Silent Atrial Fibrillation and Cryptogenic Strokes

A new suspected cause of cryptic strokes is “silent atrial fibrillation.” Pacemakers and other implanted devices allow continuous recording of cardiac rhythm for months or years. They have discovered that short periods of atrial fibrillation lasting minutes or hours are frequent and usually are asymptomatic. A meta-analysis of 50 studies involving more than 10,000 patients with a recent stroke found that 7.7% had new atrial fibrillation on their admitting electrocardiogram. In 3 weeks during and after hospitalization, another 16.9% were diagnosed. A total of 23.7% of these stroke patients had silent atrial fibrillation; that is, atrial fibrillation diagnosed after hospital admission. Silent atrial fibrillation is also frequent in patients with pacemakers who do not have a recent stroke. In a pooled analysis of 3 studies involving more than 10,000 patients monitored for 24 months, 43% had at least 1 day with atrial fibrillation lasting more than 5 minutes. Ten percent had atrial fibrillation lasting at least 12 hours. Despite the frequency of silent atrial fibrillation in these patients with multiple risk factors for stroke, the annual incidence of stroke was only 0.23%. When silent atrial fibrillation is detected in patients with recent cryptogenic stroke, anticoagulation is indicated. In patients without stroke, silent atrial fibrillation should lead to further monitoring for clinical atrial fibrillation rather than immediate anticoagulation, as some have advocated.     

Mechanisms and Clinical Manifestations of Cognitive Decline in Atrial Fibrillation Patients: Potential Implications for Preventing Dementia

Atrial fibrillation (AF) patients face an approximate 1.5-fold increased risk of cognitive decline compared with the general population. Among poststroke AF patients, the risk of cognitive decline is even higher with an estimated threefold increase. This article provides a narrative review on the current evidence and highlights gaps in knowledge and areas for future research. Although earlier studies hypothesized that the association between AF and cognitive decline is mainly a consequence of previous ischemic strokes, more recent evidence also suggests such an association in AF patients without a history of clinical stroke. Because AF and cognitive decline mainly occur among elderly individuals, it is not surprising that both entities share multiple risk factors. In addition to clinically overt ischemic strokes, silent brain infarcts and other brain injury are likely mechanisms for the increased risk of cognitive decline among AF patients. Oral anticoagulation for stroke prevention in AF patients with additional stroke risk factors is one of the only proven therapies to prevent brain injury. Whether a broader use of oral anticoagulation, or more intense anticoagulation in some patients are beneficial in this context needs to be addressed in future studies. Although direct studies are lacking, it is reasonable to recommend optimal treatment of comorbidities and risk factors for the prevention of cognitive decline and dementia.     

Atrial Fibrillation and Cognitive Function: JACC Review Topic of the Week

Numerous vascular risk factors and vascular diseases contribute to cognitive impairment and dementia. Many studies and registries show an association of atrial fibrillation (AF) with cognitive impairment, cognitive decline, and dementia. This is true for vascular dementia and Alzheimer's disease. The assumed multifactorial mechanisms include ischemic stroke, both apparent and silent, cerebral microinfarcts, cerebral hemorrhage, and reduced cerebral blood flow. A number of retrospective observational and prospective studies support that anticoagulation in patients with AF may reduce the risk of cognitive decline and dementia. This holds for both vitamin K antagonists (e.g., warfarin) and direct oral anticoagulants. However, it still remains unproven if anticoagulation reduces cognitive decline and dementia in AF patients based on randomized trials.     

心房颤动和认知功能下降的关系研究

心房颤动(房颤)是老年人常见的心律失常,并随着年龄增长发病率及病死率增高.众多的血管危险因素和血管疾病导致认知功能障碍和痴呆,而年龄亦是认知功能障碍的最主要因素.房颤和认知功能障碍相关的可能机制有:共同危险因素及共患病、缺血性卒中(有症状或无症状)和房颤的促炎状态等.房颤患者窦律的恢复和抗凝治疗有可能降低认知功能障碍的...     

无症状卒中研究进展

随着影像学技术的发展，尤其是磁共振弥散加权成像的应用，可以很容易地检测到无症状卒中病灶。无症状卒中的患病率和发病率均高于有症状卒中，年龄、高血压、心房颤动等是其公认的危险因素。尽管按照定义无症状卒中缺乏临床卒中样症状，但仔细检查仍常有轻微的躯体和认知功能障碍。此外，无症状卒中还与随后的有症状卒中、认知功能减退以及痴呆的发生有关。因此，临床医生需予以重视，积极控制其高危因素和改善其预后。     

无症状卒中研究进展

随着影像学技术的发展,尤其是磁共振弥散加权成像的应用,可以很容易地检测到无症状卒中病灶.无症状卒中的患病率和发病率均高于有症状卒中,年龄、高血压、心房颤动等是其公认的危险因素.尽管按照定义无症状卒中缺乏临床卒中样症状,但仔细检查仍常有轻微的躯体和认知功能障碍.此外,无症状卒中还与随后的有症状卒中、认知功能减退以及痴呆的发生有关.因此,临床医生需予以重视,积极控制其高危因素和改善其预后.     

