title: Effect of electrical and structural remodeling on spatiotemporal organization in acute and persistent atrial fibrillation.
abstract: BACKGROUND
  Atrial fibrillation (AF) may originate from discrete sites of periodic activity. We studied the effect of structural and electrical remodeling on spatiotemporal organization in acute and persistent AF.
  
  
  RESULTS
  Atrial effective refractory periods (AERPs) were recorded from five different sites at baseline and after pacing in acute AF (n = 8 dogs) and persistent AF (n = 8). Four persistent AF dogs subsequently were cardioverted to sinus rhythm to allow AERP recovery. Periodicity was quantified by calculating power spectra on left atrial electrograms obtained from a 64-electrode basket catheter. Left atrial size was measured by intracardiac echocardiography and structural changes were assessed by electron microscopy. Mean AERPs decreased after pacing in acute (128 +/- 16 msec to 108 +/- 29 msec, P < 0.001) and persistent AF (135 +/- 16 msec to 104 +/- 24 msec, P < 0.0001). AERP recovery was established after 7 days of sinus rhythm. Structural changes were mild in acute AF, severe in persistent AF, and remained severe after AERP recovery. A single dominant frequency was identified in 94% of acute AF bipoles, 57% in persistent AF, and 76% after AERP recovery. Average correlation coefficient was 0.82 among acute AF bipoles, 0.63 in persistent AF, and 0.73 after AERP recovery.
  
  
  CONCLUSIONS
  Transition from acute to persistent AF is associated with loss of spatiotemporal organization. A single dominant frequency recruits the majority of the left atrium in acute AF. Persistent AF, however, is associated with structural remodeling and dominant frequency dispersion. Recovery of refractoriness only partially restores spatiotemporal organization, indicating a major role for structural remodeling in the maintenance of persistent AF.
authors.affiliation: Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Akar
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Everett
authors.forename: Lai-Chow
authors.initials: LC
authors.lastname: Kok
authors.forename: J Randall
authors.initials: JR
authors.lastname: Moorman
authors.forename: David E
authors.initials: DE
authors.lastname: Haines
mesh_terms: D000208:Acute Disease; D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology*; D016275:Atrial Function / Q000502:physiology*; D004195:Disease Models, Animal; D004285:Dogs; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D019277:Entropy; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000503:physiopathology; D008955:Models, Cardiovascular; D020127:Recovery of Function / Q000502:physiology; D012032:Refractory Period, Electrophysiological / Q000502:physiology; D012720:Severity of Illness Index; D013223:Statistics as Topic; D016896:Treatment Outcome