In vivo assessment of catheter-tissue contact using tissue proximity indication and its impact on cardiac lesion formation in pulsed field ablation.

Background: No evidence exists regarding whether tissue proximity indication (TPI), an impedance-based contact indicator, can improve in vivo lesion formation and durability during pulsed field ablation (PFA).

Objective: This in vivo study investigated the relationship between catheter-tissue contact and lesion formation.

Methods: In 5 porcine subjects, PFA applications were delivered at 35 atrial target sites using the VARIPULSE variable-loop circular catheter with the CARTO 3 mapping system. We compared acute ablative low-voltage zones (LVZs; <0.5 mV), chronic LVZs, and pathologic lesions between no/minimum contact (TPI-negative/flickering TPI-positive status) and consistent tissue contact (consistent TPI-positive status) for typical clinical scenarios and tissue tenting (TPI-positive status with electrodes extensively away from the 3-dimensional mapping surface) for safety margin. Ultrasound imaging also confirmed contact category assessments.

Results: Acute and chronic LVZs were significantly larger with consistent contact compared with no/minimum contact, including pathologic lesion length (36.0 ± 12.5 mm vs 17.4 ± 15.2 mm; P = .002) and maximum width (10.3 ± 2.7 mm vs 5.7 ± 5.1 mm; P = .035); results with tenting (length: 34.6 ± 11.7 mm; width: 11.3 ± 1.9 mm) were comparable to consistent contact. Lesion transmurality was achieved in all lesions with consistent contact or tissue tenting but only in 54.5% with no/minimum contact (P = .001 for each). The TPI-based electrode contact distance, measured as the cumulative length of the multielectrode catheter tip positive for TPI, significantly correlated with lesion length, maximum width, and transmurality.

Conclusion: Consistent TPI-based contact during PFA was strongly associated with distinct chronic transmural lesions, emphasizing the importance of tissue contact in optimizing circumferential lesion formation with circular PFA catheters.