Atrial dilation and altered function are mediated by age and diastolic function but not before the eighth decade.

OBJECTIVES: This study investigated changes in left atrial (LA) volumes and phasic atrial function, by deciles, with normal aging.
BACKGROUND: LA volume increase is a sensitive independent marker for cardiovascular disease and adverse outcomes. To use this variable more effectively as a marker of pathology and a gauge of outcome, physiological changes due to aging alone need to be quantitated.
METHODS: A detailed transthoracic echocardiogram was performed in 220 normal subjects; 89 (41%) were male and their age ranged from 20 to 80 years (mean 45 ± 17 years). Maximum (end-ventricular systole), minimum (end-ventricular diastole), and pre-a-wave volumes were measured using the biplane method of disks. LA filling, passive emptying, conduit and active emptying volumes, and fractions were calculated. Transmitral inflow, pulmonary vein flow, and pulsed-wave Doppler tissue imaging parameters were measured as expressions of left ventricular diastolic function. For purposes of analysis, subjects were divided by age deciles.
RESULTS: LA indexed maximum (0.05 ml/m(2) per year) and minimum (0.06 ml/m(2) per year) volume increased with age but only became significant in the eighth decade (26.0 ± 6.3 ml/m(2), p = 0.02, and 13.5 ± 3.9 ml/m(2), respectively; p < 0.001). Impaired left ventricular diastolic relaxation was apparent in decade 6 and was associated with a shift in phasic LA volumes so that LA expansion index and passive emptying decreased with increasing age, whereas active emptying volume increased.
CONCLUSIONS: In normal healthy subjects, LA indexed volumes remain nearly stable until the eighth decade when they increase significantly. Therefore, an increase in LA size that occurs before the eighth decade is likely to represent a pathological change. Changes in phasic atrial volumes develop earlier consequent to age-related alteration in LV diastolic relaxation.