Nonvalvular atrial fibrillation associated with cardioembolic stroke: the role of hypertensive heart disease

Abstract Epidemiologists have not identified high risk groups nor the entire spectrum of heart disease, especially the subclinical forms underlying nonvalvular atrial fibrillation (NVAF) predisposing to cardioembolic (CE) stroke. We analysed 36 cases of ‘isolated’ NVAF among 106 consecutive cases of CE stroke after excluding cases of AF associated with valvular disease, myocardial infarcts, ischaemic and other cardio-myopathies (34 cases). This revealed echocardiographic left ventricular hypertrophy (LV mass index 136 ± 25 g, vs normal 68 ± 12 g p < 0.001), enlarged left atria (left atrial area 27.4 ± 3.6 cm² vs normal 14.3 ± 1.6 cm²p < 0.001), normal systolic function and formed the largest group associated with CE stroke (34%), mean age 72.6 years – Study Group D. Eighty nine per cent had known or undetected hypertension compared to 60% in matched controls (x²= 8.3 df= 1 p < 0.01), and hypertension remained the predominant risk factor for left ventricular hypertrophy (LVH). Although all had echocardiographic LVH, 60% had neither electrocardiographs LVH nor cardiomegaly on chest X-ray. Hence usual epidemiologic methods may fail to detect these cases. Hypertensive heart disease is known to predispose to left atrial enlargement and AF. Progressive atrial enlargement is associated with increasing risk of embolie stroke. We conclude that NVAF associated with hypertensive heart disease forms a major component of the spectrum of heart disease associated with NVAF predisposing to CE stroke. Detection and treatment of hypertension to prevent or reverse LVH and atrial enlargement should be an important preventive measure.     

心房颤动总是"引发"心房颤动吗?

心房颤动(AF)是临床上常见的心律失常,心房重构和AF"引发"AF概念的提出是对AF病理生理机制研究的重大进展,但临床上有关AF的诸多问题并不能都用AF"引发"AF和单纯的心房电重构来解释,本文就AF"引发"AF这一问题结合有关文献作一综述.     

New-onset atrial fibrillation

Patients with new-onset atrial fibrillation are often hospitalized emergently. To determine whether this is necessary, the authors retrospectively reviewed the care of 97 consecutive patients with this illness. No reason for the atrial fibrillation in 43 patients could be identified. Hypertension, coronary artery disease, and valvular heart disease were the most commonly associated conditions; myocardial infarction occurred in one patient. In 82% of patients, atrial fibrillation reverted to normal sinus rhythm during hospitalization. Three patients needed emergent hospitalization irrespective of the presence of atrial fibrillation. In the remainder, admission was based solely on the diagnosis of new-onset atrial fibrillation. Ninety-eight per cent had an uncomplicated hospital course. It is concluded that hospitalization is not necessary for all patients with new-onset atrial fibrillation. Those in whom reversion to normal sinus rhythm occurs rapidly during digoxin therapy can be discharged. Where no major medical illness is evident patients can be admitted to a bed outside the intensive care unit until reversion to normal sinus rhythm or rate control is achieved. Received from the Department of Medicine, North Shore University Hospital, Manhasset, New York, and the Departments of Medicine and Pharmacology, Cornell University Medical College, New York, New York. Supported in part by a grant from the Pharmaceutical Manufacturers Association Foundation.     

Cardioversion in atrial fibrillation. Focus on recent-onset atrial fibrillation

Atrial fibrillation is the most common sustained arrhythmia encountered in clinical practice. Its prevalence is rising due to an increasing elderly population and the improvement in management of life-threatening diseases such as myocardial infarction and heart failure. Over the past few years effective non-pharmacological treatments, new antiarrhythmics drugs, and anticoagulants have been introduced. Regardless of rate-control or rhythm control strategy, adequate stroke prevention still remains a cornerstone in the treatment of this arrhythmia. This review aims to illustrate the main practical issues in the management of atrial fibrillation, focusing on patients with recent-onset and hemodynamically stable atrial fibrillation.     

