Prenatal Predictors of Early Intervention in Simple Tetralogy of Fallot: A Retrospective Multi-Centre Study

Prenatal predictors of early postnatal intervention in tetralogy of Fallot (ToF) remain uncertain. This study aimed to identify prenatal cardiac and non-cardiac predictors of disease severity associated with early intervention in ToF.

This retrospective cohort study included prenatally diagnosed infants with simple ToF who underwent cardiac surgery or catheter intervention in their first year in Aotearoa New Zealand and Australia 2010-2019. Fetal echocardiography measurements from 28 to 32 weeks of gestation and prenatally diagnosed genetic and extracardiac structural anomalies were recorded. Comparison was made between infants undergoing early (≤ 30 days) and later intervention.

Of 253 infants, 33 (13%) underwent an early intervention. Infants requiring early intervention had lower pulmonary valve (PV) Z-scores (-4.7 ± 2.2 vs. -2.6 ± 1.6; p < 0.0001) or abnormal ductus arteriosus (DA) flow (14/30 (47%) versus 20/158 (13%), p < 0.001). A PV Z-score ≤ -3.5 or abnormal flow in the DA strongly predicted the timing of intervention (sensitivity 79%, specificity 70%, AUC 0.81). There was no association between the presence of a genetic or extracardiac anomaly and the timing of cardiac intervention.

Early intervention in ToF can be predicted from fetal echocardiogram measurements, including a PV Z-score ≤ -3.5 or abnormal DA flow at 28-32 weeks gestation. These findings have implications for prenatal counselling and planning of prenatal obstetric care.