Current Strategies in the Management of Atrial Fibrillation (original) (raw)

Atrial Fibrillation

Cardiology Research and Practice, 2013

Atrial �brillation (AF) is the most common clinically important cardiac arrhythmia. e prevalence of AF roughly doubles with each advancing decade of age, from 0.5% at age of 50-59 years to almost 9% at age of 80-89 years [1]. AF is associated with substantial morbidity and mortality. us, AF is a signi�cant risk factor for ischemic stroke and accounts for 15-20% of all strokes [2]. Considering the clinical relevance of AF, this journal initiated a special issue dealing with the recent developments in AF over the past few years. is issue contains important work-both review and original articles-addressing the epidemiology, economic impact of AF, and new therapeutic/diagnostic developments and their potential clinical implications. e general therapeutic strategies in AF include heart rate or rhythm control and anticoagulation. Current drugs used for AF therapy have major limitations, including incomplete efficacy and risks of life-threatening proarrhythmic events and bleeding complications. However, there have been several recent advancements in therapy of AF. ey included the availability of new anticoagulants, such as dabigatran, rivaroxaban, and apixaban, as well as guideline changes to incorporate the catheter-based isolation of pulmonary veins (PV) as a class IIa/A indication [3]. Since the �rst paper evidencing the role of PV as triggers of AF [4], various ablation techniques targeting PV (focal ablation, PV isolation, circumferential antral ablation, cryoballoon) were introduced into clinical practice [5, 6]. ough PV isolation by catheter-based radiofrequency ablation has become an effective treatment option in AF, the studies on long-term outcomes are still limited and less encouraging. Recently, F. Ouyang et al. examined 5-year outcomes in paroxysmal AF and found that sinus rhythm was present in

Atrial fibrillation: Epidemiology, mechanisms, and management

Current Problems in Cardiology, 2000

~ ften associated with an adverse prognosis, atrial fibrillation (AF) is a common and troublesome arrhythmia, 1-22 and its electrocardiographic (ECG) characteristics are relatively well recognized. It is characterized by chaotic, rapid, discontinuous atrial depolarizations, resulting in rapid oscillations that are recorded as irregularly formed f waves in contrast to uniform P waves of sinus or other distinct supraventricular rhythms (Fig 1). AF is a dysrhythmia of the atria, in which the atria stop contracting as they begin to fibrillate, or quiver, and become ineffectual in filling the ventricles, disrupting ventricular function, and subsequently, cardiac output. When sinus rhythm ceases to be the heart's driving force, ventricular responses also become irregular, reflecting the atrium's chaotic electrical activity. The ventricular irregular contractions, which have become either too fast or too slow, impair the cardiac pump, leading to a variety of symptoms usually attributable to these hemodynamic variances. Even patients with asymptomatic AF have high incidences of such complications as stroke, congestive heart failure (CHF), and cardiomyopathy. The degree of irregularity in ventricular rate depends on several factors, including innate properties of the atrioventricular (AV) node, levels of sympathetic or parasympathetic stimulation, and whether therapies are aimed at treating AF through modifying properties of the AV node or those of the atria, or are simply aimed at treating concomitant conditions. Although certain populations are more prone than others to develop AF, its causes and mechanisms are not easily understood, and the terminology for its classification varies significantly. 2m2 The following classification system is used for this review: Paroxysmal: Episodes are <7 days long, interspersed with periods of sinus rhythm, and (the hallmark of paroxysmal AF) usually terminate spontaneously (paroxysmal AF, although self-terminating, may be recurrent). Persistent: Intervention is needed to restore sinus rhythm. Permanent or chronic: No spontaneous conversion; interventions to restore sinus rhythm are either ineffectual or not tried. At any given time, the classification of an AF, and hence the proper treatment protocol, falls somewhere on the above spectrum. Data from the Cardiovascular Atrial septal defect Cardiac surgery disease Cardiomyopathy: hypertrophic Idiopathic Infiltrative Hypertension Ischemic heart disease: acute and chronic Alcohol ("holiday heart" syndrome) Cerebral vascular accident Chronic pulmonary disease Defibrillation Effort Electrocution Electrolyte abnormalities Rare Acute hypovolernia Congenital Multiple sclerosis Muscular dystrophy Mltral valve prolapse Nonrheumatic mitral or tricuspid valve disease Pericarditis Rheumatic heart disease Tachycardia-bradycardia syndrome Tumors, lipomatous or hypertrophic Wolff4~arkinson-W hlte syndrome Fever Hypothermia Pneumonia Pulmonary embolism Sudden emotion Thyrotoxicosis Trauma Pheochromocytoma Right atrial cold injection Swallowing Tyramine-containing foods From Stanton MS, Miles WM, Zipes DO. Atrial fibrillation and flutter. In: Zipes DP, Jalife J, editors. Cardiac electrophysiology from cell to bedside. Philadelphia: WB Saunders; 1990. p. 735-42. infarction (MI) 18.23 and may be self-limiting. In the CARAF study, 198 (18.2%) of 1086 patients who were entered into the registry during 1991-1995 developed AF after open-heart surgery, whereas the AF of the remaining 888 was not surgically related. Noncardiac conditions associated with AF include, but are not limited to, hyperthyroidism, diabetes mellitus, alcohol intoxication, use of cholinergic drugs, and pulmonary diseases, as are such factors as exercise, emotional stress, fever, electrocution, hypothermia, trauma, and muscular dystrophy (Table 1). 11,24-29 Much of our knowledge about the incidence of AF is derived from the Framingham Study, which despite possible limitations of ethnic and racial bias related to the population studied, remains one of the single most important references for AE When the study started, there were 2090 men and 2641 women, ages 55 to 94 years. Thirty-eight years later, in 1994, 11.8% (562 patients) had documented AF, of whom 53% (298) were women. The incidence was higher in men (12.6%) than in women (11.3%). A 1991 report from this study noted that AF was more prevalent in older adults (ages 80 to 89), a 9% incidence, than in younger ones (ages 50 to 59), a 0.5% incidence, and this relationship continued in 1994, when there were 6.2 cases of AF documented for every 1000 examinations in

Pathogenesis of AF: impact on intracardiac signals

2011

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and is responsible for the highest number of rhythm-related disorders and cardioembolic strokes worldwide. Intracardiac signal analysis during the onset of paroxysmal AF led to the discovery of pulmonary vein as a triggering source of AF, which has led to the development of pulmonary vein ablation-an established curative therapy for drug-resistant AF. Complex, multicomponent and rapid electrical activity widely involving the atrial substrate characterizes persistent/permanent AF. Widespread nature of the problem and complexity of signals in persistent AF reduce the success rate of ablation therapy. Although signal processing applied to extraction of relevant features from these complex electrograms has helped to improve the efficacy of ablation therapy in persistent/permanent AF, improved understanding of complex signals should help to identify sources of AF and further increase the success rate of ablation therapy.