Background: Several disorders present reflex or persistent increase in vagal tone that may cause refractory symptoms even in a normal heart patient. Cardioneuroablation, the vagal denervation by radiofrequency ablation of the neuromyocardial interface, was developed to treat these conditions without pacemaker implantation. A theoretical limitation could be the reinnervation, that naturally grows in the first year, that could recover the vagal hyperactivity. This study aims to verify the vagal denervation degree in the chronic phase after cardioneuroablation. Additionally, it intends to investigate the arrhythmias behavior after cardioneuroablation.
Methods: Prospective longitudinal study with intrapatient comparison of 83 very symptomatic cases without significant cardiopathy, submitted to cardioneuroablation, 49 (59%) male, 47.3±17 years old, having vagal paroxysmal atrial fibrillation 58 (70%) or neurocardiogenic syncope 25 (30%), New York Heart Association class<II and absence of significant comorbidities. Cardioneuroablation was performed in both atria by interatrial septum puncture, with irrigated conventional catheter and electroanatomic reconstruction. Ablation targeted the neuromiocardial interface by fragmentation mapping (AF-Nests) using the velocity fractionation software, conventional recording, and anatomic localization of the ganglionated plexi. Heart rate variability (time and frequency domain) and arrhythmias were compared by 24h-Holter, before, and 1 year and 2 years after cardioneuroablation. In a 40 month follow-up, 80% of patients were asymptomatic.
Results: Time- and frequency-domain heart rate variability demonstrated significant decrease in all autonomic parameters, showing an important parasympathetic and sympathetic activity reduction at 2-year post-cardioneuroablation (P<0.001). There was no difference in heart rate variability between the 1-year and 2-year post-cardioneuroablation (P>0.05) suggesting that the reinnervation has halted. There was also an important reduction in all bradyarrhythmias and tachyarrhythmias pre-cardioneuroablation versus post-cardioneuroablation (P<0.01).
Conclusions: There is an important and significant vagal and sympathetic denervation after 2 years of cardioneuroablation with a significant reduction in bradyarrhythmia and tachyarrhythmia in the whole group. There were no complications.
Keywords: atrial fibrillation; autonomic nervous system; cardioneuroablation; catheters; heart rate; syncope.