Drug-induced atrial fibrillation

Atrial fibrillation (AF) is the most common sustained rhythm disorder observed in clinical practice and predominantly associated with cardiovascular disorders such as coronary heart disease and hypertension. However, several classes of drugs may induce AF in patients without apparent heart disease or may precipitate the onset of AF in patients with preexisting heart disease. We reviewed the literature on drug-induced AF, using the PubMed/Medline and Micromedex databases and lateral references. Successively, we discuss the potential role in the onset of AF of cardiovascular drugs, respiratory system drugs, cytostatics, central nervous system drugs, genitourinary system drugs, and some miscellaneous agents. Drug-induced AF may play a role in only a minority of the patients presenting with AF. Nevertheless, it is important to recognize drugs or other agents as a potential cause, especially in the elderly, because increasing age is associated with multiple drug use and a high incidence of AF. This may contribute to timely diagnosis and management of drug-induced AF.     

Deglutition-induced atrial fibrillation

We present the case of 38-year-old woman who experienced palpitations on swallowing, which were later found to be atrial fibrillation. Her symptoms improved on treatment with disopyramide and verapamil. Within 9 months, she was weaned from both medications without recurrence of symptoms.     

Postoperative atrial fibrillation

Postoperative atrial fibrillation is associated with significant morbidity, longer hospital stay, and higher related costs. Although the etiologic mechanism of postoperative atrial fibrillation and its optimum method of prophylaxis or management are not well defined, progress has been made during the past decade. This review focused on recent findings leading to a better understanding of the mechanisms and management of atrial fibrillation after surgery and current approaches directed at prevention of thromboembolic sequelae. Because postoperative atrial fibrillation is a frequent complication, preoperative risk assessment algorithms are being proposed to minimize the number of patients in whom an intervention to prevent atrial fibrillation is undertaken, and thus, reduce toxicity due to antiarrhythmic drug therapy. Finally, current data suggest that once atrial fibrillation has occurred, a rate-control strategy during the first 8 to 12 hours is reasonable because 50% of those episodes will resolve during this period. Beyond this period, a more aggressive approach using class IC or III antiarrhythmic drugs will hopefully reduce the number of patients requiring anticoagulation and prolonged drug therapy.     

阵发性房颤随访情况和阵发性房颤进展的危险因素

目的 观察阵发性房颤的随访情况和分析阵发性房颤进展的危险因素。方法 对216例阵发性房颤患者进行随访,观察其主要结局（是否发生房颤进展）和临床事件（卒中、心力衰竭、再住院和出血事件）,再按是否房颤进展分为房颤进展组（n=87）和房颤未进展组（n=129）。采用巢式病例对照研究方法,进行单因素分析和多因素分析（采用多因素Logistic回归模型）,分析影响房颤进展的危险因素。结果 216例阵发性房颤患者经过3.45年（中位数）随访发生房颤进展者87例,其发生进展率为40.2%,年进展率为11.7%。房颤进展组脑卒中、心力衰竭、房颤相关的再住院发生率均显著高于房颤未进展组（分别17% vs. 6%,18% vs. 5%,37% vs. 17%, 分别P<0.05,P<0.01和P<0.01）;两组间病死率及出血发生率差异未达到显著水平。多因素分析显示,年龄(OR 1.082,95%CI 1.016-1.392,P<0.05)、左房内径>45 mm(OR 2.339,95%CI 1.445-3.785,P<0.05)、CHADS2评分>3分(OR 1.382,95%CI 1.081-1.987,P<0.05)以及超敏C反应蛋白（hs-CRP）水平(OR 1.124,95%CI 1.005-2.345,P<0.05 )是房颤进展的独立危险因素。结论 阵发性房颤进展的年发生率为11.6%。影响房颤进展的独立危险因素为年龄、左房内径、hs-CRP水平及CHADS2评分。     

Predictors of atrial fibrillation recurrence in patients with long-lasting atrial fibrillation

BACKGROUND:

Limited data are available on the predictors of atrial fibrillation (AF) recurrence in patients with chronic AF.

OBJECTIVES:

To evaluate potential clinical, echocardiographic and electrophysiological predictors of AF recurrence after internal cardioversion for long-lasting AF.

METHODS:

A total of 99 consecutive patients (63 men and 36 women, mean age 63.33±9.27 years) with long-standing AF (52.42±72.02 months) underwent internal cardioversion with a catheter that consisted of two defibrillating coils. Shocks were delivered according to a step-up protocol. Clinical follow-up and electrocardiographic recordings were performed on a monthly basis for a 12-month period or whenever patients experienced symptoms suggestive of recurrent AF.

