Pediatric Norms of Myocardial Function and Dyssynchrony using 2D Speckle-Tracking: Are Z Scores a good idea?

Introduction

Speckle-tracking echocardiography (STE) provides precise assessment of myocardial function (2D strain) and ventricular dyssynchrony. In pediatrics, its clinical application is limited by the absence of reference values. This study aimes to validate and refine Z-score models for 2D strain and dyssynchrony parameters, to assess their reproducibility, and to evaluate their consistency across different ultrasound systems.

Method

Speckle-tracking echocardiography (STE) provides precise assessment of myocardial function (2D strain) and ventricular dyssynchrony. In pediatrics, its clinical application is limited by the absence of reference values. This study aimes to validate and refine Z-score models for 2D strain and dyssynchrony parameters, to assess their reproducibility, and to evaluate their consistency across different ultrasound systems.

Results

The Z-score models by Romanowicz and al. and those developed specially for this study exhibited low explanatory power for 2D strain parameters (R² < 10%). 2D strain parameters demonstrated high inter and intra-observer reproducibility and were independent of the ultrasound system. Dyssynchrony parameters were reproducible but significantly influenced by the imaging system. Variability related to anthropometric parameters lacked clinical significance, and the utility of Z-scores was not established. Unadjusted reference values for all STE parameters are proposed.

Conclusion

Z-score models are not suitable for the analysis of STE parameters in pediatric population. The use of unadjusted reference values is justified due to the absence of clinically relevant anthropometric 2D strain variations during childhood. These findings support the integration of STE into pediatric cardiology, particularly for longitudinal monitoring of cardiac function in congenital heart disease and young cardiomyopathies.