Assessment of Fetal Modified Myocardial Performance Index in Pregnancies with Gestational Diabetes Mellitus and in Healthy Pregnant Controls

Abstract Gestational diabetes mellitus (GDM) disrupts myocardial function irrespective of evident structural cardiac anomalies. The modified myocardial performance index (Mod-MPI) is a Doppler-based parameter that incorporates both systolic and diastolic performance, acting as a sensitive measure for comprehensive ventricular function. This article assesses and compares fetal Mod-MPI values in pregnancies complicated by GDM and in healthy normoglycemic controls and also evaluates its diagnostic accuracy in detecting subclinical fetal cardiac dysfunction. This prospective case–control study was conducted at a tertiary care center over 18 months. The study included 60 pregnant women (28–32 weeks' gestation) with 30 GDM patients confirmed via the American Diabetes Association oral glucose tolerance testing and 30 matched normoglycemic controls matched for key confounders. Pulsed-wave Doppler echocardiography measured Mod-MPI with sample volume at the mitral–aortic junction with isovolumic contraction time, ejection time, and isovolumic relaxation time calculated via valve click landmarks. Group comparisons, correlation analyses, and receiver operating characteristic (ROC) curve assessments were performed. Mean fetal Mod-MPI was significantly higher in the GDM group compared with controls (0.508 ± 0.040 vs. 0.366 ± 0.045; p < 0.001). The ROC curve revealed excellent diagnostic performance (area under the curve = 0.933) with high sensitivity and specificity achieving an optimal cutoff of 0.46. Fetal Mod-MPI serves as a reliable, feasible, and reproducible index for subclinical fetal myocardial impairment in GDM and facilitates early fetal risk assessment.