Missing pouches in high‐density mapping of atrial tachyarrhythmia in congenital heart diseases

BACKGROUND: The use of high‐density electroanatomical mapping in the Chinese population for congenital heart disease (CHD) is not well reported. METHODS: Retrospective review of consecutive transcatheter ablation of atrial tachyarrhythmia using high‐density mapping for CHD patients (at least moderate complexity) in the only tertiary congenital heart center in the territory from January 2017 to January 2019 was conducted. Orion mapping catheter in Rhythmia system (Boston Scientific) was used to create activation and voltage maps. Parameters including mechanism of arrhythmia, acute success, and follow‐up data were recorded. RESULTS: Eight patients were identified (median age 35.5 years) who underwent transcatheter ablation of atrial arrhythmia. More than one reentry circuits of IART were identified in five patients. It took a median of 32.4 minutes with 15,952 (IQR 13,395‐18,530) mapping points per map. Cavo‐annulus isthmus‐dependent mechanism was the predominant reentry mechanism. Acute success with the elimination of all inducible tachycardia was achieved in six patients (75%), and partial success in two patients. There was recurrence of atrial arrhythmia in four patients (50%), in which three patients could be maintained in sinus rhythm with low‐dose antiarrhythmic medication. Targeted substrate ablation was performed in six patients with multiple IART circuits. Critical anatomical pouches were identified in three patients, which were missed in the initial mapping using Orion basket mapping catheter. CONCLUSIONS: High acute success rate of atrial arrhythmia ablation can be achieved using high‐density anatomical mapping in CHD. Substrate ablation was required with multiple IART circuits identified. Vigilance should be sought to identify anatomical pouches.