Evaluation of cardiac findings using speckle-tracking echocardiography in fetuses with hemoglobin Bart's disease

Hemoglobin (Hb) Bart's disease is a severe manifestation of alpha-thalassemia, resulting in fetal tissue hypoxia and severe anemia. There is limited research available on assessing speckle-tracking analysis of the fetal heart as a response to fetal anemia caused by Hb Bart's disease. This study aimed to assess the diagnostic performance of fetal cardiac measurements derived from speckle-tracking analysis to identify fetuses with Bart's anemia between 17 and 24 weeks of gestation.

This prospective cohort study included 115 women with singleton pregnancies at risk for fetal Hb Bart's disease who underwent either amniocentesis or cordocentesis at Siriraj Hospital, Bangkok, Thailand, in the period between January 2019 and January 2021. Speckle-tracking analysis of the fetal heart was performed in the four-chamber view (4CV), assessing ventricular size and shape, ventricular contractility and left ventricular function, prior to invasive prenatal testing. Logistic regression analysis was used to determine significant cardiac predictors and calculate the probability of a fetus having Hb Bart's anemia.

Among the cohort, 38 (33.0%) fetuses were diagnosed with Hb Bart's disease, and of these, nine (23.7%) cases exhibited fetal hydrops. In comparison to the control group, affected fetuses displayed enlargement of the 4CV, with a globular shape of the right ventricular chamber. Additionally, there were significant reductions in both global and longitudinal left ventricular contractility in non-hydropic affected fetuses compared with the controls. At mid-gestation, no significant differences were observed in transverse contractility or left ventricular function, except for the ejection fraction, between the two groups. Based on logistic regression analysis, combined cardiac measurements derived from speckle-tracking analysis, as a function of head circumference, could differentiate non-hydropic fetuses with Hb Bart's anemia from unaffected fetuses, achieving a sensitivity of 100%, specificity of 98.7% and overall accuracy of 99.1%.

Speckle-tracking analysis of the fetal heart has the potential to accurately identify early fetal cardiac changes during the second trimester in individuals with Bart's anemia. These findings not only offer a novel predictive marker for Hb Bart's anemia, but also help address the question of the underlying mechanisms of heart failure associated with fetal anemia. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.