Background: Ablation Index (AI, Biosense Webster, Inc.), utilizing a formula combining force, time and conventional powers, has been validated to correlate with lesion size and ablation outcomes. There is little data on the utility of AI in the setting of high power short duration (HPSD) ablation.
Objective: To compare acute outcomes of pulmonary vein isolation (PVI) in patients with paroxysmal AF undergoing HPSD guided by time versus HPSD guided by AI.
Methods: Using the Carto 3 navigation system, a single transseptal and a Thermocool Smart Touch STSF catheter (Biosense Webster, Inc.), 119 consecutive paroxysmal AF patients underwent wide area circumferential HPSD ablation at 50 watts without carina ablation. 77 patients (154 ipsilateral pulmonary vein pairs) were ablated with time guided RF duration (5-6 seconds on the posterior wall and 10 seconds on the anterior wall). 42 patients (84 ipsilateral pulmonary vein pairs) were ablated with an AI guided RF duration (goal of 350 on the posterior wall with maximum 8 seconds and 450 on the anterior wall with maximum 15 seconds). Overlapping 2mm diameter lesions were required for all ablations. Acute PVI, PVI at 30 minutes, and PVI at 30 minutes with adenosine (24mg) were compared across groups.
Results: Acute PVI rates were similar in the time based and AI based ablation groups (77.3% versus 77.4%, p=1). There was no significant difference in 30 minute PVI rates (93.5% versus 95.2%, p=0.78) or PVI rates at 30 minutes with adenosine (92.4% versus 96.8%, n=0.34). There were no significant differences when comparing either strategy when examining left PVI or right PVI rates acutely, at 30 minutes or with adenosine.
Conclusion: There is no significant improvement in intraprocedural PVI outcomes using AI in combination with HPSD. These results emphasize the need for in vitro validation of lesion indexing with high power short duration and raise the possibility of risk of harm in trying to achieve specific ablation index goals with high power.