Antikoagulation bei Vorhofflimmern

Atrial fibrillation is associated with a relevant risk for ischemic stroke: Observational studies suggest that one in four to five strokes is due to atrial fibrillation. Depending on the risk profile of an individual patient, the yearly risk for a stroke is between 2% and 14%. Continuous oral anticoagulation is indicated if atrial fibrillation is accompanied by at least one additional risk factor for thromboembolic complications. This recommendation is supported by several large randomized trials. Due to their low therapeutic range, vitamin K antagonists (phenprocoumon, warfarin, and others), the most commonly used oral anticoagulants, require regular anticoagulation monitoring. If well-controlled (international normalized ratio 2-3, in elderly patients preferably 2-2.5), oral anticoagulation prevents more than half of ischemic strokes related to atrial fibrillation, while bleeding complications are rare. In the follow-up of low risk patients (CHADS2-Score 0), oral anticoagulation becomes necessary when risk factors for thromboembolic complications develop. If a stroke occurs during oral anticoagulation and an INR>2 in a patient with atrial fibrillation, other causes than thromboembolic events should be considered. New anticoagulants--especially direct thrombin antagonists--are currently evaluated in clinical trials and may in the future facilitate anticoagulation in patients with atrial fibrillation.     

Randomized Trials of Rate vs. Rhythm Control for Atrial Fibrillation

Recent randomized trials have not demonstrated mortality or stroke risk reduction benefits from a rhythm-control compared to rate-control strategy in the treatment of atrial fibrillation. These studies reinforce the need for continued anticoagulation in both strategies for patients with atrial fibrillation and risk factors for stroke. Although rate control can be rationalized as a first line approach, rhythm control strategies may be justified for patients who are younger, who remain symptomatic or functionally impaired, or who have a first episode of atrial fibrillation.     

Anticoagulant-related bleeding in older persons with atrial fibrillation: physicians' fears often unfounded

BACKGROUND: Many studies have documented the underuse of anticoagulant (ie, warfarin sodium) therapy as stroke prophylaxis in older persons with atrial fibrillation. Failure to prescribe anticoagulant agents to these patients is often due to physicians' perceiving the risk of major bleeding as unacceptably high because of the presence of such clinical risk factors as hypertension, falls, a history of gastrointestinal tract bleeding, and lack of assurance about compliance. OBJECTIVES: To critically appraise whether the presence of additional clinical factors that increase the risk of bleeding affects the chance of anticoagulant-related hemorrhage, and to develop an approach to the use of anticoagulant agents in older patients with atrial fibrillation who have any of these factors. METHODS: Systematic MEDLINE literature search from January 1966 to March 2002. RESULTS: Many of the factors that are purported to be barriers to anticoagulant therapy in older persons with atrial fibrillation probably should not influence the choice of stroke prophylaxis in these patients. These include previous episodes of upper gastrointestinal tract bleeding, predisposition to falling, and old age in itself. For some other factors, such as alcoholism, participation in activities that predispose to trauma, the presence of a bleeding diathesis or thrombocytopenia, and noncompliance with monitoring, there is little or conflicting evidence about their effect on anticoagulant-related bleeding. However, they should be considered in the clinical decision-making process. CONCLUSIONS: For many older patients with atrial fibrillation, physicians' fears of the risk of bleeding in association with anticoagulant therapy are often exaggerated and unfounded. Therefore, the salient issue in selecting older patients with atrial fibrillation for anticoagulation is accurately estimating their stroke risk, with bleeding risk during anticoagulation being a lesser issue, relevant to only a few patients.     

Anticoagulation in Patients with Acute Ischemic Stroke and Atrial Fibrillation—a Balance of Risks and Benefits

OBJECTIVES: We reviewed the current literature regarding anticoagulation in patients presenting with acute ischemic stroke and atrial fibrillation. METHODS: A systematic literature search was performed using PUBMED. All relevant articles including meta-analysis, original case studies and cross-references from relevant articles were included in this review. RESULTS: Atrial fibrillation is a thrombogenic state and predisposes to acute embolic strokes. Most studies do not show any mortality or morbidity benefit of anticoagulation with unfractionated or low-molecular weight heparins in patients with acute stroke. The relative risk of hemorrhagic transformation of the ischemic stroke is higher than the lowering of stroke due to recurrent embolism. Large infarcts, greater patient age, extensive small vessel disease and uncontrolled hypertension should prompt a further delay in anti-coagulation. CONCLUSION: Avoid anticoagulation with heparins in patients with acute ischemic stroke with atrial fibrillation for 7-10 days. Further studies are needed to delineate when to start oral anticoagulation.     

