Atrial Fibrillation With Sinus Node Dysfunction: Intensive Device Follow-up

Inclusion Criteria: * Age from 18 - 80 years * Longest RR interval ≥ 3 seconds in sinus rhythm or when atrial arrhythmia (atrial fibrillation/atrial arrhythmia/atrial flutter) is converted to sinus rhythm (documented by either holter monitor or electrogram). * Meet the indications of permanent pacemaker implantation in patients with SND according to the 2012 ACCF/AHA/HRS Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities. * Evidence of paroxysmal atrial fibrillation ( two or more symptomatic episodes within 6 months) * Willing to sigh informed consent Exclusion Criteria: * Type II second-degree or three-degree atrioventricular block (in sinus rhythm) * Intrinsic PR interval ≥ 300 ms in sinus rhythm * Persistent AF（including long-standing persistent AF） * Severe structural heart disease(e.g. ischemic heart disease that requires revascularization, rheumatic heart disease that requires valve replacement, cardiomyopathy except hypertensive myocardial hypertrophy) * Work high above the ground or heavy physical labour * Malignant ventricular arrhythmias * New York Heart Association (NYHA) class III or IV * AF secondary to electrolyte imbalance, thyroid dysfunction, vasovagal reaction or other reversible or non-cardiac causes * Previous procedures dealing with AF (including radiofrequency ablation and surgical operation) * Cardiac implantable electronic device implantation history * Severe hepatic and renal dysfunction(serum creatinine above the upper normal limit of the center, or chronic renal dysfunction ; ALT or AST more than 2 times the upper normal limit of the center, or bilirubin more than 2 times the upper normal limit of the center, or hepatic cirrhosis) * Contraindication to propafenone/amiodarone/dronedarone(except bradycardia) * Contraindication to oral anticoagulants * Women who are pregnant * Presence of malignant tumor * Severe coagulation disorder (without any anticoagulation treatment) * The investigators do not think the patient is eligible for this study * Patient is unwilling to cooperate with the study procedures