Bipolar electrogram amplitudes in the left atrium are related to local conduction velocity in patients with atrial fibrillation.
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.
Miyamoto
Koji
K
EP Expert Doctors-Team Tsuchiya, Koto 3-14-28, Kumamoto, Kumamoto, Japan.
Tsuchiya
Takeshi
T
Narita
Sumito
S
Yamaguchi
Takanori
T
Nagamoto
Yasutsugu
Y
Ando
Shin-ichi
S
Hayashida
Kiyoshi
K
Tanioka
Yoshito
Y
Takahashi
Naohiko
N
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