Do the left atrial substrate properties correlate with the left atrial mechanical function? A novel insight from the electromechanical study in patients with atrial fibrillation.
BACKGROUND
The atrial substrate is the determinant of occurrence and maintenance of atrial fibrillation (AF), which can induce remodeling of atrial function and structure. This study investigated the relationship between the left atrial (LA) substrate properties and LA mechanical function.


METHODS
Forty-four consecutive patients (50.3 +/- 10.7 years old, 33 men) who presented with sinus rhythm during echocardiographic study before receiving catheter ablation for AF were enrolled. The LA diameter, LA volume, ratio of early and late transmitral filling flow velocities (E/A), LA appendage flow velocity, and transmitral velocity-time integral (VTI) were measured by the echocardiography. The LA empty fraction (LAEF), which was obtained via dividing the difference between maximal and minimal LA volume by maximal LA volume, was calculated as a parameter of the global LA contractile function. The LA global contact voltage mapping (NavX system) was performed before pulmonary vein isolation.


RESULTS
Mean LA voltage and LA low voltage zone index (LVZ index, area with voltage < 0.5 mV, divided by total LA surface area) showed significant correlation with LA diameter and volume, but only the LA LVZ index showed significant correlation with A-wave velocity, transmitral A-wave VTI, and LAEF (r =-0.340, -0.411, -0.426; P = 0.024, 0.006, 0.005, respectively). We divided the LA LVZ index into three groups (< 10%, 10-20%, > 20%). The LAEF got worse and the transmitral A-wave VTI percentage (divided by transmitral VTI) decreased as LA LVZ index increased.


CONCLUSIONS
The LA substrate properties showed close correlation with LA size, but only the LA LVZ index correlated with the LA mechanical function.
Sung
Shih-Hsien
SH
Division of Cardiology and Cardiovascular Research Center, National Yang-Ming University, School of Medicine, Taipei Veterans General Hospital, Taiwan.
Chang
Shih-Lin
SL
Hsu
Tsui-Lieh
TL
Yu
Wen-Chung
WC
Tai
Ching-Tai
CT
Lin
Yenn-Jiang
YJ
Lo
Li-Wei
LW
Wongcharoen
Wanwarang
W
Tuan
Ta-Chuan
TC
Hu
Yu-Feng
YF
Udyavar
Ameya
A
Chen
Shih-Ann
SA
D000328:Adult; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology*; D016279:Atrial Function, Left / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000379:methods; D019560:Echocardiography, Three-Dimensional / Q000379:methods; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged