br Conflict of interest br Introduction

Conflict of interest
Introduction Catheter ablation is an effective approach for the management of patients with atrial fibrillation (AF) [1–7]. Pulmonary vein isolation (PVI) is one of the most common strategies of AF ablation, but the outcome of PVI alone for patients with persistent AF is poor [8–10]. Additional approaches such as linear ablation after PVI have been reported to improve the outcome [11–15]. Nademanee et al. also described an alternative approach for AF ablation that involved identifying the target “substrate” sites via electroanatomical mapping of complex fractionated atrial electrograms (CFAEs) [7–16,17]. Although PVI was not required with this orexin agonist approach, AF ablation guided by CFAEs resulted in a high rate of success in maintaining sinus rhythm in patients with either paroxysmal or persistent AF. However, the results of these studies were not replicated by others [6,18,19]. Thus, the role of CFAE-targeted catheter ablation (CFAE ablation) in treating patients with AF remains controversial. Because one of our physicians was a fellow at the Pacific Rim Electrophysiology Research Institute, all five physicians in our Institute similarly terminate AF with CFAE ablation [20,21]. In our latest study of 430 consecutive patients, AF was terminated by CFAE ablation with (n=133) or without (n=297) PVI in 97 (234/242) and 79% (149/188) of patients with paroxysmal and persistent AF, respectively, occasionally with nifekalant infusion without cardioversion. Thus, the use of optimal CFAE software settings on the CARTO3 may help physicians detect CFAE areas. Therefore, we determined the optimal setting of CFAE software on the CARTO3 system.
Materials and methods
Results We retrospectively analyzed 11,425 points during left atrial mapping before ablation and 10,306 points that were subjectively detected and ablated as CFAE points on CARTO3. We compared the default setting (default: 0.05–0.15mV, 50–120ms) and two modified settings according to a pilot study (#1: 0.05–0.30mV, 40–70ms, #2: 0.05–0.13mV, 10–20ms). We calculated the accuracy, sensitivity, specificity, positive productive value, and negative productive value for each setting. For the default setting, the accuracy, sensitivity, specificity, positive productive value, and negative productive value were 67, 42, 77, 48, and 73%, respectively. For modified setting #1, these values were 78, 55, 87, 74, and 77%, respectively, compared to 64, 82, 60, 53, and 91%, respectively, for modified setting #2 (Table 3). A comparison of each setting with the duration of AF is presented in Table 4, and a comparison between de novo and repeat sessions for each setting is presented in Table 5. Two example cases are shown in Figs. 2 and 3. These data suggested that setting #1 is the optimal setting in general, whereas setting #2 was optimal for excluding areas that do not require ablation.
Discussion There are several types of electrograms that we consider CFAEs. In the original study [7], two types of electrograms were mentioned as CFAEs: 1) fractionated electrograms composed of two or more deflections and/or a perturbation of the baseline with continuous deflection of a prolonged activation complex; and 2) atrial electrograms with an extremely short cycle length (≤120ms). The software attempted to cover both types of electrograms, requiring a wider interval setting. Most electrograms requiring ablation are continuous and more fractionated, for which a shorter interval setting may be better in general.
Limitation
Conclusions The optimal settings of CFAE software on CARTO3 system were a voltage range of 0.05–0.30mV and an interval range of 40–70ms.
Sources of funding This study was supported by Fukuda Foundation for Medical Technology of Japan.
Conflict of interest
Acknowledgments
Introduction Catheter ablation (CA) is a treatment option for patients with atrial fibrillation (AF). However, interventional AF treatment has been associated with dangerous complications such as atrio-esophageal fistula [1–3]. The mechanism most likely leading to atrio-esophageal fistula after radiofrequency (RF) ablation is thermal esophageal injury during the ablation procedure [4,5]. The incidence of esophageal injury after RF ablation of AF has been reported to range from 5% to 50% depending on the RF power settings and ablation strategies [6–8]. To avoid this complication, esophageal temperature probes, inserted nasally and advanced to the level of the left atrium (LA) under fluoroscopic guidance, are used to mark the location of the esophageal lumen and permit real-time intraluminal esophageal temperature monitoring (ETM) during ablation [9–11]. Furthermore, body mass index (BMI) has been reported to be a predictor of esophageal injury, indicating that patients with a lower BMI (<24.9) are at a higher risk [12]. However, the incidence of esophageal injury in patients with a low BMI has not been well scrutinized.