Title : Fetal modified myocardial performance index (Mod-MPI) assessment in pregnant women with pregestational diabetes mellitus: a longitudinal prospective cohort study
Abstract:
Background: The modified myocardial performance index (Mod-MPI) is a Doppler-based method for assessing fetal cardiac function, adapted from adult cardiology. While promising for monitoring and predicting adverse outcomes in complicated pregnancies, standardized methods, reference ranges, and clinical guidelines are still needed.
Objectives: This study aims to (1) evaluate changes in the modified myocardial performance index (ModMPI) and its components ICT, IRT, and ET during the second and third trimesters in pregnancies complicated by pregestational diabetes mellitus (PGDM) compared to normal pregnancies; (2) assess correlations between Mod-MPI components and glycated hemoglobin (A1C) trends during pregnancy; and (3) estimate the correlation between Mod-MPI variations and maternal body mass index (BMI).
Materials and Methods: This longitudinal prospective cohort study evaluated Mod-MPI in a cohort of patients with pregestational diabetes mellitus (PGDM), including both type 1 and type 2 DM, and a comparative cohort of healthy pregnant women who tested negative for glucose intolerance. Exclusions included twin pregnancies and those conceived via assisted reproductive technologies (ART). From February 2021 to May 2023, participants underwent ultrasounds at three intervals: 19-21 weeks, 26-28 weeks, and 32-34 weeks gestation. Measurements included Mod-MPI, ICT, IRT, ET, maternal weight, A1C levels (PGDM cohort only), fetal biometry, estimated fetal weight, amniotic fluid index, and uterine artery pulsatility index. At later time points, umbilical artery and middle cerebral artery pulsatility indices were assessed to calculate the cerebral placental ratio.
Results: A total of 111 ultrasound examinations were conducted on 37 patients (19 with PGDM and 18 with healthy pregnancies). Baseline characteristics were similar between the cohorts, except for a significantly higher median BMI in the PGDM group (25 kg/m² vs. 21.2 kg/m², p = 0.04). At T2, the median IRT was higher in the PGDM group (37 ms vs. 30.5 ms, p = 0.03), while no significant differences were found for Mod-MPI, ICT, and ET across the time points. Both Mod-MPI and IRT showed a decreasing trend throughout pregnancy in both cohorts (p = 0.04, p = 0.01). Median A1C was consistently higher in type 1 DM compared to type 2 DM at each time point. A1C levels in the PGDM cohort were correlated with both Mod-MPI and IRT at T0 but not at T1 or T2. Median estimated fetal weight (EFW) was significantly higher in the PGDM cohort (2310g vs. 1862.5g, p = 0.02), with no differences observed in AFI, UA-PI, MCA-PI, CPR, or UtA-PI between the groups at any time point.
Conclusions: A higher IRT was detected in the PGDM cohort compared to physiologic pregnancies in the third trimester, suggesting an abnormal diastolic function in fetuses from pregestational diabetic mothers. Regarding the longitudinal evaluation, we described Mod-MPI and IRT trends in decrease, probably related to the increased ventricular function and compliance during pregnancy. This is the first pilot study on an Italian sample that needs to be validated in a larger population.
Audience Take Away:
- Insights into how pregestational diabetes mellitus (PGDM) affects fetal cardiac function, particularly the isovolumetric relaxation time (IRT) during the third trimester.
- Clinicians will have a better tool for monitoring fetal cardiac function, leading to more informed decision making and potentially improved perinatal outcomes.
- The research provides a robust foundation for further investigation into fetal cardiac function in various maternal conditions. It also serves as a practical example of teaching about the effects of maternal health on fetal outcomes and the application of advanced diagnostic tools.
- The correlation between Mod-MPI, maternal A1C levels, and BMI provides new insights that can inform the design of future studies and clinical protocols.
