The Significance of the Myocardial Performance Index and Fetal Doppler Abnormalities in Growth-Restricted Fetuses: A Systematic Review of the Literature

Introduction: This review aims to investigate the clinical implications of using the myocardial performance index (MPI), obtained through tissue Doppler imaging (TDI) and spectral Doppler, in assessing fetal cardiac function in growth-restricted fetuses. It explores the MPI's potential in predicting adverse perinatal outcomes and its utility when combined with conventional pulsed-wave Doppler assessments for enhanced fetal well-being evaluations. Material and Methods: A systematic search of PubMed and Google Scholar databases spanning from 2004 to 2023 was conducted to identify pertinent articles on the MPI's clinical application in managing growth-restricted fetuses. Inclusion criteria followed the Fetal Medicine Barcelona definition of fetal growth restriction (FGR) to mitigate study group heterogeneity. The research sources were PubMed and Google Scholar databases, and the review was conducted without any specific clinical or laboratory setting. Only articles meeting the inclusion criteria for FGR, as per the Fetal Medicine Barcelona definition, were considered. Six studies meeting these criteria were included in the review. The review analyzed the correlation between MPI values and conventional Doppler parameters, investigating the progression of myocardial function impairment and its association with the risk of fetal demise. The primary outcome measures included the relationship between MPI values, fetal well-being, and the potential for prenatal cardiac dysfunction in growth-restricted fetuses. Results: The findings indicate that as conventional Doppler parameters deteriorate, MPI values increase, suggesting progressive myocardial dysfunction. The MPI may cross the 95th percentile before abnormal flow in the ductus venosus and aortic isthmus, highlighting the potential for diastolic dysfunction preceding hypoxia in growth-restricted fetuses. Elevated MPI levels were observed in both growth-restricted and small-for-gestational-age (SGA) fetuses, indicating prenatal cardiac impairment. The strong association between an abnormal MPI and perinatal mortality has been shown for early FGR. Conclusions: MPI alterations appear to precede abnormal Doppler parameters in early- and late- onset FGR, potentially indicating diastolic dysfunction preceding hypoxia. Additionally, the MPI correlates with the risk of fetal demise. However, larger studies are needed to establish its sensitivity and specificity. Furthermore, the significance of prenatal cardiac impairment in some SGA fetuses raises questions about its potential impact on perinatal outcomes and cardiovascular programming.