Reproducibility analysis of two speckle tracking software for the antenatal semi-automated assessment of the fetal cardiac function.

Introduction Speckle tracking echocardiography (STE) is a non-Doppler modality allowing the semiautomated evaluation of the fetal cardiac function by tracking the speckles of the endocardial borders. Little evidence is available on the evaluation and comparison of different software for the functional assessment of the fetal heart by means of STE. The aim of this study is to evaluate the reproducibility and agreement of two different proprietary speckle tracking software for the prenatal semi-automated assessment of the fetal cardiac function. Methods Prospective study including non-anomalous fetuses referred for different indications at two tertiary academic units in Italy (University of Parma) and Spain (University of Barcelona). 2D clips of the four-chamber view of the fetal heart were acquired by two operators using high-end ultrasound machines with a frame rate higher than 60 Hz. The stored clips were pseudo-anonymized and shared between the collaborating Units. Functional echocardiographic analyses were independently performed using the two proprietary software (TomTec GmbH and FetalHQ®) by the same operators. Inter-software reproducibility of the endocardial global longitudinal strain (EndoGLS) and fractional area change (FAC) of the left (LV) and the right ventricles (RV) and ejection fraction (EF) of the LV were evaluated by the intraclass correlation coefficient (ICC). Results 48 fetuses were included at a median of 31+2 (21+6 - 40+3) gestational weeks. Moderate reproducibility was found for the functional parameters of the LV: EndoGLS (Pearson's correlation 0.456, p<0.01; ICC 0.446, 95%CI (0.189-0.647), p<0.01); EF (Pearson's correlation 0.435, p<0.01; ICC 0.419, 95%CI (0.156-0.627), p<0.01); FAC (Person's correlation 0.484, p<0.01; ICC 0.475, 95%CI (0.223-0.667), p<0.01). On the contrary, RV functional parameters showed poor reproducibility between the two software: EndoGLS (Pearson's correlation 0.383, p=0.01; ICC 0.377, 95%CI (0.107-0.596), p<0.01) and FAC (ICC 0.284, 95%CI (0.003-0.524), p=0.02). Conclusion Our results demonstrate a moderate reproducibility of the speckle tracking analysis of the LV using TomTec GmbH and FetalHQ®, with poor reproducibility for RV analysis.