Abstract 2098: Electrogram-guided Substrate Ablation in paroxysmal and persistent Atrial Fibrillation: Spatial Distribution of Preferential Sites of Ablation leading to Termination or Organization of Atrial Fibrillation

Background: Modification of the substrate maintaining atrial fibrillation (AF) can be achieved by ablation of complex fractionated atrial electrograms (CFAE). However, there is little information about preferential ablation sites in the left (LA) and right atrium (RA) in which organization or termination of AF occurs. Methods: In 66 patients (P, 60 ± 9 years, 48 male) with paroxysmal (36 P) or persistent AF (30 P), areas showing CFAE during AF were ablated in the LA (all P) and RA (35 P). The LA and RA were divided into 6 and 3 segments respectively. In the LA the left (1) and right (2) pulmonary veins (PV), the roof (3), the septum (4), anterior wall with the left atrial appendage (LAA; 5) and the posterior mitral annulus (MA; 6); in the RA, the coronary sinus (CS; 1), superior vena cava (SVC; 2) and crista terminalis (3). Termination of AF (in persistent AF) or non-inducibility of AF (in paroxysmal AF) was the procedural endpoint. Results: AF stopped or was no longer inducible in 19/36P (53%) with paroxysmal and 9/30P (30%) with persistent AF. Additionally, regularization of AF or termination with inducibility was achieved in 13/36 P (36%) with paroxysmal and 15/30 P (50%) with persistent AF. Termination of AF was observed in 53 localizations (more than one termination site per P possible). The most frequent AF termination site in both groups was the anterior LA/LAA (14/53; 26%), followed by the left PV (9/53; 17%), the septum (8/53; 15%), posterior MA (7x), right PV (6x), LA roof (4x), CS (4x) and SVC (1x). One pericardial effusion was drained by pericardiocentesis and one PV stenosis was treated acutely by direct stenting. Conclusion: The ablation of complex fractionated electrograms results in termination or regularization of AF in approximately 80% of patients with paroxysmal or persistent AF. In both groups, preferential AF termination site was the anterior wall of the LA/base of left atrial appendage. These results may imply consequences for the preferential ablation targets in electrogram-guided AF ablation.