Assessment of echocardiographic left atrial size: accuracy of M-mode and two-dimensional methods and prediction of diastolic dysfunction.

BACKGROUND: Despite the American Society of Echocardiography recommendation to use left atrial volume indexed for body surface area (LAVI) for quantification of left atrial size, a variety of methods are used in clinical practice. Our objectives were to evaluate the accuracy of M-mode and two-dimensional (2D) echocardiographic LA size estimates to LAVI and to determine their ability to predict left ventricular diastolic dysfunction.

METHODS: In 150 consecutive patients, LA diameter (LAD), LA diameter indexed for body surface area (LADI), LA area in the apical two- and four-chamber views (LAA 2c and LAA 4c), biplane area-length LA volume (LAV), and LAVI were obtained. The accuracy of these methods to quantify LA enlargement by LAVI, correlation with clinical parameters, and ability to act as a surrogate for diastolic dysfunction were determined using Pearson correlation coefficients along with univariate and multiple logistic analysis.

RESULTS: The true degree of LA size (with LAVI as standard) was identified by LAD in 45%, LADI in 42%, LAA 4c in 43%, and LAA 2c in 41%. All methods showed positive correlation with age, E/E', mitral regurgitation, and right atrial size and negative correlation with ejection fraction. LAVI was the strongest method to predict any (c = 0.655, P = 0.012) or moderate-severe (P = 0.856 and P < 0.001) diastolic dysfunction. All methods have greater capacity to identify moderate or severe diastolic dysfunction than any degree of diastolic dysfunction alone.

CONCLUSIONS: One-dimensional and 2D methods inaccurately quantify LA size and are inferior to LAVI to predict diastolic dysfunction.