Reflex syncope is the most common form of syncope. It can lead to injuries and affect quality of life. Nonpharmacological and medical therapies have limited effectiveness. In certain patients, cardiac pacing seem to be beneficial. More recently cardioneuroablation (CNA) has emerged as a novel therapy for reflex syncope. The investigators aim to determine whether CNA is more effective than cardiac pacing at reducing the rate of cardioinhibitory-type reflex syncope.
Aged more than 40 years.
Having a 12-month history that includes at least two documented episodes of spontaneous reflex syncope or one episode that led to injury in addition to at least two presyncopal events, refractory to all recommended types of standard treatment.
Bradycardia-syncope correlation (at least 3 seconds of asystole due to sinus arrest or atrio-ventricular block) confirmed by ECG during spontaneous syncope.
If lacking ECG evidence during spontaneous syncope, a cardioinhibitory response (VASIS type 2A or 2B) on tilt test.
Intrinsic sinus or atrioventricular nodal disease with a proven indication for permanent pacemaker implantation.
Evidence of structural heart disease.
Contraindications to ablation in the right or left atrium.
Life expectancy <12 months.
Parallel
Cardioneuroablation
Procedure/SurgeryGanglionated plexi will be localized using an empirical anatomical approach and/or a fractionated electrogram-based strategy. Point-by-point ablation will be performed using radiofrequency energy and an irrigated tip contact force sensing ablation catheter in a power control mode (35-50 W; AI, 350-500; LSI, 4.5-5.5). The right superior GP (RSGP), left superior GP (LSGP) and posterior left GP (PMLGP) will be targeted during CNA. Radiofrequency applications in other GPs will be left at the discretion of the operator. At the end of the procedure, another EP study and atropine test will be performed. Clinical endpoints for completion of the CNA will be: 1) a HR increase \>20% if the CNA was performed under general anesthesia/deep sedation; 2) improved electrophysiological parameters; 3) significant reduction in atropine response (HR increase \<10% after atropine); and 4) in case of using extracardiac vagal stimulation, lack of response.
Permanent pacemaker therapy
DeviceAll patients in the pacemaker group will receive a dual-chamber pacemaker that has the ability to be programmed in the DDD-CLS algorithm mode (or failing this, a dual-chamber pacemaker with RDR algorithm).
To determine the efficacy of CNA in the treatment of cardioinhibitory reflex syncope in comparison to pacemaker therapy.
Differences in 12-month syncope-free survival between the 2 groups
To evaluate the incidence of complications in the short and long terms for CNA compared to pacemaker therapy
Pacemaker and CNA complication rates at 1 and 12 months
In patients undergoing CNA, evaluation of the degree of long-term reinnervation using the tilt table test (HUTT)
Changes in response to HUTT (type 1-3) at baseline, 1 and 12 months
In patients undergoing CNA, evaluation of the degree of long-term reinnervation using the atropine test
Changes in response (maximum heart rate) to atropine test at baseline, 1 and 12 months
To determine which of the 2 strategies, CNA or cardiac pacing, is superior at preventing a composite of syncope and presyncope
Differences in 12-month syncope- and presyncope-free survival between the 2 groups
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