Comparison of the Influence of Right Atrial Septal Pacing and Appendage Pacing on an Atrial Function and Atrial Fibrillation in the Clinical Situation.

Introduction: Recently right atrial septal (RAS) pacing is often selected, but the benefit brought by RAS pacing has not been clear. The aim of this study was to evaluate the differences between RAS pacing and right appendage (RAA) pacing.

Methods: 223 consecutive new patients with a right atrial (RA) electrode during the period from January 2004 to December 2012 were studied retrospectively. They were observed regularly at our pacemaker (PM) clinic, and we measured paced P - sensed QRS interval (pPQi) and left atrial dimension (LAD) during the observation period, furthermore the onset of atrial fibrillation (AF) was assessed.

Results: Mean age was 74.5 years and 104 were men. Mean follow-up period was 4.5 years. 177 patients received RAA pacing and 46 received RAS pacing. There was no difference of LAD and pPQi between patients with RAA pacing and with RAS pacing with more than 50% of percentage as the atrial pacing (%AP). About the comparison between intrinsic PQ interval and pPQi, only RAA pacing made long significantly from intrinsic PQ interval to pPQi (p=0.020, 172.3±46.3 vs. 189.7±38.0). The %AP more than 50% brought less probability of the onset AF. On the other hand, none of pacing sites of RA, pacing mode, and the percentage of ventricular pacing influenced on the probability of the onset of AF. Although in patients with 50% as %AP RAA pacing made patients with AF increased (from 17 to 22), RAS pacing made them decreased (from 14 to 12).

Conclusions: This study did not show the superiority of RAS pacing to RAA pacing, it seems that %AP is more important for the onset of AF. The possibility was seen that RAS pacing reduces the onset of AF.