1320Effectiveness of atrial flutter ablation line selection using SOUNDSTAR catheter
Abstract Background Cavotricuspid isthmus (CTI) ablation for atrial flutter (AFL) shows a high success rate and effective for patients. However, operators experience difficulties in CTI ablation in some cases and need additional ablation for repeated recurrence. We investigated whether the SOUNDSTAR® (Biosense. Webster, Diamond Barr, CA, USA) catheter would be effective to select a CTI line of high therapeutic effect. Methods We have investigated the anatomy of around CTI by SOUNDSTAR® catheter and decided the CTI line using the anatomical information in AFL ablation (Figure1). We assumed two CTI lines of medial and lateral line. Medial CTI (M-CTI) line was more common and shorter line. Lateral CTI (L-CTI) line was uncommon and slightly longer line. We use 3.5mm tip catheter with NxT steerable introducer. The target Ablation Index (AI) was 400, and the target VisTtag™ interval was 6 mm or less. Results A total 30 of AFL ablated cases were investigated retrospectively. We surveyed 15 cases in M-CTI group and 15 cases in L-CTI group. Comparing the length of CTI in all cases, the length of M-CTI line was shorter than L-CTI line (M-CTI 32.1 ± 6.6mm vs. L-CTI 38.4 ± 8.3mm, n = 30, p <0.01). The atrial wall thickness of midsection and tricuspid valve (TV) side were thicker in M-CTI line (Midsection: M-CTI 4.0 ± 1.2mm vs. L-CTI 3.3 ± 0.8mm, n = 30, p <0.05, TV side: M-CTI 5.4 ± 1.4mm vs. L-CTI 4.3 ± 1.1mm, n = 30, p <0.05,). There was no difference in the required number of points to complete initial line (M-CTI 8.4 ± 1.6 vs. L-CTI 8.1 ± 1.7, n = 15, ns). Eustachian ridge in IVC side was thicker and higher in the M-CTI group (3.4 ± 3.3mm vs. 0.9 ± 1.9mm, n =30, p <0.01) and ablation on the Eustachian ridge showed instability of catheter placement. A lot of RF delivery was required on Eustachian ridge in M-CTI (2.6 ± 0.6 vs. 2.1 ± 0.7, n =15, p <0.05) and AI had resulted lower in M-CTI (351 ± 42.8 vs. 381 ± 27.1, n =15, p <0.05). Recurrence is more common in M-CTI group (9/15, 60% vs. 3/15, 20%). Recurrence sites in M-CTI group were distributed ((IVC side 3/9 (33%), midsection 5/9 (56%), TV side 5/9 (56%)) and multiple recurrences occurred in 3/9 (33%). Recurrence sites in L-CTI were only midsection of CTI (3/3, 100%). Conclusions CTI ablation at the shorter distance M-CTI, which is commonly selected, resulted in more recurrences due to the unevenness including Eustachian ridge and the myocardium thickness. However, ablation at slightly longer L-CTI line showed lower recurrence and effective for CTI ablation. Abstract Figure 1