Clinical implication and future perspectives
The main clinical implication of this study is the recommendation of a
target LI drop of 15 ohm at each RFA with a 4-mm distance between
adjacent ablation points for impedance-guided PV isolation. Factors
associated with an LI drop of <15 ohm in this operator-blinded
study were short RFA time, low pre-RFA LI, and unexpected RFA suspension
due to a rise in esophageal temperature and catheter dislodgement. These
data suggest that insufficient catheter stability, catheter contact with
tissue and RFA time contribute to an insufficient LI drop. Robust
catheter-tissue contact using a contact-force-sensing catheter and
prolongation of RFA time until achievement of an LI drop of ≥15 ohm may
overcome the issue of insufficient ablation lesion formation.
Multifaceted evaluation such as that using pre-existing lesion formation
indexes based on contact force is expected to contribute to the creation
of optimal lesions by radiofrequency ablation. 15, 16
In addition, to extend the potential benefits of impedance monitoring to
improving the safety of the ablation procedure, future studies should
clarify the LI predictor of steam pop. Furthermore, identification of
target LI drop values for optimal lesion formation is needed for a
variety of arrhythmias.