New Approaches to the Management of Atrial Fibrillation
1998; Lippincott Williams & Wilkins; Volume: 98; Issue: 16 Linguagem: Inglês
10.1161/01.cir.98.16.1594
ISSN1524-4539
Autores Tópico(s)Cardiac electrophysiology and arrhythmias
ResumoHomeCirculationVol. 98, No. 16New Approaches to the Management of Atrial Fibrillation Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBNew Approaches to the Management of Atrial Fibrillation The Role of the Atrial Defibrillator Mark E. Josephson Mark E. JosephsonMark E. Josephson From the Harvard-Thorndike Electrophysiology Institute and Arrhythmia Service, Beth Israel Deaconess Medical Center, Boston, Mass. Originally published20 Oct 1998https://doi.org/10.1161/01.CIR.98.16.1594Circulation. 1998;98:1594–1596Atrial fibrillation (AF) is the most common arrhythmia for which patients are hospitalized.1 It imposes important morbidity and mortality on patients' lives, engendering enormous expenditures for its management. The frequency of AF increases with age (10% in patients >70 years old) and with the presence of congestive heart failure (up to 25%). Clinically, the appearance of AF may be associated with a variety of symptoms, including palpitations, heart failure, syncope, and chest pain, which occur primarily because of the heart rate. In addition, AF imposes an important risk of thromboembolism and the potential for the development of tachycardia-mediated cardiomyopathy. It has been estimated by some that nearly 40% of strokes in patients >70 years old may be a result of AF.2 Whereas the financial burden imposed by AF itself is enormous, the added cost of caring for its sequelae, particularly cerebrovascular accidents, makes successful management of AF imperative.34Heretofore, the management of AF has been empirical and not very effective. Physicians are divided as to whether it is more important to maintain sinus rhythm or control the heart rate. The choice of therapy is dependent on the physician caring for the patient: internists, cardiologists, and electrophysiologists may choose different regimens.Studies evaluating rate control by use of drugs singularly or in combination have shown that 50% of patients demonstrate adequate rate control with pharmacological therapy. Use of antiarrhythmic agents to prevent AF and maintain sinus rhythm is fraught with lack of efficacy, intolerance, and potentially lethal side effects. Although many studies have demonstrated that anticoagulation with coumarin can reduce the risk of thromboembolic phenomena, that risk is only reduced to perhaps 1% per year, approximately the same as the risks of coumarin.5 Thus, in my opinion, the most desirable therapy would be the use of some therapy that maintains sinus rhythm and eliminates the need for anticoagulation. This is supported by a Markov model of AF management.6Because drugs have shown limited efficacy and significant side effects, interest in the development of nonpharmacological therapy for AF has arisen. At the present time, ablation of the AV node with pacemaker implantation is an accepted form of rate control that definitely works, is associated with hemodynamic benefits, and does not require drugs, with their attendant side effects.7 This form of therapy, although it is usually used for drug-refractory cases, may in fact become a procedure of choice in patients who need pacemakers because of brady-tachy syndrome and, in particular, those who have cardiomyopathies and AF with rapid responses, in whom β-blockers and calcium blockers may be more detrimental to their hemodynamic function. In patients with the sick sinus syndrome, atrial pacing has been shown to be beneficial compared with ventricular pacing for prevention of the development of chronic AF, decreasing mortality and thromboembolic events.8 More recent data suggest that dual-site right atrial pacing, bicameral pacing, and coronary sinus pacing alone may be more useful in preventing AF than high right atrial rate pacing alone.91011The poor success of maintenance of sinus rhythm with drugs and subsequent thromboembolic sequelae have even led to the development of a surgical procedure (the maze operation) that compartmentalizes the atrium so that it cannot fibrillate.12 Although this procedure can achieve sinus rhythm, it carries with it significant morbidity, and the actual hemodynamic and antithrombotic benefits of sinus rhythm with abnormal atrial contraction are not clear. Catheter techniques are also currently being used to mimic the maze procedure.13 These procedures have significant morbidity and an unknown success rate of maintaining sinus rhythm. At this time, they should be considered experimental. Recent observations have demonstrated that focal atrial tachycardias or atrial premature complexes can precipitate some cases of paroxysmal AF.14 In such instances, these atrial tachycardias and/or atrial premature complexes have been successfully ablated and prevented AF.14 Other investigators