RESULTS:

Ninety-three patients (93.94%) underwent a successful uncomplicated cardioversion, with a mean atrial defibrillation threshold of 10.69±6.76 J. Immediate reinitiation of AF was observed in 15 patients (15.78%) of whom a repeated cardioversion restored sinus rhythm in 13 cases. Early recurrence of AF (within one week) was observed in 12 of 93 patients (12.90%). At the end of the 12-month follow-up period, during which seven patients were lost, 42 of the 86 remaining patients (48.84%) were still in sinus rhythm. Multivariate regression analysis showed that left atrial diameter (OR 1.126, 95% CI 1.015 to 1.249; P=0.025) and mitral A wave velocity (OR 0.972, 95% CI 0.945 to 0.999; P=0.044) were significant and independent predictors of AF recurrence, whereas age, left ventricular ejection fraction and AF cycle length were not predictive of arrhythmia recurrence.

CONCLUSION:

The present study showed that the left atrial diameter and mitral A wave velocity are the only variables associated with AF recurrence after successful cardioversion.     

Initiation of ventricular fibrillation by atrial fibrillation

We report the case of a patient who developed spontaneouslya ventricular fibrillation during atrial fibrillation, 8 minafter a perfusion of isoproterenol was stopped Two mechanismscould explain the ventricular arrhythmia: silent ischaemia anda long-short cycle sequence just before ventricular fibrillation.     

Treatment of atrial fibrillation

Atrial fibrillation is a common and in most patients recurrent arrhythmia. Atrial fibrillation can increase mortality and causes at times severe symptoms in affected patients. Timely initiation of sustained oral anticoagulation is indicated in patients with atrial fibrillation at risk for stroke to prevent thromboembolic complications. Patients at risk for stroke can be identified by clinical characteristics using validated score systems, e.g., the CHADS(2) score or the Framingham score. Drugs that slow AV nodal conduction can improve symptoms associated with high ventricular rate. Cardioversion can acutely terminate atrial fibrillation in almost all patients, but many patients suffer from recurrent atrial fibrillation. The prevention of arrhythmia recurrences ("rhythm control therapy") is indicated in patients with severe arrhythmia-related symptoms. Antiarrhythmic drugs can approximately double the maintenance rate of sinus rhythm. Other drugs that were not primarily developed as antiarrhythmic agents, e.g., ACE inhibitors, sartans, and possibly statins, can further improve maintenance of sinus rhythm in selected patient groups. Catheter-based isolation of the pulmonary veins is a recently developed intervention that can cure some forms of atrial fibrillation. It is likely that a multimodal therapeutic approach will in the future allow rhythm control therapy to become more effective.     

动脉粥样硬化与心房颤动

心房颤动（房颤）是临床上最常见的心律失常,不仅可以引起患者心功能不全且易发生血栓栓塞并发症,增加致残率和病死率。动脉粥样硬化是冠心病和缺血性脑卒中的主要病因。近年来研究表明,动脉粥样硬化对于房颤发生、发展和复发有一定预测作用,而房颤会促进动脉粥样硬化进展,增加血栓栓塞和动脉粥样硬化栓塞风险,但机制尚不完全清楚。目前,通过影像学、电生理学、血清学、组织病理学、免疫学等方法发现两者都可能与炎症反应、动脉内皮损伤或功能不全等因素有关,并可能相互影响。     

Obesity and atrial fibrillation

Atrial fibrillation (AF) is an increasing public health problem, often described as the epidemic of the new millennium. The rising health economic impact of AF, its association with poor quality of life and independent probability of increased mortality, has recently been highlighted. Although population ageing is regarded as an important contributor to this epidemic, obesity and its associated cardiometabolic comorbidities may represent the principal driving factor behind the current and projected AF epidemic. Obesity‐related risk factors, such as hypertension, vascular disease, obstructive sleep apnea and pericardial fat, are thought to result in atrial electro‐structural dysfunction. In addition, insulin resistance, its associated abnormalities in nutrient utilization and intermediary metabolic by‐products are associated with structural and functional abnormalities, ultimately promoting AF. Recent elucidation of molecular pathways, including those responsible for atrial fibrosis, have provided mechanistic insights and the potential for targeted pharmacotherapy. In this article, we review the evidence for an obesity‐related atrial electromechanical dysfunction, the mechanisms behind this and its impact on AF therapeutic outcomes. In light of the recently described mechanisms, we illustrate proposed management approaches and avenues for further investigations.