Left Atrial Volume Index in Healthy Subjects: Clinical and Echocardiographic Correlates

Left atrial (LA) size is related to cardiovascular morbidity and mortality. The relative role of multiple determinants of LA morphology in healthy subjects remains incompletely defined. The aim of this study is to define normal ranges for LA diameters and volume index (LAVi), and to investigate clinical and echocardiographic correlates. A total of 1480 healthy individuals (mean age 36.1 ± 15.5 years, range 20-80; 61% males) underwent a comprehensive transthoracic echocardiography exam including assessment of LAVi calculated using the biplane area-length method at the apical four-chamber and two-chamber views at ventricular end systole (maximum LA size) and indexed for body surface area (BSA). Mean LAVi in the overall population was 29.5 ± 10.8 mL/m(2) (range: 26.1-41.8 mL/m(2) ). Distinct higher values were found in subjects ≥50 years as compared with those <50 years of age (33.4 ± 12.5 vs. 29.1 ± 13.5; P < 0.001). On univariate analysis, LA volume was significantly associated with age (r = 0.48, P < 0.0001), male gender (r = 0.28, P < 0.05), BSA (r = 0.51, P < 0.0001), mitral E/E' (r = 0.47, P < 0.0001), LV end-diastolic volume (r = 0.52, P < 0.0001), and LV mass index (r = 0.31, P < 0.05). Multivariable analysis identified age, BSA, LV end-diastolic volume, and mitral E/E' ratio as the only independent determinants of LA volume (model R(2) = 0.54, P < 0.0001). Gender was an independent predictor of most absolute LA volume, but following normalization to BSA, some associations became nonsignificant. In healthy individuals LAVi vary significantly by age, BSA, diastolic function, and LV dimensions, with lesser effects of gender.