title: A clinical comparison between a new dual-chamber pacing mode-AAIsafeR and DDD mode.
abstract: OBJECTIVE
  The aim of this study was to compare the cross-follow-up results in DDD or AAISafeR mode and to describe the safety and effectiveness of this pacing mode.
  
  
  METHODS
  The Symphony 2450/2550 cardiac pacemakers were implanted in 30 patients with sick sinus syndrome between February 2006 and September 2006. They were randomized to the DDD mode or AAISafeR mode for 3 months and then crossed over to the alternate pacing modality for an additional 3 months.
  
  
  RESULTS
  No AAISafeR-related adverse event was observed. All documented episodes of paroxysmal atrial ventricular block caused the immediate switch of the pacing mode from AAI to DDD. The cumulative percent ventricular pacing was significantly reduced in the AAISafeR mode compared with the DDD mode (0.9% [0%-3%] versus 51.3% [2%-91%] P = 0.001; 2.94% [0%-18%] versus 41.18% [0%-65%] P = 0.0001). After 3 months in DDD mode, left atrial diameter, left ventricular enddiastolic diameter, and left ventricular end-systolic diameter increased significantly and left ventricular ejection fraction decreased. However, no obvious changes appeared in 3 months of AAISafeR mode. Switches to DDD occurred during follow-up in 21 patients due to different-degree atrial ventricular block.
  
  
  CONCLUSIONS
  The AAISafeR mode substantially reduces the amount of unnecessary right ventricular pacing in the bradycardia population and effectively prevents the deleterious effects on cardiac performance. An international randomized study will further ascertain the efficacy of this new pacing mode specifically in the prevention of heart failure hospitalization and atrial fibrillation.
authors.affiliation: Department of Cardiology, Institute of Heart Lung and Blood Vessel Disease, Anzhen Hospital Affiliated to Capital Medical University, Beijing, People's Republic of China. Renxj@163.com
authors.forename: Ren
authors.initials: R
authors.lastname: Xue-Jun
authors.forename: Han
authors.initials: H
authors.lastname: Zhihong
authors.forename: Wang
authors.initials: W
authors.lastname: Ye
authors.forename: Du
authors.initials: D
authors.lastname: Huifeng
authors.forename: Zhang
authors.initials: Z
authors.lastname: Jinrong
authors.forename: Chen
authors.initials: C
authors.lastname: Fang
authors.forename: Guo
authors.initials: G
authors.lastname: Jihong
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D012804:Sick Sinus Syndrome / Q000628:therapy*