High efficacy of the multifaceted strategy for persistent atrial fibrillation

Abstract

Summary Catheter ablation of persistent atrial fibrillation (AF) is challenging and needs a combination of different techniques targeting a wider substrate to be effective. The so-called stepwise approach progressively targets structures potentially contributing to initiation and maintenance of AF. The endpoints of the procedure consist of pulmonary vein isolation, organisation and slowing of left and right atrial electrograms and linear block in the left atrial (LA) roof and mitral isthmus lines. This strategy results both in high rate of AF termination (85%) and an unprecedented clinical outcome. Electrogram-based ablation is crucial for the procedural outcome. While continuous and fractionated electrograms are targeted during complex atrial activity, more discrete sites like temporal activation gradient, rapid or centrifugal activity are ablated when atrial activity is organised allowing discrete mapping. AF cycle length (CL) measured in both appendages has been demonstrated to be the strongest independent predictor of procedural AF termination in AF lasting 140 ms predicts AF termination of more than 89%. AFCL also allows monitoring impact of each step of catheter ablation. LA ablation is usually associated with prolongation of both LA appendage (LAA) CL and right atrial appendage (RAA) CL, while prolongation of LAA CL without concomitant significant prolongation in RA suggests the presence of drivers in RA, requiring additional RA ablation. Because AF recurrence after the first procedure occurred in only 5% of the cases when AF terminated during the procedure vs 45% if AF persisted, AF termination represents an incontrovertible endpoint of the ablation process. The mode of termination of persistent AF is conversion to multiples atrial tachycardia (AT) in the vast majority of cases. Mapping and ablation of those have become indispensable steps in the ablation process. Predominant ATs are localised re-entries requiring mapping of local activity spanning most of the AT cycle length in the area of earliest activity. In conclusion, catheter ablation of persistent AF requires isolation of all PV electrogram based ablation and linear lesions in the majority of patients. AF CL is an important guide for monitoring progress of ablation and reliably predicts the procedural outcome. AF termination by ablation is associated with excellent outcome. Mapping and ablation of subsequent atrial tachycardias are an integral part of the AF ablation process and its success often makes the difference between cure and persistent illness.