher risk of dementia with a hazard ratio (HR) of 1.420 after adjustments for age, gender, baseline differences and medication use. Among AF patients, the CHADS2 and CHA2DS2-VASc scores were significant predictors of dementia with an adjusted HR of 1.520 and 1.497 per 1 increment of the CHADS2 and CHA2DS2-VASc scores, respectively. The c-index for CHA2DS2-VASc in predicting dementia (0.611, 95% confidence interval [CI]=0.608-0.614) was significantly higher than the CHADS2 score (0.589, 95% CI=0.586-0.592) (DeLong test p<0.001).

CONCLUSIONS

In this nationwide cohort study, AF was independently associated with a higher risk of dementia. The CHA2DS2-VASc score can be used to estimate the risk of dementia in AF patients.

Brain and kidney, victims of atrial microembolism in elderly hospitalized patients? Data from the REPOSI study

BACKGROUND

It is well known that atrial fibrillation (AF) and chronic kidney disease (CKD) are associated with a higher risk of stroke, and new evidence links AF to cognitive impairment, independently from an overt stroke (CI). Our aim was to investigate, assuming an underlying role of atrial microembolism, the impact of CI and CKD in elderly hospitalized patients with AF.

METHODS

We retrospectively analyzed the data collected on elderly patients in 66 Italian hospitals, in the frame of the REPOSI project. We analyzed the clinical characteristics of patients with AF and different degrees of CI. Multivariate logistic analysis was used to explore the relationship between variables and mortality.

RESULTS

Among the 1384 patients enrolled, 321 had AF. Patients with AF were older, had worse CI and disability and higher rates of stroke, hypertension, heart failure, and CKD, and less than 50% were on anticoagulant therapy. Among patients with AF, those with worse CI and those with lower estimated glomerular filtration rate (eGFR) had a higher mortality risk (odds ratio 1.13, p=0.006). Higher disability levels, older age, higher systolic blood pressure, and higher eGFR were related to lower probability of oral anticoagulant prescription. Lower mortality rates were found in patients on oral anticoagulant therapy.

CONCLUSIONS

Elderly hospitalized patients with AF are more likely affected by CI and CKD, two conditions that expose them to a higher mortality risk. Oral anticoagulant therapy, still underused and not optimally enforced, may afford protection from thromboembolic episodes that probably concur to the high mortality.

Atrial fibrillation: A major risk factor for cognitive decline

Atrial fibrillation is a common disease of the elderly, conferring considerable morbidity and mortality related to cardiovascular effects and thromboembolic risks. Anticoagulation, antiarrhythmic medications, and rate control are the cornerstone of contemporary management, whereas ablation and evolving surgical techniques continue to play important secondary roles. Growing evidence shows that atrial fibrillation is also a risk factor for significant cognitive decline through a multitude of pathways, further contributing to morbidity and mortality. At the same time, cognitive decline associated with cryptogenic strokes may be the first clue to previously undiagnosed atrial fibrillation. These overlapping associations support the concept of cognitive screening and rhythm monitoring in these populations. New research suggests modulating effects of currently accepted treatments for atrial fibrillation on cognition; however, there remains the need for large multicenter studies to examine the effects of novel oral anticoagulants, rhythm and rate control, and left atrial appendage occlusion on long-term cognitive function.

Atrial fibrillation exacerbates cognitive dysfunction and cerebral perfusion in heart failure

BACKGROUND

Heart failure (HF) increases risk for cognitive impairment in part due to the negative effects of cardiac dysfunction on cerebral perfusion. Atrial fibrillation (AF), an independent risk factor for cognitive impairment, often accompanies HF and is associated with lower systemic perfusion. However, no study has examined the associations among AF, cognitive function, and cerebral perfusion in patients with HF.

METHODS

A total of 187 HF patients completed neuropsychological testing and underwent transcranial Doppler ultrasonography. Cerebral blood flow velocity of the middle cerebral artery (CBF-V) operationalized cerebral perfusion. A medical chart review ascertained AF.

RESULTS

History of AF was found in 32.1% of HF patients. HF patients with AF exhibited worse global cognition, memory, and CBF-V relative to patients without AF. These effects remained after HF severity and other demographic and medical factors were taken into account. Partial correlations controlling for possible confounds showed decreased CBF-V predicted worse cognition in multiple domains in the overall sample (r = 0.13 to 0.15, P < 0.05) and in the subgroup of HF patients with AF (r = 0.26 to r = 0.28, P < 0.05), but not among HF patients without AF.

CONCLUSIONS

AF exacerbates cognitive deficits in HF, possibly through its association with decreased cerebral perfusion. Longitudinal studies are needed to determine whether AF accelerates cognitive decline in HF and whether medical (e.g., ablation) and lifestyle interventions (e.g., exercise programs) that target cerebral perfusion improve cognitive outcomes in patients with HF and AF.

Global epidemiology of atrial fibrillation

Atrial fibrillation (AF) is a major public health burden worldwide, and its prevalence is set to increase owing to widespread population ageing, especially in rapidly developing countries such as Brazil, China, India, and Indonesia. Despite the availability of epidemiological data on the prevalence of AF in North America and Western Europe, corresponding data are limited in Africa, Asia, and South America. Moreover, other observations suggest that the prevalence of AF might be underestimated-not only in low-income and middle-income countries, but also in their high-income counterparts. Future studies are required to provide precise estimations of the global AF burden, identify important risk factors in various regions worldwide, and take into consideration regional and ethnic variations in AF. Furthermore, in response to the increasing prevalence of AF, additional resources will need to be allocated globally for prevention and treatment of AF and its associated complications. In this Review, we discuss the available data on the global prevalence, risk factors, management, financial costs, and clinical burden of AF, and highlight the current worldwide inadequacy of its treatment.

Preserving Cognitive Function in Patients with Atrial Fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide and is associated with significant morbidity and mortality. Its prevalence increases with increasing age, and is one of the leading causes of thromboembolism, including ischemic stroke. The prevalence of cognitive dysfunction also increases with increasing age. Although several studies have shown a strong correlation between AF and cognitive dysfunction in patients with and without overt stroke, a direct causative link has yet to be established. Rhythm vs rate control and anticoagulation regimens have been extensively investigated, particularly with the introduction of the novel anticoagulants. With catheter ablation becoming more prevalent for the management of AF and the ongoing development of various new energy sources and catheters, an additional thromboembolism risk is introduced. As cognitive dysfunction decreases the patient's ability to self-care and manage a complex disease such as AF, this increases the burden to our healthcare system. Therefore as the prevalence of AF increases in the general population, it becomes more imperative that we strive to optimize our methods to preserve cognitive function. This review gives an overview of the current evidence behind the association of AF with cognitive dysfunction, and discusses the most up-to-date medical and procedural treatment strategies available for decreasing thromboembolism associated with AF and its treatment, which may lead to preserving cognitive function.