The impact of not having a ductus arteriosus on clinical outcomes in foetuses diagnosed with tetralogy of Fallot

BACKGROUND: Foetuses with simple tetralogy of Fallot almost universally have a patent ductus arteriosus. Two recently identified cases had an absent patent ductus arteriosus, requiring emergent intervention at birth. The objective of this study was to determine whether foetuses diagnosed with tetralogy of Fallot and no patent ductus arteriosus have poorer outcomes compared with those with tetralogy of Fallot+patent ductus arteriosus. METHODS: All foetal cases of tetralogy of Fallot between January, 2000 and 2012 were retrospectively identified from The Hospital for Sick Children (Toronto, Canada) database. Cases - tetralogy of Fallot+no patent ductus arteriosus confirmed on postnatal echo - and controls - tetralogy of Fallot+patent ductus arteriosus, matched for gestational age - were identified from prenatal records, and both clinical and echocardiographic data were reviewed. Optimal outcome was defined as valve-sparing repair with no residual lesions. Student's t-tests and Fisher's exact χ2 were used to compare groups. RESULTS: n=115 foetuses were diagnosed with tetralogy of Fallot: 11 (9%) had no patent ductus arteriosus, and were matched to 22 controls - mean gestational age at diagnosis 23.2±4.2 weeks, 23.4±6.6 weeks, respectively. Cases had a higher proportion of right aortic arches (64% versus 14%, p<0.001). Foetal and postnatal echocardiographic data did not reveal significant differences in branch pulmonary artery sizes, pulmonary valve sizes, or ventricular function. No differences were identified for cyanosis at birth (2/10 versus 7/20, p=0.67), or catheter intervention (5/10 versus 4/22, p=0.12). Optimal outcome rates were similar between cases and controls (4/11 (36%) versus 5/21 (24%), p=0.68). CONCLUSIONS: The patent ductus arteriosus does not appear to have an impact on clinical outcome in foetuses with tetralogy of Fallot.