Reproducibility Challenges in Fetal Cardiac Function Analysis with 2D Speckle-Tracking Echocardiography: Insights from FetalHQ

<b>Background/Objectives</b>: Functional assessment of the fetal heart remains a significant challenge in contemporary perinatology due to the absence of a universally accepted gold standard for such evaluations. The aim of this study was to evaluate the reproducibility of parameters derived from two-dimensional speckle-tracking echocardiography (2D STE) using the FetalHQ software. <b>Methods</b>: We enrolled 87 pregnant women between 19 and 23 weeks of gestation who were undergoing mid-trimester screening at the Provincial Hospital Complex in Kielce. Two independent operators acquired 5 s cine-loops of four-chamber views (4CVs) according to a standardized protocol. Reproducibility was assessed by examining intra- and interobserver variability using the intraclass correlation coefficient (ICC) for several cardiac parameters, including the global sphericity index (GSI), global longitudinal strain (GLS), stroke volume (SV), and fractional area change (FAC). <b>Results</b>: Reproducibility varied substantially across the assessed parameters. The highest intraobserver reproducibility was observed for the 4CV GSI (ICC > 0.9). Moderate intraobserver reproducibility (ICCs ranging from 0.5 to 0.75) was noted for left ventricular (LV) parameters, such as end-diastolic area, end-systolic area, end-diastolic volume, and end-systolic volume. Interobserver variability demonstrated higher ICC values, with excellent reproducibility (ICC > 0.9) for the 4CV GSI and LV volume measurements. Good reproducibility (ICCs between 0.75 and 0.9) was observed for specific left ventricular segmental strain indices, whereas other parameters showed moderate to poor reproducibility (ICC < 0.5). <b>Conclusions</b>: Two-dimensional speckle-tracking echocardiography (2D STE) using FetalHQ exhibits variable reproducibility, which is influenced by the choice of parameters, operator experience, and technical factors. This method holds potential for fetal cardiac assessment; however, additional research is required to improve its predictive accuracy and streamline the evaluation process for routine clinical application.