Ablation index-guided cavotricuspid isthmus ablation with contiguous lesions using fluoroscopy integrated 3D mapping in atrial flutter

Purpose The feasibility and safety of cavotricuspid isthmus (CTI) ablation with contiguous lesions using ablation index (AI) under the guidance of fluoroscopy integrated 3D mapping (CARTO UNIVU/CU) in typical atrial flutter (AFL) remains uncertain. This study aimed to determine the efficacy of AI-guided CTI ablation with contiguous lesions in patients with AFL. Methods In this single-center, prospective, non-randomized, single-arm, observational study, procedural outcomes were determined in 151 patients undergoing AI-guided CTI ablation (AI group) with a target AI value of 450 and an interlesion distance of <= 4 mm under CU guidance. These outcomes were compared with those of 30 patients undergoing non-AI-guided ablation (non-AI group). Results Among 151 patients, first-pass conduction block was achieved in 120 (80%) patients in the AI group (67% in the non-AI group, P = 0.152) with a shorter fluoroscopy time of 0.2 +/- 0.4 min (1.7 +/- 2.0 min in the non-AI group, P < 0.001). Conduction gaps were located at the atrial aspects near the inferior vena cava in 24 of 31 (78%) patients without first-pass conduction block. The AI group received 11 +/- 5 (12 +/- 4 in the non-AI group, P = 0.098) radiofrequency (RF) applications, and the RF time was 4.2 +/- 2.4 (5.1 +/- 2.5 min in the non-AI group, P = 0.011). Despite the occurrence of steam pop in 3 (2%) patients, none of them developed cardiac tamponade. No patients had recurrence within 6 months of follow-up. Conclusions AI-guided CTI ablation in combination with CU was feasible and effective in reducing radiation exposure in patients with AFL.