title: Regional left atrial voltage in patients with atrial fibrillation.
abstract: BACKGROUND
  Regional differences in fibrosis, particularly related to the posterior wall and septum, may be important in atrial fibrillation (AF). Using electroanatomic mapping, voltage can be used as a measure of fibrosis.
  
  
  OBJECTIVE
  The purpose of this study was to determine if patients with AF have disproportionately lower voltage in the septal and posterior walls of the left atrium.
  
  
  METHODS
  Sinus rhythm left atrial electroanatomic maps were used in serial patients presenting for left atrial ablation of AF (8-mm tip). Patients undergoing left atrial mapping for focal atrial tachycardia (AT) were used as a comparison group (4-mm tip). Animal experiments were performed to assess the influence of ablation catheter tip size on voltage amplitude.
  
  
  RESULTS
  The posterior and septal walls exhibited the lowest voltages in both groups. Compared with the anterior wall, there was a 3.78-fold greater odds of finding a low-voltage point (<0.5 mV) in the septum (P <.001) and a 3.37-fold greater odds of finding a low-voltage point in the posterior wall (P <.001) in the AF patients; the proportion of low-voltage points by region were not significantly different in the AT group. In the animal model, the mean voltage obtained from an 8-mm ablation catheter was significantly higher (0.30 +/- 0.17 mV) than that obtained from the same points using a 4-mm catheter (0.22 +/- 0.17, P = .05).
  
  
  CONCLUSIONS
  Regional differences in voltage are present in patients with atrial arrhythmias, with AF patients exhibiting significantly more low-voltage areas in the septum and posterior walls.
authors.affiliation: Division of Cardiology, Electrophysiology Section, University of California, San Francisco, San Francisco, California 94143-1354, USA.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Marcus
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Yang
authors.forename: Paul D
authors.initials: PD
authors.lastname: Varosy
authors.forename: Karen
authors.initials: K
authors.lastname: Ordovas
authors.forename: Zian H
authors.initials: ZH
authors.lastname: Tseng
authors.forename: Nitish
authors.initials: N
authors.lastname: Badhwar
authors.forename: Byron K
authors.initials: BK
authors.lastname: Lee
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Lee
authors.forename: Melvin M
authors.initials: MM
authors.lastname: Scheinman
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Olgin
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology*; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed