Atrioventricular block (AVB) is a rare but serious acute complication of atrioventricular nodal reentrant tachycardia (AVNRT) ablation. Additionally, compared to the general population, patients who undergo AVNRT ablation have an increased risk of requiring pacemaker implantation due to late-onset AVB. Cardioneuroablation (CNA) has emerged as a promising alternative to pacemaker implant in patients with recurrent cardioinhibitory reflex syncope and functional cardiac conduction disorders. However, its role in managing late AVB post-AVNRT ablation has not been established.
This prospective study included three patients who experienced syncope due to paroxysmal AVB 97-127 months after successful AVNRT ablation. All patients exhibited normal infrahisian conduction and preserved functional reserve of suprahisian conduction, as assessed by an atropine test. CNA was performed using a biatrial approach with the Ensite X EP System, guided by both anatomical mapping and local fragmented atrial electrograms. Radiofrequency (RF) energy was delivered to the inferior paraseptal ganglionated plexus (IPSGP) and the left superior ganglionated plexus (LSGP). Acute procedural success was defined as complete abolition of atropine response at the atrioventricular node. Clinical success was defined as no recurrence of syncope, no cardioinhibitory response during tilt testing, and normal conduction on Holter monitoring.
Acute procedural success was achieved in all cases, with significant reductions in the antegrade Wenckebach point (AWP) following RF ablation at the IPSGP and LSGP. Post-CNA atropine tests showed no changes in AH interval or AWP response in any patient. Post-CNA tilt testing revealed vasodepressor responses in all patients, and Holter monitoring showed no conduction abnormalities. During follow-up (6-13 months), all patients remained free of syncope.
CNA appears to be a promising alternative to pacemaker implantation for patients with late-onset paroxysmal AVB following AVNRT ablation. Targeting the IPSGP, in particular, may be crucial for optimizing outcomes. Larger studies are needed to confirm these findings and evaluate the long-term efficacy of CNA in this patient population.

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