16-18: Collective impacts of power, contact force and ablation time on ablation effect of atrial fibrillation

Introduction: The impact of power, ablation time and contact force (CF) alone on lesion formation in atrial fibrillation ablation has been proven. However, the interaction and collective effect of these factors on ablation effectiveness has not been clearly elucidated.

Methods: 416 ablation points were acquired from 19 patients with paroxysmal atrial fibrillation who underwent pulmonary vein isolation for the first time. The points were collected at the beginning of the procedure at separate sites to avoid the mutual effect. A Thermocool SmartTouch catheter was used for radiofrequency ablation. Energy was applied for 60 s at every site under the same power setting. All data including ablation time, power, CF and impedance were recorded on a Carto 3 system and analyzed off-line. Impedance drop (ID) was used as a surrogate for evaluating ablation effectiveness and ID ≥ 10Ω regarded as an adequate lesion formation. Data were grouped by power (25W, n = 115, 30W, n = 166, and 35W, n = 135) and average CF (<5g, 5-10g, 11-20g and >20g) for analysis.

Results: When CF was <5g, IDs did not raise with power increase and never crossed 10Ω. When CF was ≥5g, IDs were getting higher when power or CF increased. This effect was observed from 0-40s but not after 40s. When CF over 20g and power over 30W, there was a tendency that impedance rose again. (Figure) Conclusions: When CF <5g, ablation effect cannot be improved even with increased power and ablation time. Under CF ≥5g, ablation effect can be reinforced with increased power until 40s. Overheating may occur after 40s under high CF (>20g) and power (35W).

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