Is Tachycardia Termination during AF Substrate Ablation an Appropriate Ablation Endpoint in Longstanding, Persistent AF?

Abstract

Background: There are controversies regarding the endpoint of AF substrate ablation (AFSA) for longstanding, persistent AF (LPAF). We examined impacts of results of AFSA on post-ablation clinical outcomes. Methods and Results: Consecutive 240 patients with LPAF (AF duration: 80±97 months, LA diameter: 47±5 mm) underwent extensive PV isolation and AFSA with procedural endpoint of AF/atrial tachycardia (AT) termination. In all patients, bidirectional cavo-tricuspid isthmus block was created. Patients were classified into 5 groups according to the results of AFSA: Group-I: direct AF conversion into sinus rhythm (n=31); Group-II: AF conversion into common type atrial flutter (AFL) (n=18); Group-III: AF conversion into AT with subsequent AT termination (n=44); Group-IV: AF conversion into AT without subsequent AT termination (n=35); and Group-V: neither AF termination nor conversion into AT (n=112). During follow-up period of 333±218 days after the last session (1.5±0.7 sessions/patient), 87%, 89%, 80%, 69% and 62% of Groups-I-V patients, respectively, were free from AF/AT recurrences. Kaplan-Meier analyses revealed significant differences in AF/AT-free survival rates between Group-I vs. -V and Group-II vs. -V (P<0.01 for both). However, there were no significant differences in AF/AT-free survival rates between Group-III vs. -V, Group-IV vs. -V, and Group-III vs. -IV. Percentage of AT recurrence among the all AF/AT recurrences (75%, 0%, 78%, 100% and 28% in Groups-I-V, respectively) was significantly higher in Groups-III and -IV than in Group-V (Group-III vs. -V and Group-IV vs. -V: P<0.008). Conclusions: Those findings suggested that only AF conversion into AT or acute AT termination would not be an appropriate endpoint to prevent post-ablation AT recurrences. Creation of fixed conduction block across the AT circuit may be necessary to reduce the post-ablation AT recurrence.