title: Bipolar electrogram amplitudes in the left atrium are related to local conduction velocity in patients with atrial fibrillation.
abstract: OBJECTIVE
  It is unclear how the amplitude of bipolar electrogram relates to the local conduction velocity (CV) in patients with atrial fibrillation (AF). For 50 AF patients (paroxysmal/persistent AF: 40/10 patients), contact bipolar voltage maps of the left atrium (LA) were constructed during sinus rhythm using EnSite version 6.0J in a point-by-point recording fashion. Patients were divided into Groups A (n = 16), B (n = 19), and C (n = 15) according to the level of the lowest electrogram amplitudes: <0.5, 0.5-0.75, and 0.75-1.0 mV, respectively. Low-voltage zone (LVZ) was defined separately for these groups as a bipolar electrogram amplitude of <0.5, 0.5-0.75, and 0.75-1.0 mV, respectively. The local CV through the LVZ and non-LVZ was calculated along the direction of local activation within each zone for all groups.
  
  
  RESULTS
  Low-voltage zone was consistently found at the septal, anterior, and posterior LA in all groups. In Group A, CV through the LVZ was significantly slower compared with the non-LVZ (0.8 +/- 0.5 vs. 1.4 +/- 0.6 m/s, P = 0.004), but those through the LVZ and non-LVZ were similar in Group B (1.2 +/- 0.5 vs. 1.3 +/- 0.5 m/s, P = 0.07) and Group C (1.5 +/- 0.5 vs. 1.4 +/- 0.6 m/s, P = 0.79). The percentage of points showing fractionated or double potentials in the LVZ was significantly more in Group A (76/293 points, 26%) than in Group B (11/185 points, 6%), and Group C (7/135 points, 5%) (P < 0.0001 and P < 0.0001, respectively).
  
  
  CONCLUSIONS
  There was a significant slowing of local conduction in the LVZ defined as <0.5 mV and was frequently associated with fractionated or double potentials in patients with AF.
authors.affiliation: EP Expert Doctors-Team Tsuchiya, Koto 3-14-28, Kumamoto, Kumamoto, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Sumito
authors.initials: S
authors.lastname: Narita
authors.forename: Takanori
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Yasutsugu
authors.initials: Y
authors.lastname: Nagamoto
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Ando
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Hayashida
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Tanioka
authors.forename: Naohiko
authors.initials: N
authors.lastname: Takahashi
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology*; D018780:Body Surface Potential Mapping / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D009431:Neural Conduction