Clinical significance of induced atrial tachycardia observed during repeat catheter ablation for atrial tachyarrhythmia

Abstract Background Pulmonary vein isolation (PVI) is an effective and established treatment for atrial fibrillation (AF). However, atrial tachycardia (AT) occurring after the initial catheter ablation (CA) for AF remains a significant clinical challenge. In particular, the efficacy of ablation for induced AT during the procedure has not been well known. Purpose This study aimed to investigate the characteristics of induced AT and to evaluate the efficacy of ablation for induced AT. Methods We retrospectively analyzed patients who underwent the second CA for atrial tachyarrhythmia between April 2021 and March 2024 across nine institutions in Japan. Of these, patients who required ablation for AT that occurred during the second CA were extracted. Thereafter, the patients were divided into two groups; induced AT group (patients in whom AT was induced by burst pacing) and spontaneous AT group (patients in whom AT sustained from the beginning of the procedure or occurred spontaneously without induction). The type of AT and the three-year recurrence of AF or AT after the second CA were evaluated between the two groups. Results Among 864 cases of the second CA for atrial tachyarrhythmia, 311 patients who underwent ablation for AT that occurred during the procedure were included in this study (Figure 1). Induced AT group comprised 154 patients, and spontaneous AT group comprised 157 patients. During a median follow-up period of 666 days, the three-year rate of AF/AT recurrence was significantly higher in the induced AT group than in the spontaneous AT group (54% vs. 32%, P = 0.032). Specifically, AT recurrence was significantly more frequent in the induced AT group (41% vs. 20%, P = 0.017), whereas there was no significant difference in AF recurrence between the two groups (20% vs. 16%, P = 0.70) (Figure 2). On multivariate analysis, induced AT was identified as an independent predictor of AT/AF recurrence (hazard ratio 1.54, 95% CI 1.02–2.32, P = 0.039). Cavotricuspid isthmus (CTI)–dependent flutter was more frequently observed in the spontaneous AT group (16.5% vs. 7.1%, P = 0.009), whereas right atrial (RA) reentrant AT other than CTI-dependent flutter and RA focal AT were more frequent in the induced AT group (RA reentrant AT 5.7% vs. 13.6%, P = 0.02, RA focal AT 4.4% vs. 14.3%, P = 0.002). In contrast, there were no significant differences between the two groups in the frequency of peri-mitral AT or left atrial roof AT. Conclusion Ablation for induced AT may be less effective than that for spontaneous AT. Therefore, the indication for ablation of induced AT requires more careful consideration compared with that for spontaneous AT.Figure 1Figure 2