Key result
Local impedance-guided high-power (50 W) ablation more readily achieved 15-40 Ω drops compared to standard-power (90.1% vs 71.7%) and significantly reduced RF duration (p < 0.05).
Why the study?
Previous studies linked 15-30 Ω local impedance drops to successful radiofrequency lesions and >40 Ω drops to steam pops, prompting evaluation of local impedance-guided ablation using standard versus high power in a preclinical model.
Does high-power local impedance-guided radiofrequency ablation improve efficacy and reduce ablation time compared to standard power in a preclinical model?
Does high-power local impedance-guided radiofrequency ablation improve efficacy and reduce ablation time compared to standard power in a preclinical model?
Absolute Event Rate: 90.1% vs 71.7%
In a preclinical model, high-power local impedance-guided ablation safely reduced RF duration and more consistently achieved target impedance drops compared to standard power.
Supports high-power LI-guided ablation feasibility in reducing RF time; leaves open clinical translation pending human trials.
BACKGROUND: Local impedance (LI) drop measured with microfidelity electrodes embedded in the tip of an ablation catheter accurately reflects tissue heating during radiofrequency (RF) ablation. Previous studies found 15-30 Ω LI drops created successful lesions, while more than 40 Ω drops were associated with steam pops. The objective of this study was to evaluate the safety and efficacy of LI-guided ablation using standard (30 W) and high-power (50 W) in a preclinical model. METHODS: RF lesions were created in explanted swine hearts (n = 6) to assess the feasibility of LI-guided ablation by targeting 10, 20, or 30 Ω (n = 20/group) drops. Subsequently, LI-guided ablation was evaluated in a chronic animal model (n = 8 Canines, 25-29 kg, 30/50 W). During the index procedure point-by-point intercaval line ablation and left inferior pulmonary vein (PV) isolation were performed. RF duration was at the operators' discretion but discontinued early if a 15-30 Ω drop was achieved. Operators attempted to avoid LI drops of more than 40 Ω. At 1-month, durable conduction block was evaluated with electroanatomic mapping followed by necropsy and histopathology. RESULTS: In explanted tissue, terminating ablation at 10, 20, or 30 Ω LI drops created statistically larger lesions (p < .05; 1.8 [1.6-2.4] mm, 3.3 [3.0-3.7] mm; 4.9 [4.3-5.5] mm). LI-guided high-power ablation in vivo significantly reduced RF duration per application compared to standard-power (p < .05; intercaval: 8.9 ± 5.2 vs. 18.1 ± 11.0 s, PV: 9.6 ± 5.4 vs. 23.2 ± 10.3 s). LI drops of 15-40 Ω were more readily achievable for high-power (90.1%, 318/353) than standard-power (71.7%, 243/339). All intercaval lines and PV isolations were durable (16/16) at 1-month. Necropsy revealed no major collateral injury to the pericardium, phrenic nerve, esophagus, or lungs. There was no pericardial effusion, stroke, tamponade, or PV stenosis. Vagal nerve injury was found in two 30 W animals after using 19.7 ± 13.9 and 19.5 ± 11.8 s RF applications. CONCLUSION: LI-guided ablation was found to be safe and efficacious in a chronic animal model. High-power ablation more readily achieved more than 15 Ω drops, reduced RF duration compared with standard-power, and had no major RF collateral injury.
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Osei et al. (2021) studied Preclinical model for radiofrequency ablation (n=14). Local impedance-guided high-power radiofrequency ablation vs. Standard-power radiofrequency ablation (30 W) was evaluated on Achievement of 15-40 Ω local impedance drops. Local impedance-guided high-power (50 W) ablation more readily achieved 15-40 Ω drops compared to standard-power (90.1% vs 71.7%) and significantly reduced RF duration (p < 0.05).
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