Different Time Course of Early Recurrence and Significance for Late Recurrence
A previous study has suggested that the incidence of ER decreases after 1-month post-ablation, in accordance with the normalization of the systemic inflammatory response as assessed by WBC and CRP levels.13 Histological examinations after RF delivery have demonstrated that myocardial tissue conversion to fibrotic and fatty tissue is not completed within 1 month, as macrophages and lymphocytes are still present in the ablation lesion for 4–8 weeks after ablation.14 Thus, local tissue inflammation may persist after 1 month. In the present study, the greatest number of patients experienced ER in the 1stmonth after PAF ablation, and ER occurrence decreased in the 2nd and even more in the 3rd month, in both groups. A decrease in the inflammatory changes can explain the time-dependent decrease in the incidence of ER. However, the timing of the last ER for most patients in the Non-CF group was the 3rd month, whereas it was the 1stmonth in the CF group. Lower initial inflammatory changes in the CF group may result in earlier disappearance of inflammatory changes. Furthermore, 78% of patients in the Non-CF group with ER in the 3rd month developed LR, whereas 100% of patients in the CF group with ER in the 3rd month developed LR. Therefore, recurrence in the 3rd month may be due to residual triggers, including reconnection of the PVI lesion, in the CF group. With CF technology, the blanking period can be defined as the first 2-month period, and patients with ER in the 3rdmonth can be good candidates for an early redo-procedure. In addition, reconnection of the PV after the 2nd procedure was less frequent in patients who undergo an AI-based ablation than in those who undergo an FTI-based ablation in the CF group, suggesting that AI-based ablation ensures more durable PVI than FTI-based or non-CF catheter-based PVI.