title: Frequency domain and time complex analyses manifest low correlation and temporal variability when calculating activation rates in atrial fibrillation patients.
abstract: BACKGROUND
  Atrial fibrillation (AF) activation rates have been calculated using both frequency domain and time complex analyses. Direct comparisons of these methods are limited. We report: (1) their correlation when measuring AF activation rates, (2) comparisons of recording durations required to minimize variability, and (3) differences in the temporal reproducibility.
  
  
  METHODS
  AF activation rates were calculated using domain frequency (DF) (via fast Fourier transform) and time complex (TC) (via beat-to-beat activation measurements) analyses. We compared: (1) AF frequencies derived from each method; (2) successively longer subinterval durations to their 16-second reference intervals, and (3) the correlation between consecutively collected 8-second segments and segments collected 10 minutes apart.
  
  
  RESULTS
  There was low intraclass correlation coefficient (ICC = 0.234) when comparing AF activation rates derived using DF versus TC analysis. There was no difference in the frequencies between any of the subintervals compared to their 16-second reference intervals, but variability of measurements was higher for intervals <8 seconds (P < 0.01). Correlations between successive segments and segments taken 10 minutes apart were 0.92 and 0.75 using DF analysis (P < 0.001), and 0.72 and 0.49 using TC analysis (P < 0.001).
  
  
  CONCLUSIONS
  There is low correlation between the DF and TC methods of analyzing AF activation rates. While AF rates do not differ between subintervals and 16-second reference electrograms, the variability of measurements is dependent upon the subinterval duration, and increases for durations less than 8 seconds. AF rates were prone to change over a 10-minute time period. These results point out existing clinical limitations of measuring atrial activation rates in AF patients.
authors.affiliation: Cardiology Division, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, USA. ab542@columbia.edu
authors.forename: Angelo B
authors.initials: AB
authors.lastname: Biviano
authors.forename: James
authors.initials: J
authors.lastname: Coromilas
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Ciaccio
authors.forename: William
authors.initials: W
authors.lastname: Whang
authors.forename: Kathleen
authors.initials: K
authors.lastname: Hickey
authors.forename: Hasan
authors.initials: H
authors.lastname: Garan
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D000925:Anticoagulants / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005583:Fourier Analysis; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D000925:Anticoagulants