Clinical implications of impedance-guided procedure
As our strategy was not dependent on the AI value, exact AImin value for
durable lesion creation was not determined. Although several data
highlighted the significance of impedance drop in durable lesion
creation,[18, 20] certain limitations need to be
considered such as insufficiency without stable catheter
contact[21] and influence by contact
angle.[22] To avoid esophageal injury, we could
not apply HP application for up to 5 seconds; as such, impedance drop
was not a preferable parameter to predict acute PVRs in the SAE.
Nevertheless, a strong association was identified between ILDmax and
acute PVR in the SAE, and ILDmax of 4.8 mm had a strong association with
durability with a specificity of 90%, suggesting that current protocol
could be improved with tightened lesion creation. As Imp-min of 6.5 ohm
was strongly associated with an acute durability with a specificity of
90% in the segments other than SAE, impedance-guided HPSD-PVI with a
target value of above 6.5 ohm would be suitable in the future.
Occasionally, unipolar signal could not be visible due to electrical
artifacts even with an indifferent electrode; and unipolar signal could
not be reflected by VisiTag on its nature. As impedance drop could be
monitored on-site, and dynamic change visualized by VisiTag color, it
could be used during PVI in persistent AF patients. While efficacy of
impedance-guided HPSD-PVI requires further evaluation, providing
sufficient catheter contacts and avoiding perpendicular contact, this
technique might prove applicable.