Underuse of Oral Anticoagulants in Atrial Fibrillation: A Systematic Review

Background

Atrial fibrillation is associated with substantial mortality and morbidity from stroke and thromboembolism. Despite an efficacious oral anticoagulation therapy (warfarin), atrial fibrillation patients at high risk for stroke are often under-treated. This systematic review compares current treatment practices for stroke prevention in atrial fibrillation with published guidelines.

Methods

Literature searches (1997-2008) identified 98 studies concerning current treatment practices for stroke prevention in atrial fibrillation. The percentage of patients eligible for oral anticoagulation due to elevated stroke risk was compared with the percentage treated. Under-treatment was defined as treatment of <70% of high-risk patients.

Results

Of 54 studies that reported stroke risk levels and the percentage of patients treated, most showed underuse of oral anticoagulants for high-risk patients. From 29 studies of patients with prior stroke/transient ischemic attack who should all receive oral anticoagulation according to published guidelines, 25 studies reported under-treatment, with 21 of 29 studies reporting oral anticoagulation treatment levels below 60% (range 19%-81.3%). Subjects with a CHADS₂ (congestive heart failure, hypertension, age >75 years, diabetes mellitus, and prior stroke or transient ischemic attack) score ≥2 also were suboptimally treated, with 7 of 9 studies reporting treatment levels below 70% (range 39%-92.3%). Studies (21 of 54) using other stroke risk stratification schemes differ in the criteria they use to designate patients as “high risk,” such that direct comparison is not possible.

Conclusions

This systematic review demonstrates the underuse of oral anticoagulation therapy for real-world atrial fibrillation patients with an elevated risk of stroke, highlighting the need for improved therapies for stroke prevention in atrial fibrillation.     

Atrial Fibrillation and Deterioration in Cognitive Function

The link between atrial fibrillation and cognitive decline and dementia has gained interest of the medical community lately. More research is being conducted to prevent and or delay this morbidity as no curative therapy is available for cognitive decline and dementia. The exact mechanism of causation is unclear. Multiple pathophysiological mechanisms have been implicated. Lately, treatment for atrial fibrillation including anticoagulation and catheter ablation therapies have shown to decrease the risk of deterioration of cognitive function. In this review we summarize epidemiologic studies linking the association, potential mechanisms, and impact of various modalities of therapy of atrial fibrillation on cognitive function outcomes.     

Management of acute ischaemic stroke in patients with dementia

An estimated 10% of stroke patients have an underlying dementia. As a consequence, health professionals often face the challenge of managing patients with dementia presenting with an acute stroke. Patients with dementia are less likely to receive thrombolysis (0.56–10% vs. 1–16% thrombolysis rates in the general population), be admitted to a stroke unit or receive some types of care. Anticoagulation for secondary stroke prevention is sometimes withheld, despite dementia not being listed as an exclusion criterion in current guidelines. Studies in this population are scarce, and results have been contradictory. Three observational studies have examined intravenous thrombolysis for treatment of acute ischaemic stroke in patients with dementia. In the two largest matched case–control studies, there were no significant differences between patients with and without dementia in the risks of intracerebral haemorrhage or mortality. The risk of intracerebral haemorrhage ranged between 14% and 19% for patients with dementia. Studies of other interventions for stroke are lacking for this population. Patients with dementia are less likely to be discharged home compared with controls (19% vs. 41%) and more likely to be disabled (64% vs. 59%) or die during hospitalization (22% vs. 11%). The aim of this review was to summarize current knowledge about the management of ischaemic stroke in patients with pre‐existing dementia, including organizational aspects of stroke care, intravenous thrombolysis, access to stroke unit care and use of supportive treatment. Evidence to support anticoagulation for secondary prevention of stroke in patients with atrial fibrillation and antiplatelet therapy in nonembolic stroke will be discussed, as well as rehabilitation and how these factors influence patient outcomes. Finally, ethical issues, knowledge gaps and pathways for future research will be considered.     

Kann die Indikation zur Antikoagulation durch die Katheterablation von Vorhofflimmern ersetzt werden?

Current guidelines recommend continuation of oral anticoagulation (OAC) for at least 3 months post catheter ablation of atrial fibrillation. Afterwards long-term OAC is determined according to individual thromboembolic risks, regardless whether patients experience arrhythmia recurrences or not. This proceeding arises from difficulties to reliably detect arrhythmia recurrences after catheter ablation. Retrospective studies indicate the safety of switching patients from OAC to aspirin, as long as patients do not have major thromboembolic risk factors (stroke, age >75 years) and experience freedom from atrial fibrillation. Prospective studies are needed to determine the optimal anticoagulation approach in patients following successful catheter ablation. Especially the treatment with aspirin as an alternative to OAC needs to be critically assessed as OAC is much more effective with respect to stroke reduction without being associated with significant differences in bleeding risk.     

