Study population
The institutional review boards at the Kitasato University school of medicine approved retrospective review of these data. The study population consisted of 258 consecutive patients newly implanted with CIEDs between January 2010 and December 2014 at our institute. For the study purpose of monitoring for AHREs, patients without atrial leads were excluded. The CIEDs used in this study consisted of permanent DDD pacemakers for SSS or atrioventricular block. Patients with implantable cardioverter-defibrillators and cardiac resynchronization therapy devices were excluded because such patients are believed to be at higher risk for cardiac events. Each device was implanted in accordance with the class I to IIa indications of the current American Heart Association/JCS guidelines.11,12 Patients with idiopathic cardiomyopathy, end-stage renal disease (with hemodialysis), previously documented AF and/or without 12-lead ECG recordings made just prior to DDD pacemaker implantation were also excluded. The absence of AF history was confirmed by repeated body-surface ECG and/or Holter ECG. Finally, a total of 101 patients were included in the study analysis (Figure 1).