Mechanisms And Repeated Ablation Of Atrial Tachycardia After Catheter Ablation For Atrial Fibrillation

【Objective】Circumferential pulmonary vein isolation (CPVI) is the main ablation approach for atrial fibrillation, but may result in the prevalence of atrial tachycardia. The aim of this study was to determine the mechanisms of atrial tachycardia (AT) that occurs after ablation of atrial fibrillation (AF), to make clear the relation between AT postablation and procedure of AF, to analysis the outcome of ablation of AT, and to improve ablation technique and reduce the incidence of AT postablation.【Methods】One hundred and twenty-six patients [78 men, 48 women; mean age (59.51±11.08) years, range 35~82years] were included in this study. The mean history of AF of this study was (66.86±84.05) months, range from 7 days to 50 years. Of these cases,87 cases with paroxysmal AF and 39 cases with persistent AF underwent catheter ablation. These cases were divided into 3 groups, PVI group, CPVA group and persistent group. During a follow-up of 3 months to 2 years, 20 patients occurred AT after CPVA and underwent repeated catheter ablation. The mechnisms of these ATs were determined through activation mapping by Carto XP 3-dimensional maps or entrainment mapping. These ATs and its initial AF ablation were compared to make clear their relations.【Results】A total of 25 ATs were mapped, and the mechamism was micro-re-entry in 17 (68%) and focal in 8(32%). The critical isthmus in 16 (64%) traversed the prior ablation line, and 5 ATs (20%) originated from pulmonary vein. In PVI group of paroxysmal AF, 3 of the 4 ATs (75%) originated from pulmonary vein, consistent with a gap-related mechanism; 1 of the 4 ATs (25%) was micro-re-entry LA-AT. In CPVA group of paroxysmal AF , the mechanism was micro-re-entry in 12 of the 13 ATs(92.31%) and originating from SVC in 1 of the 13 ATs(7.69%); all of the re-entry ATs traversed the prior ablation line, consistent with a gap-related mechanism. In persistent AF group, 4 of the 8 ATs(50%) were micro-re-entry LA-ATs; 2 of the 8 ATs(25%) originated from pulmonary vein; the rest was focal ATs originated from other site. There was a low incidence of AT (5.56%) in those patients in whom AF was terminated during the initial procedure for persistent AF. The incidence rate of AT after CPVA in these 3 groups was no statistically difference through X2 test.【Conclusion】The prevalence of these arrhythmias may be reduced by demonstration of linear block, and pulmonary vein disconnection during the initial AF procedure. It may reduce AT after CPVA to reverse to sinus rhythm through radiofrequent ablation during the initial AF procedure for persistent AF. Repeat ablation may be effective and safety measure for ATs after catheter ablation.