Background: Current echocardiographic normal reference values and nomograms in healthy adults are commonly normalized by body surface area (BSA) with simple linear or isometric corrections. However, various lines of evidence suggest this method might be flawed. In this study, we established the normative data of left ventricular internal diameter (LViD) by BSA-correlated regression equations with the calculation of Z-scores in healthy Han Chinese adults.
Methods: A total of 577 healthy Han Chinese adults were enrolled (age 44.4±13.0 years, 43% male and 57% female). LViD was acquired from two-dimensional-guided M-mode echocardiography on all participants from the parasternal long-axis view. Linear and nonlinear regression models were built to correlate LViD with BSA in different sexes and age groups. The best-fit models and nomograms are presented with the Z-scores calculated by the models. Residual analysis and reproducibility were evaluated in each best-fit model for reliability.
Results: Body surface area showed polynomial (quadric) correlations with left ventricular end-diastolic diameter (LVDd, R2=0.615, P<0.001) and left ventricular end-systolic diameter (LVDs, R2=0.540, P<0.001). Corresponding regression equations and nomograms for computing the Z-scores of the overall LViD and BSA/sex-specific and BSA/age-specific reference values are presented. Reproducibility, residual distribution, autocorrelation and heteroscedasticity were confirmed in each model.
Conclusions: This study proposes a comprehensive approach for normal reference values of left ventricular internal diameters with echocardiographic nomograms in healthy Han Chinese adults, which may offer a more precise way to diagnose cardiovascular disease in clinical practice.
Keywords: Echocardiography; Z-score; left ventricular internal diameters (LViD); regression models.
2020 Annals of Translational Medicine. All rights reserved.