Implications of right aortic arch prenatal diagnosis: the multicentric nationwide ARCADE cohort.

Objectives: This study aims to describe the various presentations of the prenatally diagnosed isolated right aortic arch (RAA), that is, without associated congenital heart defect and to evaluate the impact of prenatal diagnosis of isolated RAA in terms of postnatal outcome.

Method: In this multicentric retrospective study, from 2010 to 2019, all live births with a prenatal ultrasound diagnosis of isolated RAA were included, with a 1-year postnatal follow-up. The concordance between the different diagnostic steps (prenatal ultrasound, postnatal ultrasound and postnatal CT scan) was evaluated using Gwet's AC1 coefficient.

Results: A total of 309 cases of prenatally diagnosed RAA were analysed, most of which had a left ductus arteriosus (83%). The concordance between prenatal and postnatal ultrasound diagnosis was excellent regarding the RAA type (AC1=0.97, 95% CI=(0.94 to 0.99)). The rare discrepancies mainly involved non-diagnosed or misdiagnosed double aortic arch (2%). CT scan was performed in 108 neonates (35%) and the concordance between prenatal ultrasound and postnatal CT scan was good regarding the RAA diagnosis (AC1=0.80, 95% CI=(0.69 to 0.90)) but poor regarding the distribution of brachiocephalic vessels (AC1=0.21, 95% CI=(0.06 to 0.36)). An associated genetic anomaly was sought for in half of the cases and identified in 4% of the cohort. During the first year of life, 50 (18%) infants presented with vascular ring symptoms and 24 (8%) underwent aortic arch surgery.

Conclusion: This multicentric nationwide cohort of 309 prenatally diagnosed isolated RAA demonstrated the reliability of prenatal screening, highlighted the rare cases of discrepancies between prenatal and postnatal diagnosis and underlined the value of CT scan to improve the postnatal follow-up.

Trial registration number: NCT04029064.