Direct comparison of clinical outcome between linear and EGM (CFAE)-guided ablation
Although previous meta-analyses comparing different strategies for PsAF ablation in the different cohorts reported non-superiority of additional substrate modification beyond PVI, the studies were associated with heterogenous patient populations and follow-up periods.9,21 Only two previous studies have prospectively compared linear ablation and CFAE ablation in PsAF patients. In contrast to our results, both studies reported no significant differences in arrhythmia-free survival between the two groups during medium-term follow-up.11,12 While Estner et al. reported similar outcomes between linear ablation and CFAE ablation at 1 year, the success rates were lower than those in the present study (linear vs. CFAE: 37% vs. 39%) despite high success rates of linear block (100%) and AF termination (82%) during CFAE ablation. Of note, their ablation strategy in the linear ablation group included roof and anterior lines in only two thirds of patients, and mean LA size was larger (47-49 mm).12 These results may suggest that the effect of linear ablation, especially anterior line ablation, is limited in advanced PsAF. In the STAR-AFII trial, there was no difference in AF/AT-free survival between linear ablation (roof and MI lines) and CFAE ablation during 1.5 years of follow-up (41% vs. 37%). Regarding procedural results, AF terminated in 45% by CFAE ablation, and successful linear ablation was achieved in 93% and 75% of roof and MI lines, respectively.11 There are a number of potential explanations for the inconsistent results between our study and STAR AF II. Firstly, the acute success rate of MI line block was relatively lower than our study (81%). Secondly, our ablation protocol included ablation for non-PV foci. Thirdly, we confirmed elimination of dormant conduction post-PVI with isoproterenol and adenosine after 30 minutes waiting in all patients. Fourthly, a steerable sheath was used for linear ablation, which may have contributed to the higher successful rate in the linear ablation group.33 Overall, our study showed consistent efficacy of linear ablation in PsAF patients during very long-term follow-up (>8 years) after the initial and multiple catheter ablation procedures with fewer procedures compared to the EGM-guided ablation cohort. Multiple ATs was more frequently induced at the re-do procedure in the EGM-guided ablation group. These findings may suggest that some of the critical CFAE areas were not targeted during the index ablation,15,32 and potential incompletely ablated areas may create a substrate for iatrogenic arrhythmias.34