Background and Objectives: Cavotricuspid isthmus (CTI) block is easily achieved, and prophylactic ablation can be performed during atrial fibrillation (AF) ablation. However, the previous study was too small and short-term to clarify the efficacy of this block. Methods: Patients who underwent catheter ablation for paroxysmal AF were enrolled, and patients who had previous or induced atrial flutter (AFL) were excluded. We randomly assigned 366 patients to pulmonary vein isolation (PVI) only and prophylactic CTI ablation (PVI vs. PVI+CTI). Results: There was no significant difference in procedure time between the two groups because most CTI blocks were performed during the waiting time after the PVI (176.8±72.6 minutes in PVI vs. 174.2±76.5 minutes in PVI+CTI, p=0.75). All patients were followed up for at least 18 months, and the median follow-up was 3.4 years. The recurrence rate of AF or AFL was not different in the 2 groups (25.7% in PVI vs. 25.7% in PVI+CTI, p=0.92). The recurrence rate of any AFL was not significantly different in the 2 groups (3.3% in PVI vs. 1.6% in PVI+CTI, p=0.31). The recurrence rate of typical AFL also was not different (0.5% in PVI vs. 0.5% in PVI+CTI, p=0.99). Conclusions In this large and long-term follow-up study, prophylactic CTI ablation had no benefit in patients with paroxysmal AF without typical AFL.

Background and Objectives: Cavotricuspid isthmus (CTI) block is easily achieved, and prophylactic ablation can be performed during atrial fibrillation (AF) ablation. However, the previous study was too small and short-term to clarify the efficacy of this block. Methods: Patients who underwent catheter ablation for paroxysmal AF were enrolled, and patients who had previous or induced atrial flutter (AFL) were excluded. We randomly assigned 366 patients to pulmonary vein isolation (PVI) only and prophylactic CTI ablation (PVI vs. PVI+CTI). Results: There was no significant difference in procedure time between the two groups because most CTI blocks were performed during the waiting time after the PVI (176.8±72.6 minutes in PVI vs. 174.2±76.5 minutes in PVI+CTI, p=0.75). All patients were followed up for at least 18 months, and the median follow-up was 3.4 years. The recurrence rate of AF or AFL was not different in the 2 groups (25.7% in PVI vs. 25.7% in PVI+CTI, p=0.92). The recurrence rate of any AFL was not significantly different in the 2 groups (3.3% in PVI vs. 1.6% in PVI+CTI, p=0.31). The recurrence rate of typical AFL also was not different (0.5% in PVI vs. 0.5% in PVI+CTI, p=0.99). Conclusions In this large and long-term follow-up study, prophylactic CTI ablation had no benefit in patients with paroxysmal AF without typical AFL.

Background and Objectives: The efficacy of radiofrequency catheter ablation (RFCA) in atrial fibrillation (AF) is well established. The standard approach to RFCA in AF is pulmonary vein isolation (PVI). However, a large proportion of patients experiences recurrence of atrial tachyarrhythmia. The purpose of this study is to find out whether the AI model can assess AF recurrence in patients who underwent PVI. Materials and methods: This study was a retrospective cohort study that enrolled consecutive patients who under‑ went catheter ablation for symptomatic, drug-refractory AF and PVI. We developed an AI algorithm to predict recur‑ rence of AF after PVI using patient demographics and three-dimensional (3D) reconstructed left atrium (LA) images. Results: We included 527 consecutive patients in the study. The overall mean LA diameter was 42.0 ± 6.8 mm, and the mean LA volume calculated using 3D reconstructed images was 151.1 ± 46.7 ml. During the follow-up period, atrial tachyarrhythmia recurred in 158 patients. The area under the curve (AUC) of the AI model based on a convolu‑ tional neural network (including 3D reconstruction images) was 0.61 (95% confidence interval [CI] 0.53–0.74) using the test dataset. The total test accuracy was 66.3% (57.0–75.6), and the sensitivity was 53.3% (34.8–71.9). The specificity was 73.2% (51.8–75.0), and the F1 score was 52.5% 34.5–66.7). Conclusion In this study, we developed an AI algorithm to predict recurrence of AF after catheter ablation of PVI using individual reconstructed LA images. This AI model was unable to predict recurrence of AF overwhelmingly;therefore, further large-scale study is needed.

Background and Objectives: Atrial tachycardias (ATs) from noncoronary aortic cusp (NCC) uncovered after radiofrequency ablation for atrial fibrillation (AF) are rarely reported. This study was conducted to investigate the prevalence and clinical characteristics of NCC ATs detected during AF ablation and compare their characteristics with de novo NCC ATs without AF. Methods: Consecutive patients who underwent radiofrequency catheter ablation for AF were reviewed from the multicenter AF ablation registry of 11 tertiary hospitals. The clinical and electrophysiological characteristics of NCC AT newly detected during AF ablation were compared with its comparators (de novo NCC AT ablation cases without AF). Results: Among 10,178 AF cases, including 1,301 redo ablation cases, 8 (0.08%) NCC AT cases were discovered after pulmonary vein isolation (PVI; 0.07% in first ablation and 0.15% in redo ablation cases). All ATs were reproducibly inducible spontaneously or with programmed atrial stimulation without isoproterenol infusion. The P-wave morphological features of tachycardia were variable depending on the case, and most cases exhibited 1:1 atrioventricular conduction. AF recurrence rate after PVI and NCC AT successful ablation was 12.5% (1 of 8). Tachycardia cycle length was shorter than that of 17 de novo ATs from NCC (303 versus 378, p=0.012). No AV block occurred during and after successful AT ablation. Conclusions Uncommon NCC ATs (0.08% in AF ablation cases) uncovered after PVI, showing different characteristics compared to de-novo NCC ATs, should be suspected irrespective of P-wave morphologies when AT shows broad propagation from the anterior interatrial septum.