ObjectivesThis study aimed to investigate dyssynchronous heart failure in fetuses of mothers with diabetes mellitus (FDM) and fetal controls (FC) using two-dimensional speckle tracking echocardiography (2D-STE) and novel M-mode prototype software (PS). MethodsIn this cohort study 174 fetuses were analyzed, 87 in the FDM-cohort and 87 gestational age-matched fetuses in the FC-cohort. A subgroup of 38 fetuses formed the final case group, with a high median frame rate of approximately 160 frames/s. Using 2D Cardiac Performance Analysis software (TOMTEC, Unterschleissheim, Germany) we measured global longitudinal strain (GLS). TOMTEC PS detected annular displacement by assessing an artificial M-mode on the previously generated tracking. Dyssynchrony (DYS) was calculated as the inter- and intraventricular difference in time to peak GLS or annular displacement. ResultsGreater DYS was observed in all basal myocardial measurement sites and software between FDM-cohort compared to FC-cohort and no significant correlation was found between DYS measurements and gestational age. Intraventricular DYS between the basal segments was statistically significant (all p ≤ 0.036, Wald test of univariate regression models). The PS performed best in DYS measurements identifying right ventricular DYS as potentially predicting FDM (FDM: median, 18.5 (interquartile range [IQR], 13.9–25.0) ms vs. FC: median, 2.7 [IQR, 1.5–3.5] ms; p < 0.001). ConclusionIncreased intraventricular DYS demonstrated an impact of maternal diabetes mellitus on fetal hearts independent of gestational age. The prototype M-mode method identified cardiac dysfunction with higher accuracy than the conventional analysis. High-quality echocardiographic image acquisition is imperative for clinical application of 2D-STE and related advanced technologies.