title: Direction-dependent conduction in lone atrial fibrillation.
abstract: BACKGROUND
  Patients with lone atrial fibrillation (AF) have an abnormal atrial substrate.
  
  
  OBJECTIVE
  The purpose of this study was to determine the role of direction-dependent conduction in patients with lone AF.
  
  
  METHODS
  Twenty-four patients with paroxysmal lone AF and 24 reference patients with left-sided accessory pathways were studied. Multipolar catheters placed at the lateral right atrium, crista terminalis, coronary sinus (CS), and left atrial roof were used to determine direction-dependent conduction characteristics. Biatrial electroanatomic maps were created during sinus rhythm and with distal CS pacing to characterize direction-dependent differences in conduction velocities, electrogram complexity, and voltage.
  
  
  RESULTS
  Differing wavefront directions caused changes in conduction velocity (P <.001), biatrial activation times (P <.001), electrogram fragmentation (P <.001), site-specific conduction delays (P <.001), and voltage (P <.001) in both lone AF and reference patients. These direction-dependent abnormalities were amplified in lone AF patients compared to reference patients, who exhibited greater slowing in conduction velocities (P = .02), prolongation of biatrial activation time (P = .04), increase in number (P <.001) and length (P <.001) of lines of conduction block, increase in proportion of fractionated electrograms (P <.001), and decrease in voltage (P = .03) during distal CS pacing compared to sinus rhythm.
  
  
  CONCLUSIONS
  This study demonstrates the marked direction-dependent conduction abnormalities present in patients with lone AF. These results provide further insights into the critical interplay between the underlying abnormal substrate and differing wavefront directions. The study suggests that direction-dependent conduction abnormalities may explain in part the greater arrhythmogenicity of ectopic triggers from the left atrium rather than the right atrium.
authors.affiliation: Cardiovascular Research Centre, Department of Cardiology, Royal Adelaide Hospital and Discipline of Medicine, University of Adelaide, Adelaide, Australia.
authors.forename: Christopher X
authors.initials: CX
authors.lastname: Wong
authors.forename: Martin K
authors.initials: MK
authors.lastname: Stiles
authors.forename: Bobby
authors.initials: B
authors.lastname: John
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Brooks
authors.forename: Dennis H
authors.initials: DH
authors.lastname: Lau
authors.forename: Hany
authors.initials: H
authors.lastname: Dimitri
authors.forename: Pawel
authors.initials: P
authors.lastname: Kuklik
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Shipp
authors.forename: Thomas
authors.initials: T
authors.lastname: Sullivan
authors.forename: Prashanthan
authors.initials: P
authors.lastname: Sanders
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology*; D018780:Body Surface Potential Mapping; D006328:Cardiac Catheterization / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged