Introduction
Radiofrequency catheter ablation (RFCA) has been shown to be more efficacious than drug therapy in restoring sinus rhythm (SR) in patients with atrial fibrillation (AF). Compared to the other ablation strategies, pulmonary vein isolation (PVI) is a more basic strategy.1 Furthermore, a trigger ablation is one of the strategies for AF ablation, which is effective for eliminating AF.2 Isoproterenol (ISP) is often used to induce AF triggers.3 In addition, defibrillation of induced AF is performed to identify the site of the trigger of spontaneously occurring AF. In those procedures, intracardiac defibrillation (IDF) is often performed to restore SR during RFCA of AF.4
There have been many studies about cardioversion of AF, such as regarding the relationship between the defibrillation threshold and maintaining SR in patients without RFCA.5-11 On the other hand, many other studies have pointed out the relationship between AF recurrence after RFCA and the substrate, such as the left atrium (LA) size and low voltage zones (LVZs). However, a few studies have shown the relationship between the IDF threshold and recurrence of AF after RFCA. Furthermore, there have been no studies to assess the relationship between the IDF and LA substrate. This study aimed to examine the change in the IDF threshold before and after RFCA for eliminating persistent AF during the procedure. Additionally, we evaluated whether the IDF threshold after RFCA was associated with the recurrence of AF and the AF substrate after the ablation procedure in patients with persistent AF.