Late atrioventricular block after AVNRT ablation: the role and approach of cardioneuroablation

Abstract Background Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of regular supraventricular tachycardia and is typically treated with catheter ablation of the slow pathway. Although this procedure has high success and low complication rates, intraoperative atrioventricular block (AVB) remains a significant complication. Previous studies also highlight an increased risk of late pacemaker implantation due to AVB following AVNRT ablation (95 ± 55 months post-procedure).(1) Cardioneuroablation (CNA) has recently emerged as a potential alternative to pacemaker implantation in patients with cardioinhibitory reflex syncope and functional cardiac conduction disorders,(2,3) but its role in managing late AVB post-AVNRT ablation remains unexplored. Purpose This study aimed to evaluate the efficacy of CNA in patients with syncope caused by late-onset paroxysmal AVB after AVNRT ablation, assessing whether CNA could restore normal conduction and prevent syncope, thereby avoiding pacemaker implantation. Methods Three patients with recurrent syncope due to paroxysmal AVB were enrolled in this prospective study, with a mean of 111.7 months since AVNRT ablation. All had normal infrahisian conduction and preserved suprahisian functional reserve, confirmed by atropine tests. CNA was performed using a biatrial approach with the Ensite X EP System, guided by anatomical mapping and local atrial electrograms. Radiofrequency (RF) energy was applied to the inferior paraseptal ganglionated plexus (IPSGP, from both the right and left atria) and the left superior ganglionated plexus (LSGP), with varying application order across patients (Figure 1). Acute success was defined as abolition of the atropine response at the atrioventricular node (atrial-His interval and antegrade Wenckebach point [AWP]) , and mid-term success as absence of syncope, a negative cardioinhibitory tilt test response, and normal Holter monitoring at follow-up. Results All patients achieved acute procedural success, with baseline parameter improvements and complete abolition of the atropine response at the atrioventricular node (Table 1). In all patients, the main improvement of the AWP occurred after applications at the IPSGP. Post-CNA, all patients remained free from syncope during follow-up (9, 5, and 2 months, respectively). Post-CNA tilt testing showed vasodepressor responses, with no conduction abnormalities observed on Holter monitoring. Conclusions CNA may offer a promising alternative to pacemaker implantation in patients with syncope due to late-onset paroxysmal AVB following AVNRT ablation. This is the first study exploring CNA in this context, suggesting that parasympathetic modulation via CNA could enhance AV conduction and potentially delay or avoid pacemaker implantation. The IPSGP appears to be the critical target, and focusing RF applications in this area for selected patients may maintain efficacy while enhancing safety by minimising RF application numbers.Figure 1.Anatomical location of the GP Table 1.Summary of patient data and CNA