Customized AI Approach
Various target AI values have been proposed in previous studies, being
rounded up from 400 to 550 for the anterior/roof segments and from 330
to 400 for the posterior/bottom segments. The AI-guided PVI produced the
higher acute procedure success and the lower AF recurrence
rate.4,12-15 However, target AIs in the previous
studies were usually based on a physician’s expertise and experience,
not on a precise ablation target.
WT in the area surrounding the PV is heterogenous and varies among
patients; a single AI cut-off approach might not be suitable to all
patients. Haines et al. designed an open-irrigated RF ablation catheter
with an ultrasound transducer at the tip. They performed near-field
ultrasound imaging with this catheter in animal experiments. This
approach could assess WT and lesion depth of ablation required for
transmural lesion formation to optimize power
delivery.16 AI was correlated with lesion depth,
width, and volume in an experimental study;17 it seems
to yield better therapeutic performance when adjusted to the precise
ablation target. WT-based AI-adjustment in this study would exploit the
unique advantage of AI-guided ablation to its full potential. To date,
the RF delivery method has been extensively discussed for durable PVI,
but the precise ablation target also deserves more attention.
Nevertheless, we had a few cases of first-pass isolation failure, the
acute reconnection, and AF recurrence, suggesting that our protocol
should be further optimized.
It has recently been reported that high power-short duration (HPSD)
ablation decreased the total RF application duration of PVI in
paroxysmal AF patients.18 Experimental studies
demonstrated that HPSD (90 W, 4 sec) creates wider but shallower lesions
than conventional RF ablation,19 implying that the WT
in a target RF region is important for effective HSPD ablation. The HSPD
ablation may be inadequate for a thicker WT area and the precise WT
evaluation may help to determine the most suitable region for the HSPD
ablation.