Validation of Left Atrial Volume Estimation by Left Atrial Diameter from the Parasternal Long-Axis View.

BACKGROUND: Measurement of left atrial (LA) volume (LAV) is recommended for quantification of LA size. Only LA anteroposterior diameter (LAd) is available in a number of large cohorts, trials, or registries. The aim of this study was to evaluate whether LAV may be reasonably estimated from LAd.

METHODS: One hundred forty consecutive patients referred to our outpatient clinics were prospectively enrolled to measure LAd from the long-axis view on two-dimensional echocardiography. LA orthogonal dimensions were also taken from apical four- and two-chamber views. LAV was measured using the Simpson, area-length, and ellipsoid (LAVe ) methods. The first 70 patients were the learning series and the last 70 the testing series (TeS). In the learning series, best-fitting regression analysis of LAV-LAd was run using all LAV methods, and the highest values of F were chosen among the regression equations. In the TeS, the best-fitting regressions were used to estimate LAV from LAd.

RESULTS: In the learning series, the best-fitting regression was linear for the Spearman method (r2  = 0.62, F = 111.85, P = .0001) and area-length method (r2  = 0.62, F = 112.24, P = .0001) and powered for the LAVe method (r2  = 0.81, F = 288.41, P = .0001). In the TeS, the r2 value for LAV prediction was substantially better using the LAVe method (r2  = 0.89) than the Simpson (r2  = 0.72) or area-length (r2  = 0.70) method, as was the intraclass correlation (ρ = 0.96 vs ρ = 0.89 and ρ = 0.89, respectively). In the TeS, the sensitivity and specificity of LA dilatation by the estimated LAVe method were 87% and 90%, respectively.

CONCLUSIONS: LAV can be estimated from LAd using a nonlinear equation with an elliptical model. The proposed method may be used in retrospective analysis of existing data sets in which determination of LAV was not programmed.