Europace Advance Access published online on November 11, 2009
Europace, doi:10.1093/europace/eup352
CLINICAL RESEARCH
Bipolar electrogram amplitudes in the left atrium are related to local conduction velocity in patients with atrial fibrillation
1 EP Expert Doctors—Team Tsuchiya, Koto 3-14-28, Kumamoto, Kumamoto 862-0909, Japan; 2 Division of Cardiology, Saiseikai Futsukaichi Hospital, Fukuoka, Japan; 3 Division of Cardiology, Saga Prefectural Hospital Koseikan, Saga, Japan; 4 Division of Cardiology, Omura Municipal Hospital Cardiovascular Center, Omura, Japan; 5 Department of Internal Medicine 1, Faculty of Medical Oita University, Oita, Japan
Aims: 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.
Methods and 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).
Conclusion: 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.
Key Words: Atrial fibrillation, Low-voltage zone, Conduction velocity, Activation time, Pulmonary vein antrum isolation
* Corresponding author. Tel: +81 96 368 0403, Fax: +81 96 368 0414, Email: tsuchiya{at}s1.kcn-tv.ne.jp
Manuscript submitted 20 August 2009. Accepted after revision 13 October 2009.