Abstract 2840: Significantly Misclassified Left Atrial Size by Left Atrial Dimension or Area: Comparison with Left Atrial Volume by Two- or Three-Dimensional Echocardiography
Background Determination of left atrial (LA) size is clinically important. LA volume (LAV) calculated from biplane method and corrected for body surface area (BSA) is currently considered as an accurate index of LA size. However, LA anteroposterior dimension (APD) and area (LAA) on two-dimensional echocardiography (2DE) remain the most common measures in routine daily practice. We sought to determine the accuracy and the role of each method in classifying LA enlargement when compared to three-dimensional echocardiography (3DE).
Methods Standard 2DE and 3DE were performed on 65 consecutive patients (mean age 58.4 ± 14.5 years, men 36.9%, BSA 1.89 ± 0.21 cm2) who were in sinus rhythm and had good image quality. APD was measured at end systole on parasternal view and LAA on apical 4-chamber view. LAV was calculated by 3DE and biplane area-length (AL) formula using a shorter perpendicular midline length. Classification of LA enlargement for each parameter was based on the cut-off values recommended by the American Society of Echocardiography.
Results The mean value of LAV-3DE was 74.4 ± 25.4 ml (range 35.2 to 139.4 ml). There were significant correlations (P < 0.001) between LAV-3DE and biplane LAV-AL (r = 0.92, SEE 10.1 ml), LAA (r = 0.88, SEE = 2.3 cm2), and APD (r = 0.76, SEE = 3.8 mm). However, for classifying the degree of LA enlargement, significant underestimation was demonstrated by APD, LAA, and biplane LAV-AL (64.6%, 64.6%, and 10.8%) when using LAV/BSA as the standard. The total misclassification was up to 67.7%, 69.2% and 23.1% for APD, LAA and biplane-LAV, respectively.
Conclusions The commonly used APD and LAA, although correlate well with 3D-LAV, are inappropriate for classifying LA enlargement, given their significant misclassification in LA size. Biplane LAV by area-length method correlates best with LAV-3DE and should be applied in routine clinical practice with a correction for body size.