Sinus nodal denervation by targeting the superior paraseptal ganglionated plexus: randomized comparison of right-atrial and bi-atrial cardioneuroablation guided by ablation index

Abstract

Abstract Background Radiofrequency (RF) catheter ablation of superior paraseptal ganglionic plexus (SPSGP) that significantly suppresses the vagal modulation of the sinus node is used for the treatment of functional bradyarrhythmias. A reasonable effect can be achieved by targeting this plexus from the endocardial aspect of both the right and left atria. Purpose The study aimed to compare the acute efficacy of unifocal right-atrial (RA) and comparably extensive bi-atrial (BA) ablation of SPSGP for sinus nodal denervation as assessed by intraprocedural extracardiac vagus nerve stimulation (ECVS). Methods A population of 22 patients (age: 43±9 years, 55% males) undergoing cardioneuroablation (CAN) for functional bradyarrhythmias were randomized 1:1 to two ablation strategies that included: [1] single RF lesion at the very posterior site of the junction between right atrium and superior vena cava with ablation index (AI) = 800 (RA group) and [2] the same but twice smaller RF lesion (AI = 400) complemented with strictly contralateral left-atrial lesion (AI = 400) at the anterior vestibulum of right superior pulmonary vein (BA group). The effect of ablation was investigated by the post-ablation change in sinus rate and the attenuation of the response of the sinus node to ECVS (frequency: 50 Hz, pulse width: 0.05 ms, output: 1 V/kg [<70V], duration: 5 s) via the right internal jugular vein. Results Per-protocol ablation resulted in sinus acceleration by 9±15 bpm vs. 15±16 bpm (P=0.40) in RA vs. BA groups, respectively. Inducible sinus arrests were shortened by 4.7±4.2 s vs. 6.2±1.5 s (P=0.27) and reached the post-ablation level of 3.0±3.7 s vs. 1.0±0.3 s (P=0.08) in RA vs. BA groups, respectively. The results are also displayed in the Figure as medians, interquartile range (boxes) and total range (whiskers). Complete sinus nodal denervation was achieved in 8/11=73% vs. 11/11=100% patients (Fisher exact test P=0.21) in RA vs. BA groups, respectively. Practically 100% denervation efficacy in the BA group contrasted with 3 patients in the RA group in whom ablation had virtually no effect on ECVS-based indices (duration of post-ablation sinus arrests: 11.2, 8.7, and 5.2 s). Acute effects did not change substantially during the waiting period of 20±5 min. Conclusions In this small study with acute procedural endpoints, unifocal RA ablation of SPSGP appeared numerically less effective for sinus nodal denervation than comparably extensive BA ablation although the difference was formally non-significant. The ECVS-based outcome measure was valuable in detecting the differences between study groups. Change in sinus rate was not a reliable marker of sinus nodal denervation.