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.