Abstract 14874: Electrical Isolation of the Posterior Left Atrium is Associated With a Lower Incidence of Atrial Tachycardia in Patients With Persistent Atrial Fibrillation

Introduction: Patients may develop atrial tachycardia (AT) after left atrial (LA) ablation of persistent atrial fibrillation (AF). Hypothesis: We hypothesized that patients with persistent AF undergoing electrical isolation of the posterior wall of the LA would be less likely to experience AT, and specifically, roof-dependent tachycardia as compared to historical controls who only received linear ablation at the LA roof. Methods: The population consisted of 101 consecutive patients (age= 64.3±8.7 years, 70 males (69%), LA=4.6±0.8 cm, ejection fraction=48.5±16%) undergoing their initial procedure for persistent AF. After pulmonary vein isolation, patients either underwent posterior LA isolation (n=50; study group) or linear ablation at the LA roof with verification of conduction block by established pacing maneuvers (n=51; control group) Results: During the initial procedure for AF, electrical isolation of the posterior LA or linear block at the LA roof were achieved in all patients in the study or control groups, respectively. During follow-up, patients in the study group were less likely to develop AT (9/50 [18%] vs. 18/51 [35%]; p=0.02), roof-dependent (1/50 [2%] vs. 8/51 [16%]; p=0.008), and multi-loop AT (6/50 [12%] vs. 14/51 [27%]; p=0.03) as compared to controls. A repeat procedure was performed in 18 (34%) and 28 (55%) patients in the study and control groups, respectively (p=0.03). After a mean follow-up of 25.3 ± 13, and 50.3 ± 27.3 months, 45 of the 50 study (90%), and 44 of the 51 control patients (86%) remained in sinus rhythm (p=0.72), with 12 and 13 patients taking antiarrhythmic medications, respectively (p=0.43) Conclusions: In patients with persistent AF, posterior LA isolation is associated with a lower risk of a redo procedure, roof-dependent macro-reentry, and post-ablation AT in general as compared to controls who only received linear ablation of the left atrial roof. Posterior LA isolation also obviates pacing maneuvers, the results of which might be equivocal, and may be a more definitive endpoint of linear ablation at the LA roof