This study is prospective Cohort study which was performed in multicenter (General Hospital) in Korea. Inclusion criteria is patients post pacemaker implantation. The purpose is to investigate the occurrence of device detected subclinical atrial fibrillation (atrial high rate episode) in patients post pacemaker implantation and assess long term clinical results.

Inclusion Criteria:

• 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, dilated cardiomyopathy, hypertrophic cardiomyopathy, severe heart valve disease)
• Life expectancy < 12 months
• Patients unable or unwilling to cooperate in the study procedures.

Patients post pacemaker implantation