title: Stability of rotors and focal sources for human atrial fibrillation: focal impulse and rotor mapping (FIRM) of AF sources and fibrillatory conduction.
abstract: BACKGROUND
  Several groups report electrical rotors or focal sources that sustain atrial fibrillation (AF) after it has been triggered. However, it is difficult to separate stable from unstable activity in prior studies that examined only seconds of AF. We applied phase-based focal impulse and rotor mapping (FIRM) to study the dynamics of rotors/sources in human AF over prolonged periods of time.
  
  
  METHODS
  We prospectively mapped AF in 260 patients (169 persistent, 61 ± 12 years) at 6 centers in the FIRM registry, using baskets with 64 contact electrodes per atrium. AF was phase mapped (RhythmView, Topera, Menlo Park, CA, USA). AF propagation movies were interpreted by each operator to assess the source stability/dynamics over tens of minutes before ablation.
  
  
  RESULTS
  Sources were identified in 258 of 260 of patients (99%), for 2.8 ± 1.4 sources/patient (1.8 ± 1.1 in left, 1.1 ± 0.8 in right atria). While AF sources precessed in stable regions, emanating activity including spiral waves varied from collision/fusion (fibrillatory conduction). Each source lay in stable atrial regions for 4,196 ± 6,360 cycles, with no differences between paroxysmal versus persistent AF (4,290 ± 5,847 vs. 4,150 ± 6,604; P = 0.78), or right versus left atrial sources (P = 0.26).
  
  
  CONCLUSIONS
  Rotors and focal sources for human AF mapped by FIRM over prolonged time periods precess ("wobble") but remain within stable regions for thousands of cycles. Conversely, emanating activity such as spiral waves disorganize and collide with the fibrillatory milieu, explaining difficulties in using activation mapping or signal processing analyses at fixed electrodes to detect AF rotors. These results provide a rationale for targeted ablation at AF sources rather than fibrillatory spiral waves.
authors.affiliation: Arizona Heart Hospital, Phoenix, Arizona.
authors.forename: Vijay
authors.initials: V
authors.lastname: Swarup
authors.forename: Tina
authors.initials: T
authors.lastname: Baykaner
authors.forename: Armand
authors.initials: A
authors.lastname: Rostamian
authors.forename: James P
authors.initials: JP
authors.lastname: Daubert
authors.forename: John
authors.initials: J
authors.lastname: Hummel
authors.forename: David E
authors.initials: DE
authors.lastname: Krummen
authors.forename: Rishi
authors.initials: R
authors.lastname: Trikha
authors.forename: John M
authors.initials: JM
authors.lastname: Miller
authors.forename: Gery F
authors.initials: GF
authors.lastname: Tomassoni
authors.forename: Sanjiv M
authors.initials: SM
authors.lastname: Narayan
mesh_terms: D000465:Algorithms; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology*; D001683:Biological Clocks; D018780:Body Surface Potential Mapping / Q000379:methods*; D002908:Chronic Disease; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D009431:Neural Conduction; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States
keywords: FIRM mapping; atrial fibrillation; catheter ablation; focal impulse; rotors