Effects of cardioneuroablation on exercise performance in patients with reflex asystolic syncope-preeliminary results

Abstract Background Cardioneuroablation (CNA) is a promising method to treat reflex bradyarrhythmias - cardioinhibitory vasovagal syncope, functional sinus bradycardia or functional atrioventricular block, which are caused by overactivity of the parasympathetic nervous system. The goal of the procedure is to ablate post-ganglionic endings of the parasympathetic part of the autonomic nervous system (ANS), located in ganglionated plexi (GP) in the epicardial fat and in the myocardium. Lack or diminished parasympathetic drive to the heart may be, however, associated with adverse effects. The most frequently encountered complication is heart rhythm (HR) acceleration which may be associated with decreased exercise capacity or effort dyspnea and these symptoms are usually attributed to faster than needed sinus rate at rest and during exercise. Purpose To assess effects of CNA-induced total vagal denervation on cardiorespiratory fitness in patients undergoing CNA due to reflex asystolic syncope. Methods This is a prospective, single-centre observational study (NCT06440291) comprising consecutive patients with reflex bradyarrhythmias who underwent CNA. The procedure was anatomically guided by an electro-anatomical system and intracardiac echocardiography. Vagal denervation was confirmed by extra-cardiac vagal stimulation. A symptom-limited cardiopulmonary exercise test (CPET) was performed before and one year after CNA. The evaluated parameters were resting HR (HRrest), at peak exercise HR (HRpeak), peak oxygen uptake (VO2 peak) (ml/kg/min), and respiratory exchange ratio (RER) at peak exercise. Results Forty-four patients completed one-year follow-up (mean age 40 ± 14 years, 25 (57%) were female). Compared with baseline, one year after CNA there was a significant increase in the VO2 peak (28.1 ± 5.7 vs. 25.7 ± 5.5, p = 0.0016) and HRrest (95 ± 13 vs. 89 ± 15, p = 0.0161) without significant differences in the RER (1.1 ± 0.1 vs 1.1 ± 0.1, p=0.1537) and HRpeak (162 ± 18 vs. 157 ± 21, p = 0.0568) . Conclusions These preliminary findings suggest that, although CNA leads to a significantly increased resting heart rate, the procedure does not affect heart rate at peak exercise. Furthermore, exercise capacity, measured by VO2 peak, is not reduced.