Linear ablation for persistent atrial fibrillation: an evidence-based study

Background Additional linear ablation for persistent atrial fibrillation (PerAF) still has limited evidence-based medical proof. Objectives We probed into the mechanisms of intermediate atrial tachycardia (AT) during PerAF termination by catheter ablation and provided evidence for it. Methods 136 patients who converted to organized AT after PerAF termination in the Extent-AF study were analyzed. Bi-atrial activation mapping combined with entrainment mapping were performed to identify the mechanisms and critical isthmus of these ATs. Results A total of 164 ATs in 136 patients were identified (average 1.2 per patients) and 143 (87%) ATs in 113 patients (average 1.3 per patient) were successfully mapped. The mechanisms of intermediate ATs were macro-reentry in 110 (77%), micro-reentry in 21 (15%), and focal AT in 12 (8%). Among the macro-reentrant ATs, the most common were perimitral ATs (PM-AT) 52 (47%), followed by roof dependent ATs (RF-AT) in 40 (36%) and typical atrial flutter (AFL) in 18 (16%). 98 (72%) patients had successfully ablated intermediate ATs. Among these patients, 88 (90%) required at least one of the perimitral line, roofline, or peritricuspid line to finally restore sinus rhythm. At the end of 12 months of follow-up, 63 (64.3%) patients with successful ablative ATs were free of any arrhythmia. Conclusion The majority of intermediate ATs after PerAF termination were macro-reentrant ATs. Linear ablation targets the mitral isthmus, roof, and tricuspid isthmus was a critical step of PerAF ablation to restore sinus rhythm in up to 90% patients, suggesting the importance of additional linear ablation. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial chictr.org.cn; Optimization of intervention strategies for persistent atrial fibrillation; ChiCTR2200060075. ### Funding Statement This research was supported by Grants from the National Natural Science Foundation of China (No. 82370355) and the National Key Research and Development Project (Grant Number 2018YFC1312503). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Not Applicable The details of the IRB/oversight body that provided approval or exemption for the research described are given below: ethics committee of Shanghai Chest Hospital I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Not Applicable I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Not Applicable I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Not Applicable The data underlying this article will be shared on a reasonable request to the corresponding author.