The stepwise ablation approach for chronic atrial fibrillation—Evidence for a cumulative effect

Abstract

Treatment options for atrial fibrillation (AF) have evolved from simple, fluoroscopy-guided pulmonary vein isolation for those patients with paroxysmal AF to complex, multi-modality procedures targeting not only anatomic structures but also electrophysiologic phenomena including complex fractionated electrograms, sites of dominant frequency and local non-venous drivers in patients with persistent and permanent AF. The stepwise ablation approach is a novel technique whereby structures contributing to initiation and maintenance of AF are sequentially targeted by radiofrequency ablation. Broadly divided into pulmonary veins, left atrial (LA) roof, left atrium (incorporating all anatomic regions of the chamber), mitral isthmus and non-LA structures, each region is targeted in sequence and the impact of ablation upon the global fibrillatory process assessed by measurement of AF cycle length (AFCL) at a site remote from the ablation target. In addition to pulmonary vein electrical disconnection and demonstrable complete conduction block across the roof and mitral isthmus lines (when performed), ablation is performed at those sites displaying continuous electrical and complex fractionated activity, with the endpoint of local organization, as well as at sites displaying electrograms consistent with focal sources driving AF. Ablation is accompanied by a cumulative increase in the AFCL prior to termination of AF by conversion either directly to sinus rhythm or to an atrial tachycardia which is then mapped conventionally and ablated. There is a ceiling of ablation within the LA beyond which further ablation is unlikely to result in a clinical benefit and should prompt evaluation of the contribution of the right atrium to maintenance of AF. The stepwise approach benefits from the integration of anatomic and electrophysiologic information to achieve a high level of success in termination of chronic AF by catheter ablation.

Pre-Procedural Prediction of Termination of Persistent Atrial Fibrillation by Catheter Ablation as an Indicator of Reverse Remodeling of the Left Atrium

“…3 In contrast, in a previous report, AF was termiKaplan-Meier event-free survival analysis was conducted to assess the cumulative freedom from AF recurrence using a cut-off of 43.5 mm for the LA diameter ( Figure 4B). The cumulative freedom from AF recurrence had a tendency to be greater in those with an LA diameter <43.5 mm than in those with an LA diameter ≥43.5 mm during 12±4.1 months of follow-up (65% vs. 42%; log-rank test, P=0.087).…”

“…As a predictor of successful termination of persistent AF, the measurement of the AF cycle length (CL) from the left atrial appendage (LAA) has been useful. 3 Further, as non-invasive pre-procedural predictors of the termination of persistent AF, the AFCL from the surface electrocardiogram (ECG) and duration of the continuous AF have been reported to be clinically useful as a pre-ablation tool for predicting the patients in whom SR can be restored by ablation. 5 Clinical prediction of the procedural and clinical outcomes of ablation in patients with persistent AF, however, have not been fully evaluated.…”

“…4 As a predictor of termination of persistent AF, the measurement of the AFCL from the LAA has been useful. 3 Further, as a pre-procedural non-invasive predictor of termination of persistent AF, the combined cut-off using a prolonged AFCL from the ECG and persistence of AF <2 years has been reported to be clinically useful as a pre-ablation prediction tool for identifying patients in whom SR can be restored by ablation. 5 It was a limitation of the previous study that it investigated only duration of continuous AF as a predictor.…”

Right Atrial Anatomical Remodeling Affects Early Outcomes of Nonvalvular Atrial Fibrillation After Radiofrequency Ablation

“…23, 24 In chronic AF, stepwise ablation of LA, including the pulmonary vein, roof line, CS, complex LA activities, and mitral isthmus, failed to terminate AF in 21% patients, suggesting that RA contributes, at least partially, to the maintenance of AF. 25 Meanwhile, Elayi et al reported that the bi-atrial ablation of a complex fragmented atrial electrogram has a minimal impact on AF termination during ablation. 26 However, the impact of the RA on the outcomes of AF after RFA is still controversial.…”

The Autonomic Nervous System and Atrial Fibrillation: The Roles of Pulmonary Vein Isolation and Ganglionated Plexi Ablation

“…In order to prevent such occurrences additional lesion sets were introduced: a left atrial roof line and a mitral isthmus line. More recently other procedures have been introduced as well, such as ablation of area showing CFAE and areas within the coronary sinus 31 or within the superior vena cava. 32 These additional lesion sets further increase the risk of gaps which in and of themselves provide channels that can allow macroreentrant atrial tachycardias or left atrial flutters to develop.…”