Efficacy of three-dimensional electroanatomic mapping-guided minimally invasive transaxillary atrial appendage resection for focal atrial tachycardia originating from the atrial appendage in children

Objectives To investigate the clinical characteristics and short-to-medium-term outcomes of minimally invasive transaxillary atrial appendage resection guided by the Carto3 three-dimensional electroanatomic mapping system for focal atrial tachycardia originating from the atrial appendage (atrial appendage tachycardia, AAT) in children. Methods This single-center retrospective study consecutively enrolled 27 children with atrial tachycardia (AT) who underwent Carto3-guided electrophysiologic study between January 2023 and April 2026; 6 (22.2%) were confirmed to have AAT. Treatment was individualized according to anatomical origin: minimally invasive transaxillary appendage resection for appendage tip origin or aneurysm ( n = 5) and pulsed field ablation (PFA) for appendage base origin ( n = 1). The results for the two groups are reported separately. Results All six patients (four male, 66.7%; mean age 10.28 ± 3.49 years) showed Carto3 activation patterns suggestive of focal origin. The earliest activation was at the appendage tip in 5 (83.3%) and at the base in 1 (16.7%); 5 (83.3%) had incessant AT; and 3 (50%) had tachycardia-induced cardiomyopathy (TIC). Appendage resection group ( n = 5): All patients achieved immediate AT termination and sinus rhythm restoration. At a median follow-up of 13 months (IQR 6.75–16.25; minimum 6 months), no recurrence or procedure-related complications were observed. Given the very small sample size and limited follow-up, these preliminary findings should not be considered confirmatory evidence of safety and efficacy. PFA group ( n = 1): Immediate success was achieved, but AT recurred at 1 month post-procedure (Holter-confirmed); the patient is currently being managed medically. In the three patients with TIC, LVEF improved from 46.3 ± 8.3% to 62.0 ± 6.1% and FS from 23.3 ± 4.8% to 33.3 ± 4.6% at the final follow-up, showing a descriptive improving trend; LVEDd decreased from 47.3 ± 3.5 mm to 42.0 ± 5.3 mm. Given n = 3, these results are presented descriptively, without inferential interpretation. Conclusions In this small preliminary series, one-stop minimally invasive transaxillary appendage resection showed initial feasibility and favorable short-term outcomes in pediatric AAT with Carto3-confirmed appendage tip origin or associated aneurysm refractory to medical therapy. TIC secondary to AAT may be reversible after arrhythmia elimination. These preliminary findings require validation in larger, multicenter, prospective studies. The role of PFA in pediatric AAT warrants further investigation.