INTRODUCTION: The suitability of high-power short-duration (HPSD) cavo-tricuspid isthmus ablation (CTI-Abl) for electrophysiology (EP) trainees, as well as the underlying mechanisms of its efficacy, remain unknown. The aim of this study was to clarify the efficacy and safety of HPSD CTI-Abl performed by EP trainees and assess lesion characteristics between HPSD and moderate-power long duration (MPLD) ablations. METHODS: Study 1: CTI-Abl was performed by first- to fourth-year EP trainees in consecutive 113 patients (67 ± 11 years, 27.2% female). Study cohort was historically divided into three groups: MPLD (30-35 W for up to 30 s) using TactiCath (TC-MPLD, N = 38) and MPLD and HPSD (50 W for 12 s) using TactiFlex (TF-MPLD, N = 23
TF-HPSD, N = 52). Primary endpoint was first-pass bidirectional isthmus block (BIB). Study 2: lesion geometries created by each ablation strategy were compared using an ex-vivo model. RESULTS: Study 1: TF-HPSD ablation strategy demonstrated a higher success rate of first-pass BIB than MPLD protocol (TC-MPLD, 58%
TF-MPLD, 48%
TF-HPSD, 94%, p <
0.001), without any complications. TF-HPSD group was associated with shorter total procedure and RF application times, as well as fewer ablation points and gaps, compared to the MPLD groups. Study 2: TF-HPSD created greater lesion surface length, width, and area than MPLD strategies. CONCLUSION: HPSD CTI-Abl performed by EP trainees using TactiFlex SE catheter demonstrated a higher first-pass BIB rate, shorter total procedure and RF application times, and fewer ablation points and gaps compared to the conventional method, without increasing complication rates.