Different studies for cardiac ganglionated plexus（GP） ablation to treat vagal vascular syncope, sinus node dysfunction, and functional atrioventricular block have been published. Investigators have developed a more specific approach of cardiac, called cardioneuroablation . This treatment is based on a high-frequency stimulation (HFS) and/or anatomical landmarks to identify GPs in left atrium，which being targeted by radiofrequency catheter ablation. The feasibility of GPs ablation/cardioneuroablation has already been tested in our center in former studies in humans,with a favorable outcome for the patients involved. The results of the former studies have been submitted for publication. However, there are no prospective randomized studies to evaluate the efficacy and safety of atrial ganglionated plexus ablation for SSS before permanent pacemaker implantation.

The purpose of this study of GAPS in humans is to evaluate the efficacy and safety of cardioneuroablation in patients of sick sinus syndrome before they receive a permanent pacemaker.

This is a multicenter,prospective, open, interventional study. All patients will undergo permanent pacemaker implantation. The study will involve eight different steps, from the screening procedure through study completion: screening, enrollment, pharmacological testing, randomization of group allocation, preprocedural assessment, procedure, follow-up, study completion. The dedicated study members (cardiac electrophysiologists, statisticians) and the PI are responsible for recording all data from the trial on the case report forms (CRFs) and completing the study database. The participants will be randomly allocated in a 1:1 ratio to either GPs ablation followed by permanent pacemaker implantation or pacemaker alone. Randomization will be conducted centrally by an independent statistics department(Oxford Medical Center of National Center for Cardiovascular Diseases, Beijing, China) and stratified by center and age(<50 or >=50 years); A dedicated independent physician will be responsible for the safety monitoring. The PI will permit inspection of the trial files and the database by national or international official controlling scientific authorities, if required. The PI will review and monitor completed CRFs and the database at regular intervals throughout the trial.

Inclusion Criteria:

• Sign the informed consent form.
• Diagnosed as SSS, with recurrent symptomatic bradycardia, blackouts, syncope, etc.
• Meet the indications for permanent pacemaker implantation according to the 2018 Chinese pacemaker guidelines (Class I, Class IIa).
• Positive reaction to atropine: The PP interval shortened by more than 20% or the sinus heart rate>60 bpm after intravenous injection of 2 mg of atropine.

Exclusion Criteria:

• Age <14 years old or >75 years old.
• Accompanied with complex congenital heart disease, valvular heart disease, cardiomyopathy and other chronic diseases, such as heart failure (NYHA grade III or IV).
• Acute coronary syndrome or myocardial infarction occurred within 6 months. Cerebrovascular events (such as transient ischemic attack, stroke) or other cerebral blood supply disorders occurred within 3 months.
• History of cardiac surgery and/or permanent cardiac pacemaker implantation.
• TEE or CT found a left atrial thrombus and/or left atrial anteroposterior diameter > 55mm or LVEF < 35%.
• Persistent atrial fibrillation, high-degree or complete atrioventricular block; double or triple fascicular block.