Measurement of Parasternal Long-axis and Commissural Mitral Annulus Diameters Improves the Accuracy of Mitral Annular Cross-sectional Area Calculation

Purpose: Calculation of mitral annular cross-sectional area (CSAMV) using the diameters from the apical long-axis and commissural plane (LAX/CC) method could be more accurate than the calculated area obtained by the annular diameters in the conventional apical four- and two-chamber view (4CV/2CV) method. The purpose of the study is to clarify which approach gives better accuracy: to use the 4CV/2CV method from the apical view or to use the LAX/CC method from the apical view or the parasternal view.Subjects and Methods: Thirty patients without valvular heart diseases were enrolled in this study (22 males, 8 females, 48.7±18.6 years old). CSAMV was measured by three methods as follows: using the conventional 4CV/2CV method from the apical view, and using the LAX/CC method from the apical view and the parasternal view. Left ventricular inflow volume (QLVIT) was calculated using CSAMV obtained by each method. LV outflow volume (QLVOT) was measured by the Doppler method. Correlations and differences between QLVOT and QLVIT were compared among the three methods.Results and Discussion: Compared with the 4CV/2CV method, QLVIT values by the LAX/CC method from the two views were well correlated with QLVOT (4CV/2CV method: r＝0.745, p＜0.01 LAX/CC method from apical view: r＝0.799, p＜0.01 LAX/CC method from parasternal view: r＝0.925, p＜0.01). Further analysis with Bland–Altman plots revealed that the QLVIT obtained by the LAX/CC method from the parasternal view exhibited the closest agreement with QLVOT.Conclusions: CSAMV obtained by the LAX/CC method for both apical and parasternal views is more accurate than that obtained by the conventional 4CV/2CV method. Moreover, the LAX/CC measurement from the parasternal view is better than from the apical view.