Nonpharmacologic therapies for atrial fibrillation

Catheter ablation of atrial fibrillation

Following the advent of the surgical maze procedure, several catheter techniques have been developed to provide permanent prophylaxis against atrial fibrillation. These noninvasive techniques work by compartmentalizing the atria, by ablating the arrhythmogenic foci, or by isolating the atria from these foci. Although still at an early stage of development, preliminary results using focal ablation and circumferential ablation show extreme promise.

Hybrid Therapy with Right Atrial Catheter Ablation and Previously Ineffective Antiarrhythmic Drugs for the Management of Atrial Fibrillation

BACKGROUND

Many patients with paroxysmal atrial fibrillation (AF) become refractory to antiarrhythmic drugs (AADs). Early studies suggested that linear catheter ablation in the right atrium may provide sufficient substrate modification to reestablish therapeutic efficacy of previously ineffective AADs.

METHODS

This prospective before-after multicenter trial evaluated the safety and effectiveness of hybrid therapy that included right atrial catheter ablation coupled with a regimen of previously ineffective AADs on AF episode frequency and symptoms in drug refractory patients with paroxysmal AF. A standard linear lesion set (lateral, septal, isthmus) was used in all subjects. AF episode frequency, clinical arrhythmia symptoms, condition-specific (AFSS) and global health-related quality of life (SF-36) were assessed prior to ablation and at 6 months.

RESULTS

Ninety-three subjects, refractory to an average 2.9 AADs at baseline, qualified for inclusion and underwent right atrial catheter ablation. Eighty-four subjects (90%) provided 6 month AF episode frequency data which demonstrated a significant decrease compared to baseline (3.4 vs. 9.5, p < 0.0001). Forty-nine subjects (58%) were considered a clinical success by virtue of achieving a pre-specified target level episode frequency reduction of 50% or greater. Substantial and statistically significant improvements were realized almost uniformly for all measured arrhythmia symptoms as well as for both quality of life measures. The incidence of major complications was 5.4%.

CONCLUSIONS

The addition of right atrial catheter ablation to a regimen of previously ineffective AADs is associated with a significant reduction in the frequency, duration and severity of AF episodes and symptoms.

New approaches to atrial fibrillation management: a critical review of a rapidly evolving field

Atrial fibrillation (AF) is the most common cardiac arrhythmia, the prevalence of which is increasing with the aging of the population. Because of its clinical importance and the lack of highly satisfactory management approaches, AF is the subject of active clinical and research efforts. This paper reviews recent and on-going developments in pharmacological and non-drug management of AF. The ideal therapeutic goal for AF is the production and maintenance of sinus rhythm. Comparative studies suggest that available class I and III drugs have comparable and modest efficacy for sinus rhythm maintenance. Amiodarone, with actions of all antiarrhythmic classes, has recently been shown to have clearly superior efficacy compared with other available drugs. Newer agents are in development, but their advantages are as yet unclear and appear limited. A potentially interesting approach is the prescription of drugs upon the occurrence of an attack, rather than on a continuous basis. Recent insights into AF mechanisms may permit therapy to prevent development of the AF substrate. An alternative to sinus rhythm maintenance is a rate control approach, with no attempt to prevent AF. Drugs to effect rate control include digitalis, beta-blockers and calcium channel antagonists. Digitalis has limited value for control of exercise heart rate and for paroxysmal AF, but is particularly well suited for patients with concomitant AF and congestive heart failure. AV-nodal ablation and pacing is an effective alternative for rate control but leaves the patient pacemaker dependent. The relative merits of rate versus rhythm control are being evaluated in ongoing trials, preliminary results of which indicate no statistically significant differences in primary endpoints but highlight the risks of rhythm control therapy. In patients requiring pacemakers, physiological pacing (dual chamber devices or atrial pacing) has an advantage over purely ventricular pacemakers in AF prevention. Newer pacing modalities that produce more synchronised atrial activation, as well as pacemakers that prevent excessive atrial rate swings, show promise in AF prevention and may soon see wider use. The usefulness of automatic atrial defibrillators is presently limited by discomfort during shocks. Targeted destruction of pulmonary vein foci by radiofrequency catheter ablation suppresses paroxysmal AF. Efficacy in persistent AF is lower and still under study. Problems include potential recurrence in other veins and a small but nontrivial risk of pulmonary vein stenosis. Surgical division of the atria into zones with limited electrical connection, the MAZE procedure, is highly effective in AF prevention but is a major intervention that is not applicable to most patients. In conclusion, significant advances are being made in the management of patients with AF but much more work remains to be done.

Biatrial pacing for paroxysmal atrial fibrillation: a randomized prospective study into the suppression of paroxysmal atrial fibrillation using biatrial pacing

OBJECTIVES

The purpose of this study was twofold: to assess whether biatrial pacing is superior to single-site pacing and capable of reducing the frequency of episodes of paroxysmal atrial fibrillation (PAF); and to compare pacing of the proximal coronary sinus (PCS) with the distal coronary sinus (DCS) and the effects of sequential or simultaneous biatrial pacing.

BACKGROUND

Interatrial conduction abnormalities have a role in the initiation of PAF. Biatrial pacing alters the site and timing of atrial depolarization and may benefit those with drug-resistant PAF.

METHODS

Nineteen patients with PAF who were intolerant of or refractory to medication were studied. All received right atrial (RA) and coronary sinus (CS) leads (either PCS or DCS). For three months the pacemaker was set in sensing mode only. Subsequently each patient completed three-month periods in random order in the following modes: RA pacing, CS pacing, biatrial pacing using inter-atrial delays of 15 and 70 ms.

RESULTS

Sixteen patients received a benefit from one or more pacing modes. The greatest reduction in PAF episodes was seen during biatrial pacing, especially with leads sited at the high right atrium (HRA) and distal CS (p = 0.0048). There was no difference for sequential or simultaneous pacing. Three patients derived no benefit.

CONCLUSIONS

In selected patients, biatrial pacing causes a significant decrease in atrial fibrillation episodes. Optimal lead sites were at the HRA and DCS. Simultaneous pacing conferred no benefit over sequential pacing.

Atrial arrhythmias

Atrial arrhythmias are commonly encountered by the primary care clinician. They are usually asymptomatic or have only minor symptoms, unless the ventricular rate becomes very rapid. The challenges for the clinician are to recognize the benign from the more severe arrhythmias, to identify and treat the precipitating cause, to control the symptoms that concern the patient, and to prevent any complications. There are new medicinal and nonmedicinal treatments available that offer greater likelihood of acute and long-term success in the treatment, and sometimes cure, of the original arrhythmias.

Atrial fibrillation: nonpharmacologic approaches

Various nonpharmacologic interventions are available for patients with atrial fibrillation (AF) who are refractory to standard drug therapy. Atrioventricular junctional ablation and permanent pacing is a very effective therapy for patients with AF and a poorly controlled ventricular response. The surgical MAZE procedure has been performed on small numbers of patients but is remarkably successful in restoring and maintaining sinus rhythm. The role of permanent pacing as treatment for paroxysmal AF is undergoing evaluation and dual-site atrial pacing appears particularly promising in reducing the number of episodes of paroxysmal AF. Certainly the most exciting frontier in the treatment of AF is radiofrequency catheter ablation procedures. Our understanding of the mechanisms of paroxysmal AF and chronic AF has expanded enormously in the past 5 years. Radiofrequency lesions in pulmonary veins using standard technology will cure many cases of paroxysmal AF. However, catheter systems under development offer a great promise of treating most paroxysmal and chronic AF within the next few years. These developments will revolutionize our approach to this ever more prevalent clinical problem.