A randomized comparison of atrial and dual-chamber pacing in 177 consecutive patients with sick sinus syndrome: echocardiographic and clinical outcome

J Am Coll Cardiol. 2003 Aug 20;42(4):614-23. doi: 10.1016/s0735-1097(03)00757-5.


Objectives: 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.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Aged, 80 and over
  • Body Weights and Measures
  • Cardiac Pacing, Artificial / methods*
  • Echocardiography
  • Female
  • Heart Atria / diagnostic imaging
  • Heart Atria / physiopathology*
  • Heart Ventricles / diagnostic imaging
  • Heart Ventricles / physiopathology*
  • Humans
  • Male
  • Middle Aged
  • Sick Sinus Syndrome / diagnostic imaging
  • Sick Sinus Syndrome / therapy*