Effect of Empirical Left Atrial Appendage Isolation on Long-term Procedure Outcome in Patients With Persistent or Long-standing Persistent Atrial Fibrillation Undergoing Catheter Ablation

Overview

The purpose of this prospective randomized study is to assess whether empirical Left Atrial Appendage (LAA) isolation along with the standard approach of pulmonary vein isolation (PVI) and ablation of extra-pulmonary triggers is superior to the standard approach alone in enhancing the long-term success rate of catheter ablation in persistent or long-standing persistent atrial fibrillation (AF) patients.

Persistent (PeAF) and long-standing persistent (LSP) AF are defined as sustained AFs extending beyond seven days and one year respectively (1). Hypertensive, ischemic, valvular and other structural heart diseases most commonly underlie these arrhythmias (2) and the resulting abnormal atrial substrate is believed to be the major contributor toward perpetuation of AF in these non-paroxysmal categories. Several studies have demonstrated that pulmonary vein isolation (PVI) by radiofrequency catheter ablation (RFCA) though successfully restores sinus rhythm in most patients with paroxysmal AF; it has limited success in these sustained arrhythmias (3). Presence of potential trigger-generating areas in the left and right atrium besides pulmonary veins, with reported incidence from 3.2% to 47% (4), can be held responsible for this limited success. These areas include superior vena cava, ligament of Marshall, crista terminalis, coronary sinus, left atrial (LA) posterior wall and LA appendage (3). Therefore, in order to enhance the procedural-success rate, various hybrid measures have emerged to target the PV as well as extra-PV areas that have the ability to initiate or maintain AF. Several previous studies have demonstrated the prevalence of LAA firing in patients with recurrence of AF/AT (atrial tachycardia) after catheter ablation of AF (4). Embryologically, LAA is the remnant of primitive LA, which is formed by the adsorption of primordial PV and their branches during 4th week of embryonic development. Therefore, it is logical to suggest that LAA may initiate AF like pulmonary veins. In an earlier study conducted by our group on 987 AF patients, LAA firing was revealed to be the source of AF in 27% of patients and 93% of those patients were arrhythmia free 6 months after LAA isolation (4). Our study aims to compare the procedure outcome for two different ablation strategies; 1) standard approach of pulmonary vein isolation extended to the posterior wall down to the coronary sinus and to the left side of the interatrial septum along with isolation of superior vena cava and ablation of complex fractionated atrial electrograms (CFAE) in the atria and coronary sinus, 2) standard approach plus LAA isolation. Hypothesis: LAA isolation combined with standard ablation procedure enhances the procedural success rate in non-paroxysmal AF patients undergoing catheter ablation.