Optimized radiofrequency lesions through local impedance guidance for effective CTI ablation in right atrial flutter

Abstract

Background Although radiofrequency (RF) catheter ablation of cavo‐tricuspid isthmus (CTI) is an established treatment for typical right atrial flutter (RAFL), it remains to be established whether local tissue impedance (LI) is able to predict effective CTI ablation and what LI drop values during ablation should be used to judge a lesion as effective. We aimed to investigate the ability of LI to predict ablation efficacy in patients with RAFL. Methods RF delivery was guided by the DirectSense™ algorithm. Successful single RF application was defined according to a defragmentation of atrial potentials (DAP), reduction of voltage (RedV) by at least 80% or changes on unipolar electrogram (UPC). The ablation endpoint was the creation of bidirectional conduction block (BDB) across the isthmus. Results 392 point‐by‐point RF applications were analyzed in 48 consecutive RAFL patients. The mean baseline LI was 105.4 ± 12Ω prior to ablation and 92.0 ± 11Ω after ablation (p < 0.0001). According to validation criteria, absolute drops in impedance were larger at successful ablation sites than at ineffective ablation sites (DAP: 17.8 ± 6Ω vs. 8.7 ± 4Ω; RedV: 17.2 ± 6Ω vs. 7.8 ± 5Ω; UPC: 19.6 ± 6Ω vs. 10.1 ± 5Ω, all p < 0.0001). LI drop values significantly increased according to the number of criteria satisfied (ranging from 7.5Ω to 19.9). BDB was obtained in all cases. No procedure‐related adverse events were reported. Conclusions A LI‐guided approach to CTI ablation was safe and effective in treating RAFL. The magnitude of LI drop was associated with effective lesion formation and BDB and could be used as a marker of ablation efficacy. Clinical trial registration Catheter Ablation of Arrhythmias with a High‐Density Mapping System in Real‐World Practice (CHARISMA). URL: http://clinicaltrials.gov/ Identifier: NCT03793998.

Local impedance and contact force guidance to predict successful cavotricuspid isthmus ablation with a zero-fluoroscopy approach

“…LI measurement was first tested with a 4.5 mm tip ablation catheter with micro-electrodes (Intellanav MiFi OI TM , Boston Scientific, Marlborough, U.S.A). LI drop measured with this catheter proved to be a good marker of lesion effectiveness in CTI ablation (4,19,29). Currently, a new catheter capable of measuring at the same time LI and CF is available (Intellanav StablePoint TM , Boston Scientific, Marlborough, U.S.A).…”

“…In the past few years, a new ablation catheter (Intellanav MiFi OI™, Boston Scientific, Marlborough, U.S.A) capable of measuring real-time LI and LI drop while applying RF has been developed. LI drop results from tissue heating and constitutes a good predictor of lesion formation, catheter-tissue coupling, and effective ablation in different arrhythmic substrates, such as atrial fibrillation ( 3 ) and CTI-dependent atrial flutters ( 4 , 5 ). More recently, a new catheter with new technology and a different design (ie, without micro-electrodes) has been introduced (Intellanav StablePoint™, Boston Scientific, Marlborough, U.S.A), measuring not just LI drop but also assessing CF.…”