Fetal cardiac axis in tetralogy of Fallot: associations with prenatal findings, genetic anomalies and postnatal outcome

ABSTRACT Objective To compare prenatal findings, associated genetic anomalies and postnatal outcome in fetuses with tetralogy of Fallot (TOF) with normal cardiac axis (CAx) and those with abnormal CAx. Methods In this retrospective cohort study, 85 cases diagnosed with TOF by prenatal ultrasound at our clinic between 2005 and 2015 were reviewed. Follow‐up ultrasound and postnatal outcome were available for 68 cases. One case complicated with absent pulmonary valve syndrome and a further seven cases diagnosed postnatally with anomalies other than TOF were excluded from the study. The remaining 60 cases of postnatally confirmed TOF were divided according to CAx into two groups: those with normal CAx ( n = 33) and those with abnormal CAx ( n = 27). CAx was defined as the angle between the interventricular septum and midline of the fetal thorax at the level of the four‐chamber view. CAx > 65° or < 25° was considered abnormal. Prenatal sonographic findings, associated genetic anomalies and postnatal outcome were compared between the two groups. Results Fetuses with TOF and abnormal CAx were more likely to have pulmonary atresia (40.7% vs 15.2%; P = 0.026) and right‐sided aortic arch (48.1% vs 21.2%; P = 0.028) than those with normal CAx. Postnatal death occurred in 30.4% of infants with abnormal CAx vs 6.5% with normal CAx ( P = 0.028). Incidence of tested genetic anomalies was similar between the two groups. Conclusion In fetuses with TOF, abnormal CAx is associated with the presence of pulmonary atresia, right‐sided aortic arch and a higher risk of postnatal death. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.