This study is prospective randomized study which was performed in multicenter (General Hospital) in Korea. Inclusion criteria is patients who developed atrial fibrillation/flutter/tachycardia after pacemaker implantation among AF-pacemaker study (ClinicalTrials.gov Identifier: NCT03303872). The purpose is to investigate the recurrence rate of AF/AFL/AT in both groups after randomization for 60 months (5 years) in patients post pacemaker implantation and assess long term clinical results.

Inclusion Criteria:

• Patients who developed atrial fibrillation/flutter/tachycardia after pacemaker implantation among AF-pacemaker study (ClinicalTrials.gov Identifier: NCT03303872).
• Age: 18-80 years
• Patients eligible for the indications for permanent pacemaker implantation in accordance with 2016 revised Korean indication guideline on cardiac pacemaker implantation
• Estimated percentage of atrial pacing >40% under sinus rhythm (LR≥60bpm, close hysteresis and rest rate)
• Estimated percentage of ventricular pacing >40% under sinus rhythm (LR≥40bpm, DDD pacing, close hysteresis and rest rate)
• Patients who are willing to sign the informed consent.
• Patients who are willing to receive the implantation and post-operative follow-up.

Exclusion Criteria:

• Persistent or permanent AF
• Severe hepatic and renal insufficiency (AST or ALT ≥ three times of normal upper limit; SCr > 3.5 mg/dl or Ccr < 30ml/min)
• Thyroid gland dysfunction
• Pregnancy
• Malignant tumor
• Severe organic heart disease (such as moderate to severe mitral regurgitation, severe valvular regurgitation and stenosis, dilated cardiomyopathy, hypertrophic cardiomyopathy, severe heart valve disease)
• Life expectancy < 12 months
• Patients unable or unwilling to cooperate in the study procedures.