title: A randomized comparison of atrial and dual-chamber pacing in 177 consecutive patients with sick sinus syndrome: echocardiographic and clinical outcome.
abstract: OBJECTIVE
  A randomized trial was done to compare single-chamber atrial (AAI) and dual-chamber (DDD) pacing in patients with sick sinus syndrome (SSS). Primary end points were changes in left atrial (LA) size and left ventricular (LV) size and function as measured by M-mode echocardiography.
  
  
  BACKGROUND
  In patients with SSS and normal atrioventricular conduction, it is still not clear whether the optimal pacing mode is AAI or DDD pacing.
  
  
  METHODS
  A total of 177 consecutive patients (mean age 74 +/- 9 years, 73 men) were randomized to treatment with one of three rate-adaptive (R) pacemakers: AAIR (n = 54), DDDR with a short atrioventricular delay (n = 60) (DDDR-s), or DDDR with a fixed long atrioventricular delay (n = 63) (DDDR-l). Before pacemaker implantation and at each follow-up, M-mode echocardiography was done to measure LA and LV diameters. Left ventricular fractional shortening (LVFS) was calculated. Analysis was on an intention-to-treat basis.
  
  
  RESULTS
  Mean follow-up was 2.9 +/- 1.1 years. In the AAIR group, no significant changes were observed in LA or LV diameters or LVFS from baseline to last follow-up. In both DDDR groups, LA diameter increased significantly (p < 0.05), and in the DDDR-s group, LVFS decreased significantly (p < 0.01). Atrial fibrillation was significantly less common in the AAIR group, 7.4% versus 23.3% in the DDDR-s group versus 17.5% in the DDDR-l group (p = 0.03, log-rank test). Mortality, thromboembolism, and congestive heart failure did not differ between groups.
  
  
  CONCLUSIONS
  During a mean follow-up of 2.9 +/- 1.1 years, DDDR pacing causes increased LA diameter, and DDDR pacing with a short atrioventricular delay also causes decreased LVFS. No changes occur in LA or LV diameters or LVFS during AAIR pacing. Atrial fibrillation is significantly less common during AAIR pacing.
authors.affiliation: Department of Cardiology, Skejby Hospital, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Jens C
authors.initials: JC
authors.lastname: Nielsen
authors.forename: Lene
authors.initials: L
authors.lastname: Kristensen
authors.forename: Henning R
authors.initials: HR
authors.lastname: Andersen
authors.forename: Peter T
authors.initials: PT
authors.lastname: Mortensen
authors.forename: Ole L
authors.initials: OL
authors.lastname: Pedersen
authors.forename: Anders K
authors.initials: AK
authors.lastname: Pedersen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001837:Body Weights and Measures; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004452:Echocardiography; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012804:Sick Sinus Syndrome / Q000000981:diagnostic imaging / Q000628:therapy*