title: Atrial demand pacemakers in sick sinus syndrome: an efficient and reliable approach in selected patients.
abstract: BACKGROUND
  Atrial demand pacemakers offer the advantages of lower cost and less cumbersome implantation in selected sick sinus syndrome patients with acceptable atrioventricular (AV) conduction. However, concerns about their long-term performance and AV conduction degeneration still worry certain implantation physicians. There were still limited long-term follow-up data of atrial demand pacemakers, especially in oriental people. Thus, we reviewed our long-term follow-up results.
  
  
  METHODS
  From January 1996 to December 1998, all symptomatic sick sinus syndrome patients with atrial demand pacemaker (AAI, AAIR) treatment were retrospectively studied. They were all regularly followed up at our pacemaker clinic. The patients' clinical presentations, coronary angiography, electrophysiology results and their initial implantation parameters were collected. All outpatient follow-up histories, electrocardiogram (EKG) rhythm strips, and chronic threshold test data were also retrieved.
  
  
  RESULTS
  There were 51 patients enrolled in this study, with a mean age of 68 +/- 7 years. The average follow-up duration was 44 +/- 17 months. The baseline His bundle-ventricular (HV) interval was 40 +/- 6 ms and AV 1:1 conduction cycle lengths were up to 388 +/- 65 ms. Two patients (2/51, 3.9%) had acute lead dislodgement within three days and needed reimplantation. During the long-term follow-up, all patients maintained good pacing function. Five patients (5/51, 9.8%) had occasions of sensing failure, as detected by 12-lead surface EKG or Holter monitor, which all resolved after reprogramming of the sensing threshold. Only 1 patient ( 1/51, 1.9%) developed Wenckebach AV block in the daytime as shown by EKG and was later upgraded to a DDDR pacemaker uneventfully. No patient became victim of chronic atrial fibrillation during the long-term follow-up.
  
  
  CONCLUSIONS
  Our follow-up study again suggests that atrial demand pacemakers have good initial implantation and long-term results. The chance of developing AV conduction degeneration during follow-up is quite low (1.9%, average annual incidence 0.5%). AAI and AAIR pacemakers are a reliable and physiological approach to selected sick sinus syndrome patients and should be the pacemaker of choice in suitable cases.
authors.affiliation: Division of Cardiology, Department of Medicine, Taichung Veterans General Hospital, Taichung, Taiwan, ROC.
authors.forename: Kae-Woei
authors.initials: KW
authors.lastname: Liang
authors.forename: Wen-Lieng
authors.initials: WL
authors.lastname: Lee
authors.forename: Chung-Whei
authors.initials: CW
authors.lastname: Hsueh
authors.forename: Ying-Tsung
authors.initials: YT
authors.lastname: Chen
authors.forename: Chih-Tai
authors.initials: CT
authors.lastname: Ting
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D019919:Prosthesis Implantation; D012189:Retrospective Studies; D012804:Sick Sinus Syndrome / Q000628:therapy*