Relation of Fractionated Atrial Potentials with the Vagal Innervation Evaluated by Extracardiac Vagal Stimulation during Cardioneuroablation.

Background - Vagal hyperactivity is directly related to several clinical conditions as reflex/functional bradyarrhythmias and vagal atrial fibrillation (AF). Cardioneuroablation provides therapeutic vagal denervation through endocardial RF ablation for these cases. Main challenges are neuro-myocardium interface identification and the denervation control and validation. The finding that the AF-Nest (AFN) ablation eliminates the atropine response and decreases RR variability suggests that they are related to the vagal innervation. Method - Prospective, controlled, longitudinal, non-randomized study enrolling 62 patients in two groups: AFN group (AFNG-32 patients) with functional or reflex bradyarrhythmias or vagal AF treated with AFN ablation, and a control group (CG-30 patients) with anomalous bundles, ventricular premature beats, atrial flutter, AV-nodal reentry and atrial tachycardia, treated with conventional ablation (non-AFN ablation). In AFNG, ablation delivered at AFN detected by fragmentation/fractionation of the endocardial electrograms and by 3D anatomical location of the ganglionated plexus. Vagal response was evaluated before, during, and post-ablation by 5s non-contact vagal stimulation at the jugular foramen, through the internal jugular veins (ECVS), analyzing 15s mean heart rate, longest RR, pauses, and AV block. All patients had current guidelines arrhythmia ablation indication. Results - Pre-ablation ECVS induced sinus pauses, asystole and transient AV block in both groups showing a strong vagal response (p=0.96). Post-ablation ECVS in the AFNG showed complete abolishment of the cardiac vagal response in all cases (Pre/post-ablation ECVS=p<0.0001), demonstrating robust vagal denervation. However, in the CG, vagal response remained practically unchanged post-ablation (p=0.35) showing that non-AFN ablation promotes no significant denervation. Conclusions - AF-Nest ablation causes significant vagal denervation. Non-AF-Nest ablation causes no significant vagal denervation. These results suggest that AF-Nests are intrinsically related to vagal innervation. ECVS was fundamental to stepwise vagal denervation validation during cardioneuroablation.