Cardiac autonomic regulations after right-atrial versus bi-atrial ablation of superior paraseptal ganglion plexus: randomized study guided by ablation index

Abstract Background Cardioneuroablation (CNA) is an effective interventional treatment modality for patients with functional bradyarrhythmias. The procedure includes ablation of the superior paraseptal ganglion plexus (SPSGP), which can be performed in right-atrial (RA) or bi-atrial (BA) fashion. Purpose In this study, we investigated the effects of comparably-sized RA and BA radiofrequency (RF) lesions at the SPSGP region on vagal modulation of sinoatrial (SAN) and atrioventricular node (AVN) assessed by extracardiac vagal stimulation (ECVS). Methods A total of 36 patients (age: 40 ± 10 years, males: 55%) undergoing CNA were randomized 1:1 to two ablation strategies: [1] single RF lesion at the very posterior site of the junction between RA and superior vena cava with ablation index (AI) = 800 (RA group) and [2] the sandwich ablation at the same site (AI = 2 x 400) from endocardial aspects of both atria (BA group). The effect of ablation was investigated by the post-ablation change in sinus rate and the attenuation of the response of the SAN and AVN to ECVS via the right and left internal jugular vein. Sufficient SAN and AVN denervation was arbitrarily defined as maximal ECVS-induced post-ablation pause ≤ 1.5 s. Results The baseline characteristics of patients were comparable between study groups. Following the per-protocol ablation, sinus rhythm accelerated by 10±13 bpm vs. 16±15 bpm (P=0.26) in RA vs. BA groups, respectively. Inducible sinus arrests were shortened by 4.2±3.2 s vs. 5.1±2.9 s (P=0.25), while AV pauses were shortened by 1.1±2.2 s vs. 2.4±3 s (P=0.1) in RA vs. BA groups, respectively. The longest SAN and AVN pauses documented during right or left ECVS and their changes are displayed in the Figure. The postablation response to ECVS was significantly more suppressed in BA compared to RA group for SAN (P=0.05) and AVN (P<0.001). Conclusion Both RA and BA ablation of SPSGP induced significant changes in cardiac autonomic functions. The neuromodulatory effect of BA ablation was noticeably stronger than that of comparably extensive RA ablation.