Impact of baseline-pool local impedance on lesion formation using a local impedance-sensing catheter: Lessons from a porcine experimental model

Background: Impact of baseline-pool local impedance (BP-LI) on the lesion size remains unclear. Methods: Lesion size in the porcine left ventricular myocardium was evaluated using the STABLEPOINT™ catheter across various ablation settings and BP-LIs (100, 140, and 180 ohms). Results: A total of 184 lesions were created with different durations (15/30/60 s) at 30 watts or with different powers (30/40/50 W) for 15 s. Lesion depth became deeper (2.8/3.0/3.6 mm at 15 s; p =.007, 4.0/4.9/4.6 mm at 30 s; p =.004, and 5.9/5.5/5.2 mm at 60 s; p =.710) and lesion width wider (5.8/6.3/7.6 mm at 15 s; p =.002, 7.0/8.9/8.9 mm at 30 s; p <.001, and 10.5/9.4/10.5 mm at 60 s; p =.262) as the BP-LI increased under 30 W. Similarly, the lesion depth became significantly deeper (2.1/3.4/3.7 mm at 30 W; p <.001, 3.5/4.6/4.6 mm at 40 W; p <.001, and 4.1/4.7/5.2 mm at 50 W; p =.002) and lesion width broader (5.1/6.9/7.0 mm at 30 W; p <.001, 7.0/7.9/8.1 mm at 40 W; p =.004, and 7.7/8.2/9.6 mm at 50 W; p <.001, respectively) as the BP-LI increased with a 15-s ablation. The relationship between the LI drop and lesion size varied with the different BP-LIs. Adjusted %LI drops (absolute LI drop divided by the BP-LI) minimized the differences between the LI values and lesion formation among the three BP-LIs. Conclusion: Lesion size decreased with lower BP-LI, and the relationship between the LI drops and lesion formation varied across the different BP-LIs. Adjusted %LI drops may serve as a more reliable parameter for predicting the lesion formation.