Key result
Local impedance drop during radiofrequency ablation was significantly larger at successful versus ineffective ablation sites (17.8 vs. 8.7 ohms for defragmentation of atrial potentials; P<0.0001).
Why the study?
It remained to be established whether local tissue impedance can predict effective cavo-tricuspid isthmus ablation and what impedance drop values should be used to judge lesion efficacy.
Does local tissue impedance guidance predict effective lesion formation during CTI ablation in patients with right atrial flutter?
Cohort (n=48)
Does local tissue impedance guidance predict effective lesion formation during CTI ablation in patients with right atrial flutter?
Local impedance drop during radiofrequency ablation is a reliable predictor of effective lesion formation and bidirectional block in right atrial flutter.
LI drop may aid lesion assessment during CTI ablation; leaves open whether LI guidance improves outcomes versus conventional methods.
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.
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Ducceschi et al. (2022) conducted a cohort in Typical right atrial flutter (RAFL) (n=48). Local impedance-guided radiofrequency ablation vs. Ineffective ablation sites was evaluated on Absolute drop in local tissue impedance at successful vs ineffective ablation sites (defragmentation of atrial potentials criteria) (p=<0.0001). Local impedance drop during radiofrequency ablation was significantly larger at successful versus ineffective ablation sites (17.8 vs. 8.7 ohms for defragmentation of atrial potentials; P<0.0001).
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