have demonstrated that a combination of drugs that convert AF to atrial flutter combined with a simple flutter ablation can restore and maintain sinus rhythm and does not result in impaired atrial function.15Over the past several years, evidence has accumulated that electrical and anatomic remodeling of the atrium occurs during the initial periods of AF.16 This has led to the concept that AF begets AF, which in turn suggests that early restoration of sinus rhythm might decrease the recurrence rate of AF or even, in some cases, prevent its recurrence. About the same time, it was demonstrated that internal cardioversion could successfully restore sinus rhythm in patients in whom external cardioversion could not.17 Although these initial studies required high energies delivered between a lead in the right atrium and a patch on the chest, Levy et al18 subsequently demonstrated that low-energy (3-J) shocks between a right atrial and a coronary sinus coil using biphasic waveforms could convert AF, particularly when it was present for 1 year's duration are probably also not ideal candidates.What is the future role of an atrial defibrillator? Recent advances have suggested that atrial pacing may prevent AF and that either dual-site, bicameral, or coronary sinus pacing alone may be beneficial.91011 A natural evolution of the current Atrioverter would be to have pacing capability in addition to defibrillation capability. The combination of a device capable of dual-chamber pacing and atrial defibrillation, with or without pharmacological agents, will increase the patient population in whom the Atrioverter could be used and ensure a higher incidence of prevention of AF. The concept of atrial defibrillation is also applicable to patients with primary ventricular arrhythmias who also have AF. Perhaps 5% to 20% of patients requiring ventricular ICDs have coexistent AF. A combined atrial and ventricular defibrillator system with dual-chamber pacing might be very useful for this group of patients. Such a device, the Jewel AF, is available in Europe as an investigational system. It is unclear what type of device should be used in patients who have a substrate for ventricular arrhythmias but have never experienced an episode. The Atrioverter has a high safety record in patients without a known ventricular arrhythmia substrate, but it is not known how safe it will be in patients with organic heart disease. The manufacturer is now doing a similar study of the Atrioverter in patients with organic heart disease but without prior ventricular arrhythmias to assess its safety in such patients. Whether or not this device alone will be safe or whether such patients will require ventricular defibrillation backup is unknown.In summary, it is clearly established that low-energy internal cardioversion can successfully convert AF to sinus rhythm. Time will tell whether early conversion of sinus rhythm will actually decrease the frequency of AF, and we are awaiting data about this important outcome. Concerns will always exist related to costs, efficacy, and safety in all patient populations, as well as tolerability, particularly in patients who have high defibrillation thresholds and require multiple shocks. Present indications for the device include recurrent symptomatic, drug-refractory AF in the absence of a substrate of ventricular arrhythmia in patients in whom the episodes require cardioversion every 1 to 2 months. Expansion of these indications is on the horizon. This will be especially true when the system is combined with dual-chamber pacing and drugs. If proven safe in patients with organic heart disease, such a device, particularly with dual-chamber pacing, may be a primary potential therapeutic option or a component of hybrid therapy in patients with recurrent symptomatic AF and mild to moderate heart failure aggravated by AF, those with AF and hypertrophic cardiomyopathy, those with recurrent AF who have a high embolic risk who are poor candidates for anticoagulation, and those with AF-induced syncope or angina, perhaps in combination with linear RF ablations, which reduce the frequency of episodes and lower defibrillation thresholds.The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.FootnotesCorrespondence to Mark E. Josephson, MD, Director, Harvard-Thorndike Electrophysiology Institute and Arrhythmia Service, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215. 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Guo H, Bajwa O and Olshansky B (2001) Atrial Fibrillation: Practical Approaches Cardiology for the primary care Physician, 10.1007/978-1-4615-6601-4_46, (427-439), . October 20, 1998Vol 98, Issue 16 Advertisement Article InformationMetrics Copyright © 1998 by American Heart Associationhttps://doi.org/10.1161/01.CIR.98.16.1594 Originally publishedOctober 20, 1998 KeywordsEditorialsdefibrillationfibrillationPDF download Advertisement
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