title: Analysis of the mechanisms initiating random wave propagation at the onset of atrial fibrillation using noncontact mapping: role of complex fractionated electrogram region.
abstract: BACKGROUND
  The complex fractionated atrial electrogram (CFAE) region has been suggested to contribute to the maintenance of atrial fibrillation (AF), but its role for the initiation of AF has not been clarified.
  
  
  OBJECTIVE
  We analyzed the mechanisms of the initiation of random reentrant wave propagation at AF onset, especially in relation to CFAE region.
  
  
  METHODS
  Endocardial mapping of the left atrium using a 3-dimensional noncontact mapping system was performed in 19 patients.
  
  
  RESULTS
  Thirty-two spontaneous AF onset episodes, which were initiated by the focal repetitive discharges (9 ± 9 beats), deriving from the pulmonary veins (PV) (n = 17) and from non-PV CFAE regions (n = 15) were observed. The coupling intervals of the focal discharges that initiated AF (AF-D) were significantly shorter than those that did not initiate AF (non-AF-D) (179 ± 33 ms vs. 217 ± 45 ms, P = .0005). After the AF-D, localized conduction blocks occurred in the CFAE region. Subsequently, the waves propagated to the remainder of the atrium, accompanying the anchored activation around the localized conduction block lines in the CFAE regions. Left atrial activation times of AF-D were significantly longer than those of non-AF-D (151 ± 35 ms vs. 83 ± 17 ms, P < .0001). These longer activation times after AF-D enabled the waves to reenter the previously blocked CFAE region from the opposite direction, and thus the meandering reentrant wave propagation was initiated.
  
  
  CONCLUSIONS
  Unidirectional conduction block in the CFAE region and subsequent prolonged left atrial activation time following short coupled premature discharge were the underlying mechanisms of AF initiation, suggesting the importance of the CFAE region as the substrate for AF onset.
authors.affiliation: Department of Cardiovascular Medicine, Faculty of Life Sciences, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan. yyamabe@kumamoto-u.ac.jp
authors.forename: Hiroshige
authors.initials: H
authors.lastname: Yamabe
authors.forename: Kenji
authors.initials: K
authors.lastname: Morihisa
authors.forename: Junjiroh
authors.initials: J
authors.lastname: Koyama
authors.forename: Koji
authors.initials: K
authors.lastname: Enomoto
authors.forename: Hisanori
authors.initials: H
authors.lastname: Kanazawa
authors.forename: Hisao
authors.initials: H
authors.lastname: Ogawa
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D017115:Catheter Ablation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D004699:Endocardium / Q000503:physiopathology*; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged