The deeper the pouch is, the longer the radiofrequency duration and higher the radiofrequency energy needed-Cavotricuspid isthmus ablation using intracardiac echocardiography.

Background: The aim of this study was to explore whether the pouch depth influenced the radiofrequency (RF) duration and total delivered RF energy for cavotricuspid isthmus (CTI) ablation and define the cutoff value for a deep pouch-specified ablation strategy.

Methods: This study included 94 atrial fibrillation (AF) patients (56 males, age 68 ± 8.0 years). With intracardiac echocardiography, the isthmus length and pouch depth were precisely measured. After a standard AF ablation, all patients underwent the CTI ablation along the lateral isthmus. If bidirectional block could not be achieved, the ablation catheter was deflected more than 90 degrees to ablate inside the pouch (knuckle-curve ablation).

Results: Seventy-two patients (76.6%) had a sub-Eustachian pouch. Bidirectional block could be achieved in all patients. By a univariate logistic regression analysis, only the pouch depth was significantly correlated with the RF duration ( = .005) and RF energy ( = .006). A multivariate logistic regression analysis also revealed the pouch depth was the sole factor that influenced the RF duration ( = .001) and RF energy ( = .001). Among the 72 patients, 21 patients needed a knuckle-curve ablation. Using a receiver operating characteristic curve, the optimal cutoff value of the pouch depth for a knuckle-curve ablation was 3.7 mm with a sensitivity of 90% and specificity of 69%.

Conclusions: The sub-Eustachian pouch depth was the sole factor that influenced the RF duration and energy in the CTI ablation. If the pouch was deeper than 3.7 mm, a deep pouch-specified ablation strategy would be needed.