Feasibility and reproducibility of speckle tracking echocardiography in routine assessment of the fetal heart in a low-risk population

OBJECTIVES: The objective of this study was to evaluate the feasibility and reproducibility of speckle tracking echocardiography (STE) in routine fetal cardiac assessments by non-cardiac experts in an NHS clinical setting. METHODS: A prospective longitudinal cohort study was performed from April 2022 to June 2023. During all ultrasound scans between 18 and 40 weeks' gestation a 3 s cineloop of the fetal four chamber view was stored. Parameters of global cardiac function were analysed off-line using STE software by two researchers independently. RESULTS: Of 393 ultrasound scans performed in fetuses fulfilling criteria, 50.9 % were able to be analysed using STE. Intraobserver variability was poor to moderate for both operators (Operator 1 correlation coefficient for FAC 0.28, EF 0.17, SV 0.01, SV/kg 0.00, CO 0.74, CO/kg 0.39; Operator two correlation coefficient for FAC 0.58, EF 0.65, SV 0.67, SV/kg 0.02, CO 0.66, CO/kg 0.31). Interobserver variability was also poor to moderate (Operator 1 vs. Operator two correlation coefficient for FAC 0.01, EF 0.00, SV 0.00, SV/kg 0.00, CO 0.64, CO/kg 0.25; Operator 2 vs. Operator 1 correlation coefficient for FAC 0.16, EF 0.06, SV 0.72, SV/kg 0.008, CO 0.70, CO/kg 0.34). CONCLUSIONS: Routine speckle tracking echocardiography of global cardiac function by non-cardiac experts in low-risk fetuses has low to moderate feasibility and reproducibility in a real-world NHS setting. A high grade of expertise is likely necessary to use STE in order to achieve high reproducibility. Future research should investigate factors contributing to variability in STE measurements and standardisation of protocols.