The Substrate Maintaining Persistent Atrial Fibrillation

Abstract

Complex fractionated atrial electrogram (CFAE) ablation is one successful approach for treating patients with persistent atrial fibrillation (AF), along with strategies that incorporate pulmonary vein isolation and linear lesions. In this issue of Circulation: Arrhythmia and Electrophysiology , Oral et al1 investigate the effect of right atrial CFAE focused ablation in patients with long-lasting persistent fibrillation. All patients had CFAE ablation in the left atrium and coronary sinus, and patients who did not convert to either sinus rhythm or atrial tachycardia were randomized to either additional right atrial CFAE ablation or to no further ablation. Patients were followed up for more than 1 year with similar outcomes in both groups, which suggests that right atrial CFAE ablation has no incremental benefit to targeting CFAE in the left atrium in persistent AF. Oral et al1 do acknowledge some limitations in their study design, which may have given a false-negative result. Page 6 Does the right atrial substrate play an important role in persistent AF, and how do we distinguish patients in whom the right atrium needs to be targeted as part of a catheter ablation strategy from those in whom the right atrium is unimportant? The Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society expert consensus document2 on catheter and surgical ablation of AF suggests that areas with CFAEs potentially represent AF substrate sites, ie, the atrial, venous, and ganglionic tissue that is critical in perpetuating or “driving” AF. Is this widely held assumption that CFAEs are related to the substrate correct? CFAEs are defined as electrograms displaying >2 deflections that are fractionated or have a short cycle length <120 ms,3 in their maximal form giving continuous electrical activity.4 Twenty years ago, such split potentials were observed after premature stimuli in patients with or without …