Lesion size index-guided cavotricuspid isthmus linear ablation.

BACKGROUND: The lesion size index (LSI) predicts radiofrequency (RF) ablation lesion size and is an established parameter for pulmonary vein isolation. However, the effectiveness and safety of LSI for cavotricuspid isthmus (CTI) linear ablation remain unclear. METHODS: This single-center retrospective study included 50 of patients (67 ± 10 years, 68% male) who underwent de novo CTI linear ablation between July 2020 and December 2020. The LSI target was set at 5.0 and 4.0 for the anterior 2/3 and posterior 1/3 segments, respectively. Acute procedural parameters of ablation were evaluated. RESULTS: Acute bidirectional CTI block was achieved in all patients with an RF application time of 4.0 min (3.1-5.0 min), RF application number of 15 ± 7, and length of CTI of 36.9 ± 9.3 mm. First-pass bidirectional conduction block of the CTI was achieved in 39/50 (78%) patients. No major complications were observed. The contact force (CF) per application was significantly lower in the gap tag group than in the non-gap tag group (7 g [7-8 g] vs. 10 g [7-12 g], P = 0.0284). CONCLUSIONS: LSI-guided CTI linear ablation is an effective and safe treatment approach. CF affects gap formation, even when the target LSI is the same.