心房颤动患者的抗凝治疗

心房颤动是临床实践中最常见且危害严重的心律失常,是缺血性脑卒中的最主要危险因素之一。有效的抗凝治疗可显著降低心房颤动患者缺血性脑卒中的发生率,成为心房颤动患者治疗策略的重中之重。新型口服抗凝剂为心房颤动患者的抗凝治疗提供了更多选择。现结合近年发表的相关文献对心房颤动患者的抗凝治疗进行综述。     

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...     

Anticoagulation in management of atrial fibrillation

Atrial fibrillation is the most common cardiac arrhythmia in adults. The prevalence of atrial fibrillation rises with age, reaching as high as 9% in those 70 years and older. Currently there are 2.2 million affected people in the United States, with twice the mortality rate of age-matched controls in sinus rhythm. Epidemiologic studies show atrial fibrillation to be responsible for as many as 15% of the total number of strokes, a higher incidence of dementia, cardiac function compromise, and decreased quality of life. Recent studies indicate that rate control and rhythm restoration are equally effective strategies in the treatment of atrial fibrillation, with a trend toward better survival in patients treated for rate control and anticoagulation. Data from several randomized controlled studies on stroke prophylaxis provided consistent evidence of the superiority of adjusted-dose warfarin over aspirin. Guidelines developed by the American College of Cardiology, the American Heart Association, the European Society of Cardiology, and ACCP provide a convenient decision-making framework for the practicing physician. The safety and effectiveness of anticoagulation in clinical practice were found to be equal to those in major trials with rigorous controls. Despite the proven effectiveness and safety of oral anticoagulation for thromboembolism prophylaxis in atrial fibrillation, warfarin remains underused, especially among the elderly (75 years and older), who are at the greatest risk of stroke and would likely benefit the most from prophylactic anticoagulation.     

The Evolving Role of Stroke Prediction Schemes for Patients With Atrial Fibrillation

Our approach to managing patients with atrial fibrillation has changed substantially over the past 10 years, as a result of numerous high-quality observation studies and randomized trials. In this article, we will provide practical guidance for the use of oral anticoagulation therapy in patients with atrial fibrillation. We will review the evolution of stroke and bleeding risk prediction schemes and discuss their role in patient care. Initially, stroke prediction schemes were used to identify patients with atrial fibrillation at the highest risk of stroke, in whom the use of oral anticoagulant therapy was believed to be the most important. However; with the advent of new, safer, and more convenient oral anticoagulant drugs, the role of these schemes has shifted to the identification of the lowest risk patients, representing the minority of patients with atrial fibrillation, in whom oral anticoagulant therapy is not recommended. At the same time, schemes were developed to predict bleeding, the major risk of oral anticoagulant therapy. However; use of these schemes has been limited by their complexity and significant correlation with stroke schemes. In general, it is advisable to base the decision to use oral anticoagulation on the patient's stroke risk and use bleeding schemes to identify absolute contraindications or modifiable risk factors for bleeding. Prediction schemes have been useful clinical tools, invaluable in the design of clinical trials, and have assisted greatly in economic analyses. However, the nature and role of such schemes is now adapting to the current era of novel oral anticoagulant agents.     

Anticoagulation in atrial fibrillation and flutter.

Atrial fibrillation and atrial flutter are important risk factors for stroke. Based on a literature search, pathogenesis of thromboembolism, risk assessment in patients, efficacy of anticoagulation therapy and its alternatives are discussed. Special emphasis is put on issues like paroxysmal atrial fibrillation, atrial flutter and anticoagulation surrounding catheter ablation and cardioversion. A strategy for anticoagulation around the time of pulmonary vein ablation is suggested.     

Atrial fibrillation. Thromboembolic risk and indications for anticoagulation

The risk of embolic stroke in patients with atrial fibrillation is largely related to the underlying disorders responsible for the arrhythmia. Atrial fibrillation associated with rheumatic mitral valve disease has the highest stroke risk (about 17 times greater than unaffected controls), but even with nonvalvular heart disease, the risk is increased fivefold. The stroke risk is greater with chronic than with paroxysmal atrial fibrillation, is highest in the year after onset of the arrhythmia, and is lower in younger patients with idiopathic ("lone") atrial fibrillation. Major bleeding episodes, the most important risk of anticoagulation, occur in about 5% to 10% of patients. The decision to anticoagulate a patient with atrial fibrillation depends on the cause of the arrhythmia, especially any associated cardiovascular disease, and the individual's risk from anticoagulation. Growing evidence supports the effectiveness of anticoagulation of most patients with nonvalvular, as well as valvular, cardiac disease for the prevention of both primary and recurrent strokes.