Left atrial remodelling in mitral regurgitation--methodologic approach, physiological determinants, and outcome implications: a prospective quantitative Doppler-echocardiographic and electron beam-computed tomographic study.
OBJECTIVE
To define accurate and normal range of echocardiographic left atrial (LA) volume measurement and to assess the prevalence, determinants, and outcome implications of LA enlargement in mitral regurgitation (MR).


RESULTS
We prospectively compared LA volume obtained simultaneously by electron beam-computed tomography (EBCT) and by four echocardiographic methods in 33 test patients. Accurate echocardiographic LA volume measurements were obtained only by biplane area-length method with vertical longitudinal-length (r = 0.95, P < 0.0001; 145 +/- 57 vs. 143 +/- 55 mL, P = 0.57). Using this method, the normal range in 100 normal subjects, the physiological determinants and outcome implications of LA enlargement in 320 patients with organic MR were analysed. In normal subjects, indexed to body surface area, LA index (27 +/- 6 mL/m(2)) was not influenced by age or gender and values > or = 40 mL/m(2) were beyond the upper limit of normal. In MR, the most powerful determinants of LA enlargement were higher regurgitant volume (RVol) and atrial fibrillation (AF) (P < 0.0001), followed by older age, female gender, higher left ventricular end-systolic volume, and mass (all P < 0.001). After diagnosis in sinus rhythm, LA index > or = 40 mL/m(2) predicted superiorly and independently to LA diameter the occurrence of AF [adjusted RR 1.48 (1.06-2.16), P < 0.01] and the combined endpoint of death or need for mitral surgery [adjusted RR 1.61 (1.3-2.0), P < 0.0001].


CONCLUSIONS
LA remodelling can be accurately assessed by echocardiography and LA index > or = 40 mL/m(2) is beyond the normal range. In organic MR, higher LA index is the combined result of multiple physiological effects, provides independent prognostic information, and therefore should be part of a comprehensive echocardiographic examination.
Messika-Zeitoun
David
D
Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, MN 55905, USA.
Bellamy
Michael
M
Avierinos
Jean-Francois
JF
Breen
Jerome
J
Eusemann
Christian
C
Rossi
Andrea
A
Behrenbeck
Thomas
T
Scott
Christopher
C
Tajik
Jamil A
JA
Enriquez-Sarano
Maurice
M
D000368:Aged; D016279:Atrial Function, Left / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D015331:Cohort Studies; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006325:Heart Atria / Q000648:ultrastructure; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D014055:Tomography, Emission-Computed / Q000379:methods; D014463:Ultrasonography