title: High-density biatrial pacing protects against atrial fibrillation by synchronizing left atrial tissue.
abstract: OBJECTIVE
  The induction and sustainability of atrial fibrillation (AF) are most commonly due to pulmonary vein (PV) triggers and left atrial (LA) substrate. We hypothesized that simultaneous pacing of the PV ostia, LA, and right atrium (RA) reduces AF susceptibility by synchronizing atrial activity.
  
  
  METHODS
  Mongrel dogs were rapidly paced and maintained in AF for 3 months before cardioversion. Pacing leads were then placed at PV ostia, LA, and RA sites. For single-site pacing (SSP), a drive train (S1) and premature stimulus (S2) were delivered from the same electrode. Multisite pacing (MSP) consisted of S1 at all leads simultaneously and S2 at one site. Pacing trials were performed with decremental S2 coupling intervals (CI) to endpoints of AF induction or refractoriness.
  
  
  RESULTS
  AF induction was reduced by 40.0% with MSP vs. SSP (7.2% vs. 12.0%, p < 0.001). LA S2 sites were more likely to induce AF than RA sites (11.5% vs. 2.6%, p < 0.0001), with benefit of MSP over SSP at LA sites (8.6% vs. 14.6%, p < 0.0001). The CI for AF induction was longer with SSP vs. MSP (119.4 +/- 13.3 vs. 104.4 +/- 11.2 ms, p < 0.05). Atrial activation times were shortened with MSP vs. SSP (87.4 +/- 4.9 vs. 97.1 +/- 10 ms, p < 0.005).
  
  
  CONCLUSIONS
  Atrial synchronization was shown by the decreased activation times with MSP. AF induction was reduced by 40.0% with MSP, supporting the hypothesis of decreased AF susceptibility with synchronization. This is the first study demonstrating AF protection with high-density pacing at LA sites associated with triggers and substrate for the induction and maintenance of AF.
authors.affiliation: University of Illinois at Chicago Section of Cardiology, Chicago, IL 60612, USA.
authors.forename: James C
authors.initials: JC
authors.lastname: Hansen
authors.forename: Rakesh
authors.initials: R
authors.lastname: Latchamsetty
authors.forename: Nimrod
authors.initials: N
authors.lastname: Lavi
authors.forename: Sreekanth
authors.initials: S
authors.lastname: Uppuluri
authors.forename: Daniel
authors.initials: D
authors.lastname: Lafontaine
authors.forename: Roger
authors.initials: R
authors.lastname: Hastings
authors.forename: Boaz
authors.initials: B
authors.lastname: Avitall
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000517:prevention & control*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004285:Dogs; D006325:Heart Atria / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D016896:Treatment Outcome