Fractionated Potential-Guided Cryoablation Targeting Termination of Atrioventricular Nodal Reentrant Tachycardia While Avoiding the Compact Node Electrogram

BackgroundFractionated potential (FP) ablation during atrioventricular nodal reentrant tachycardia (AVNRT), is an effective strategy that minimizes redundant radiofrequency (RF) applications. This study aimed to evaluate the utility of cryoablation targeting FPs to effectively terminate AVNRT while further minimizing redundant cryoapplications. Moreover, we observed what appeared to be compact AVN (cAVN) or proximal His potentials--tiny, dull potentials (TDPs) with continuity to the His potential during sinus rhythm (SR) and AVNRT--in the anteroseptal area. The second aim of this study was to explore the significance of those potentials. MethodsAnalyzed were 53 slow-fast AVNRT patients who underwent ablation procedures. Ultra-high resolution activation maps in the triangle of Koch were obtained during SR (n=34) and AVNRT (n=46). TDPs during SR and AVNRT in the anteroseptal area were identified and annotated using the LUMIPOINT Activation Search tool. ResultsFP areas were observed in 19 patients (56%) during SR and in 46 (100%) during AVNRT. This area corresponded to the AVNRT termination and/or successful ablation site in all, with peak numbers of 8.8{+/-}1.4 during AVNRT and 5.3{+/-}1.3 during SR. The number of ablation points was 3.6{+/-}1.5 for the FP-guided cryoablation (n=32) (Bonferroni corrected P<0.05 vs. anatomical RF; and P<0.05 vs. FP-guided RF), 5.4{+/-}2.1 for the FP-guided RF ablation (n=11) (P=0.0825 vs. anatomical RF), and 8.2{+/-}3.2 for the conventional RF ablation (n=10). Transient AV block occurred in 11 patients (21%). All AV block sites overlapped with the TDP area in the phase just before the His potential during AVNRT and SR, with a confidence setting of [&ge;]24% (35[24-60]%). Conversely, in 42 patients without AV block, no ablation was performed in this area. ConclusionThe FP-guided cryoablation strategy targeting AVNRT termination required fewer cryoapplications than RF ablation. The RF/cryo application in the TDP area during SR and AVNRT posed a risk of AV block.