Relationship between the atrial‐activation pattern around the triangle of Koch and successful ablation sites in slow‐fast atrioventricular nodal reentrant tachycardia

The precise details of atrial activation around the triangle of Koch (ToK) remain unknown. We evaluated the relationship between the atrial‐activation pattern around the ToK and success sites for slow‐pathway (SP) modification ablation in slow‐fast atrioventricular reentrant tachycardia (AVNRT).Thirty patients with slow‐fast AVNRT who underwent successful ablation were enrolled. Atrial activation around the ToK during sinus rhythm was investigated using ultra‐high‐density mapping pre‐ablation. The relationships among features of atrial‐activation pattern and success sites were examined.Of 30 patients (22 cryoablation; 8 radiofrequency ablation), 26 patients had a collision site of two wavefronts of delayed atrial activation within ToK, indicating a success site. The activation‐search function of Lumipoint software, which highlights only atrial activation with a spatiotemporal consistency, showed non‐highlighted area on the tricuspid‐annulus side of ToK. In 23 of the patients, a spiky potential was recorded at that collision site outside the Lumipoint‐highlighted area. Fifteen cryoablation patients with a success site coincident with a collision site outside the Lumipoint‐highlighted area had significantly more frequent disappearances of SP after initial cryoablation (46.7% vs. 0%, p = .029), fewer cryoablations (3.7 ± 1.8 vs. 5.3 ± 1.3, p = .045), and shorter procedure times (170 ± 57 vs. 228 ± 91 min, p = .082) compared to the seven cryoablation patients without such sites. Four patients had transient AV block by ablation inside the Lumipoint‐highlighted area with fractionated signals, but no patient developed permanent AV block or recurrence post‐procedure (median follow‐up: 375 days).SP modification ablation at the collision site of atrial activation of the tricuspid‐annulus side along with a spiky potential could provide a better outcome.