Cavotricuspid isthmus ablation using ablation index in typical right atrial flutter

Abstract

Background Ablation index (AI) has been evaluated as guidance quality marker for pulmonary vein isolation, but not for linear ablation of the cavotricuspid isthmus (CTI) for typical right atrial flutter (AFL). We thus studied the feasibility and effectiveness of AI‐guided CTI for AFL. Methods Procedural and 6‐month outcomes of ablation for AFL were retrospectively compared between consecutive patients undergoing either AI‐guided ablation of CTI (n = 43; AI target of 500 for anterior 2/3 segments and 400 for posterior 1/3 segments) or contact force (CF)‐guided ablation (n = 42) at a single center. Each Visitag dataset from all patients in each group was analyzed. Results AI guidance vs CF guidance was associated with: higher first‐pass conduction block of CTI (93.0% vs 76.2%, P = .03) with similar ablation time; similar acute spontaneous CTI reconnection 2.3% vs 9.5%, P = .343); fewer radiofrequency (RF) applications (10.1 ± 2.8 vs 11.5 ± 3.0, P = .031) needed to achieve CTI directional block; significantly higher mean ablation time, impedance drop, force time integral and AI and similar mean CF and power of each VisiTag point. One inguinal hematoma and one pseudoaneurysm developed in the AI and CF groups, respectively. Recurrent AFL was recorded in two (4.7%) AI‐group patients and four (9.5%) CF‐group patients (P = .650). Conclusion AI‐guided ablation of CTI line for AFL appears feasible and effective with similar ablation time, fewer RF applications, a higher rate of first‐pass conduction block, and no additional complications.

Optimal local impedance drops for an effective radiofrequency ablation during cavo‐tricuspid isthmus ablation

“…1,2 The endpoint of the CTI linear ablation is to achieve bidirectional conduction block along the CTI. 3 A CTI linear ablation generally has a high success rate, and several parameters during the ablation have been reported to further facilitate the achievement of bidirectional conduction block: contact force (CF), 4,5 force-time integral (FTI), 6 Ablation Index (AI) incorporating the CF, RF application duration, and power in a weighted formula, 7 and the electroanatomic coupling index. 8 A novel ablation catheter capable of local impedance (LI) monitoring (IntellaNav MiFi OI; Boston Scientific) has been recently introduced to clinical practice.…”

The use of a high‐power (50 W), ablation index‐guided protocol for ablation of the cavotricuspid isthmus

“…In this trial, target AI setting was 500 for each lesion at the anterior 2/3 segments of the CTI, while 400 was the target value for the posterior 1/3 segments. CF targets values were 5‐40 g 7 . By using this setup, a very high first‐pass conduction block of 93.0% was achieved, while no major complications occurred.…”

“…8 An additional finding in both previously published studies using CF catheter was that areas with lower CF were located mainly at the tricuspid valve annulus end of the CTI. 7,23 This led to more acute reconductions in this area. To solve this issue, a long steerable sheath (Agilis™ NxT steerable introducer; Abbot) was used in all patients in our study.…”

“…3,5,6 One study using AI guidance for ablation of the CTI showed higher firstpass conduction block of the CTI despite fewer RF applications. 7 In the pursuit of optimized lesions, another current strategy is to increase power. It is known that higher energies are forming larger lesions with smaller lesion depths.…”

“…In clinical practice, AI‐guided pulmonary vein isolation (PVI) and left anterior line ablation show promising results 3,5,6 . One study using AI guidance for ablation of the CTI showed higher first‐pass conduction block of the CTI despite fewer RF applications 7 …”