**4. Predictive factors of AF recurrence after ablation**

Advances in ablation techniques have improved the prognosis for paroxysmal AF. However, the prognosis remains inadequate. To identify patients with a good prognosis, it is necessary to use a new index.

## **4.1 AF duration**

Our study [21] enrolled 82 consecutive patients (mean age, 65.0 ± 12.4 years), including 45 with persistent AF and 37 with long-standing persistent AF. The recurrence rate after ablation was high among patients with long-standing persistent AF. According to Watanabe et al. [22], compared with paroxysmal AF, persistent AF showed a higher recurrence rate after ablation but a lower rate of long-standing persistent AF. Generally, the longer the AF duration, the higher the AF recurrence rate.

## **4.2 Defibrillation threshold**

We studied postprocedural ablation predictors of AF recurrence after univariate and multivariate analyses in 82 patients.10 J was considered the average DFT for persistent AF and set as the cutoff value, as a review article [23] reported that the average DFT for intracardiac cardioversion (IC) of 25 patients with persistent AF was 9.1 ± 7.4 J. In patients with persistent AF, the AF recurrence rate increased with DFT for IC despite the addition of radiofrequency applications after PVI (such as box isolation). We demonstrated that the high DFT was the strongest prognostic factor for AF recurrence after the ablation procedure. Therefore, we speculate that the high DFT is correlated with atrial remodeling, which gradually decreases the success rate of catheter ablation in AF.
