(538) Cardiac structural and functional assessment of monochorionic twin pregnancies complicated by selective fetal growth restriction

Objective: Selective fetal growth restriction (sFGR) complicates 10-15% of monochorionic twin gestations. Prior studies reported neonatal cardiac hypertrophy present in 25% of twins impacted by sFGR, most commonly the larger twin (AGA, 80%). Our primary objective was to characterize fetal cardiac structural and functional echocardiogram findings in these complex twins pairs.

Study Design: A retrospective cohort analysis was performed of monochorionic twin pregnancies complicated by sFGR managed and delivered at a single tertiary center from 2015-2023. Patients undergoing laser treatment were excluded. All twin pairs underwent fetal echocardiogram by board-certified pediatric cardiologists at our center. Clinically relevant data was obtained from electronic medical records. Right and left myocardial performance index (MPI) were calculated incorporating ejection, isovolumetric contraction and isovolumetric relations times.

Results:
During the study period, 34 pairs of monochorionic twins were managed by our team. 2 patients were excluded as they did not undergo fetal echocardiograms as planned. The remaining 32 twin pairs underwent echocardiogram analysis at 20 weeks ± 6 days on average. Compared to the sFGR fetuses, AGA fetuses were more likely to have tricuspid regurgitation (TR, 38 vs 9%, p=0.02), right ventricular hypertrophy (RVH, 44 vs 9%, p=0.003), left ventricular hypertrophy (31 vs 3%, p=0.006), elevated right MPI (0.36 [0.26, 0.49] vs 0.29 [0.24, 0.35], p=0.03) and elevated left MPI (0.32 [0.29, 0.47] vs 0.29 [0.25, 0.35], p=0.02). No difference was noted in cardiac output (534 [483, 596] vs 522mL/min  [447, 596], p=0.41). At birth, 40% (6/15) of AGA fetuses with abnormal fetal echocardiograms, had RVH and TR compared to 25% (1/4) of sFGR fetuses.


Conclusion:
In this cohort of expectantly managed monochorionic twins complicated by sFGR, AGA twins were noted to have findings consistent with hemodynamic changes which could reflect cardiac overload in the perinatal period. Further assessment of neonatal and pediatric outcomes is needed to determine the long-term implications of these sonographic findings.