title: Characterization of paroxysmal and persistent atrial fibrillation in the human left atrium during initiation and sustained episodes.
abstract: BACKGROUND
  Atrial fibrillation (AF) in the left atrium (LA) is poorly defined in terms of regional differences in the degree of organization, characteristics of paroxysmal and persistent variants, and electrophysiologic events that develop at the onset of episodes.
  
  
  RESULTS
  The study population consisted of 21 patients (15 men and 6 women; mean age 58+/-9.4 years) with paroxysmal (10 patients) or persistent (11 patients) AF. Mapping of the LA during sustained episodes and the onset of AF was performed with a 64-electrode basket catheter. At the onset of AF, repetitive beats starting with atrial premature complexes and ending with generation of the earliest fibrillatory activity were defined as intermediary rhythm. Patients with paroxysmal AF had longer AF cycle lengths and more pronounced regional differences than patients with persistent AF. In total, AF cycle lengths in the LA in patients with persistent AF were 20% shorter than in patients with paroxysmal AF. Initiation of AF was preceded by an intermediary rhythm of 5.5+/-2.5 cycles (6.3+/-2.7 cycles in paroxysmal AF vs 4.2+/-1.0 cycles in persistent AF; P = 0.026). At the onset of AF, the earliest generators of fibrillatory activity were located more frequently in the posterior wall of the LA.
  
  
  CONCLUSIONS
  AF in the LA displays substantial regional differences in terms of AF cycle lengths and degree of organization. Patients with persistent AF have shorter cycle lengths and a higher degree of disorganized activity than patients with paroxysmal AF. Intermediary rhythms play an important role in initiation of AF via activation of generator regions in the LA.
authors.affiliation: Deutches Herzzentrum München and 1 Medizinische Klinik, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Gjin
authors.initials: G
authors.lastname: Ndrepepa
authors.forename: Martin R
authors.initials: MR
authors.lastname: Karch
authors.forename: Michael A E
authors.initials: MA
authors.lastname: Schneider
authors.forename: Sonja
authors.initials: S
authors.lastname: Weyerbrock
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schreieck
authors.forename: Isabel
authors.initials: I
authors.lastname: Deisenhofer
authors.forename: Bernhard
authors.initials: B
authors.lastname: Zrenner
authors.forename: Albert
authors.initials: A
authors.lastname: Schömig
authors.forename: Claus
authors.initials: C
authors.lastname: Schmitt
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000145:classification* / Q000503:physiopathology / Q000628:therapy; D017115:Catheter Ablation; D017147:Defibrillators, Implantable; D015716:Electrocardiography, Ambulatory; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria / Q000503:physiopathology* / Q000601:surgery; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D018879:Ventricular Premature Complexes / Q000145:classification / Q000503:physiopathology