title: Validation of the frequency spectra obtained from the noncontact unipolar electrograms during atrial fibrillation.
abstract: BACKGROUND
  Noncontact mapping (NCM) can record virtual unipolar electrograms (Egs) from multiple sites simultaneously; therefore, it has the potential to perform simultaneous frequency mapping during atrial fibrillation (AF). The aim of this study was to validate the frequency spectra of the noncontact unipolar Egs in both atria.
  
  
  METHODS
  This study enrolled 12 patients (age = 61 +/- 16 years) with paroxysmal or persistent AF who underwent catheter ablation guided by NCM. Noncontact and contact unipolar Egs were recorded simultaneously. The cross-correlation of the Eg morphology, activation time difference of the time-domain signals, and resultant frequency spectra were compared via dominant frequency (DF) and magnitude-squared coherence (MSC).
  
  
  RESULTS
  A total of 159 sites were analyzed during AF. The variables that independently predicted a higher correlation between the contact and noncontact electrogram morphology were a smaller activation timing difference P < 0.01), smaller distance of the mapping sites to the array center (P = 0.01), and higher atrial voltage (P = 0.03). However, the average MSC of the frequency band within the physiologic range of AF (2 to 15 Hz) was only affected by the activation timing difference (P = 0.002). The DF value between the contact and noncontact unipolar signals correlated well with each other throughout the right atria and left atria in 94% of the mapping sites (r = 0.87, P < 0.001).
  
  
  CONCLUSIONS
  The accuracy of the noncontact unipolar Eg morphology decreased when the mapping sites harbored a smaller atrial voltage and longer distance to the array center. The DF difference between the contact and noncontact unipolar Eg was not affected by the distance to the array center.
authors: Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taiwan.
authors: Yenn-Jiang
authors: YJ
authors: Lin
authors: Satoshi
authors: S
authors: Higa
authors: Tsair
authors: T
authors: Kao
authors: Han-Wen
authors: HW
authors: Tso
authors: Ching-Tai
authors: CT
authors: Tai
authors: Shih-Lin
authors: SL
authors: Chang
authors: Li-Wei
authors: LW
authors: Lo
authors: Wanwarang
authors: W
authors: Wongcharoen
authors: Shih-Ann
authors: SA
authors: Chen
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity