Acute effects of cardioneuroablation on ventricular arrhythmia inducibility and refractoriness in patients with functional bradyarrhythmias. The Roman 4 study.

Cardioneuroablation (CNA) is a promising method to treat functional bradyarrhythmias. However, whether CNA-induced decrease in the parasympathetic drive to the heart may occur proarrhythmic in the future is not known. To assess acute effects of CNA-induced total vagal denervation on QT interval as well as invasively measured ventricular effective refractory period (VERP), ventricular action potential duration (VAPD) and vulnerability to ventricular arrhythmias. CNA was performed using anatomical approach by means of electro-anatomical mapping and intracardiac echocardiography. Intra-procedural efficacy was assessed using extracardiac vagal stimulation. QTc and QTd intervals were measured from surface ECG. VAPD and VERP were measured from ablation electrode in right ventricle. Measurements were performed at four time-points: at baseline, immediately after CNA, after atropine injection, and finally after isoproterenol bolus. 80 patients (51 females, mean age 42 ± 14 years) underwent CNA. Polymorphic ventricular tachyarrhythmias were induced in 2 females who had pre-existing cardiac conditions. Changes in QTc depended on the method used for correction. Using the Bazett formula, QTc was significantly prolonged, however using the Framingham, Fridericia and Hodges corrections, these changes were much less pronounced or non-significant. QTd remained unchanged across all measurements. The VERP and VAPD values remained unchanged after CNA and after atropine whereas they became significantly shorter following isoproterenol injection. The present study did not demonstrate evidence of acute electrophysiological changes suggesting increased ventricular arrhythmogenicity after CNA in patients without structural heart disease. However, long-term follow-up is needed to confirm lack of proarrhythmic effects of CNA.