AF termination and rhythm outcome
The importance of AF termination as a procedural endpoint that correlates positively with rhythm outcome is still in debate. AF termed in 51% of catheter ablation using a sequential biatrial linear defragmentation approach. Miyazaki et al. reported that AF termination was the sole factor predicting freedom from both arrhythmia recurrence and crossover to rate control strategies during long-term follow-up.2 While, in the subgroup analysis of STAR AF II, AF termed in 8% of the PVI, 45% in the PVI plus CFAE ablation and 22% of the PVI plus linear ablation and the AF termination could not predict the better rhythm outcome.4 This discrepancy might be caused by 1) multiple procedure or single procedure, 2) follow-up period (60 months vs. 18 months). CFAE ablation was associated with a high likelihood of AT as the mode of arrhythmia recurrence. Actually, linear ablation was mainly performed for macro-reentrant ATs in the 2nd procedure. Of note, the AF recurrence was significantly less after eliminating AT after index procedure when 2nd or 3rd session was mainly performed from 4 to 28 months after the initial procedure. In our study, the mode of the arrhythmia recurrence was perimitral AT in one patient with a favorable response. Thus, no AF recurrence was found in patients with a favorable response. We speculated that AF termination during RF application could reduce the AF recurrence, however, additional RF application could have a potential risk of increasing the AT substrate. The PLS ablation provide the relatively high AF termination and the excellent outcome, however, the ablation target area should have been more specifically focused and we should have used the time for creating a durable PVI and linear lesion. Recently, Ashihara et al. had developed a novel online real-time phase mapping system: ExTRa Mapping.13 By using this novel system, we reported the case in which RF application at the AF rotor area overlapped with the PLS could convert AF to common atrial flutter.21 We would like to hope that this real-time mapping system and LGE-MRI assessment could make it possible to intervention on the specific AF substrate.