Impact of gestational age of onset of fetal atrial restriction on postnatal outcomes in hypoplastic left heart syndrome

BACKGROUND: Patients with hypoplastic left heart syndrome who develop a restrictive atrial septum prenatally have higher rates of postnatal mortality compared to those without atrial restriction. It is not understood whether the gestational age at which restriction becomes apparent echocardiographically impacts clinical outcomes. METHODS: A single-centre, retrospective cohort study was performed, including 196 patients with hypoplastic left heart syndrome from 2008 to 2022. A restrictive atrial septum was diagnosed based on fetal echocardiographic findings of an intact atrial septum, antegrade:retrograde pulmonary vein Doppler velocity time integral ratio <3, and/or the presence of a decompressing vein. Patients were grouped as follows: 1. Without Restriction, 2. Early Restriction (<30 weeks' gestation), and 3. Late Restriction (≥30 weeks' gestation), based on the gestational age at which diagnostic criteria for restriction were met. Comparative postnatal overall survival and transplant-free survival analyses were performed using the Kaplan-Meier method. RESULTS: = 7) and the group without atrial restriction (40%). Similarly, transplant rates were higher in the Early group (23%) compared to the Late group (14%) and those without restriction (14%). Overall survival and transplant-free survival were not statistically different among the groups. CONCLUSIONS: While not statistically significant in this cohort with a small number of patients with atrial restriction, our data suggest that patients with hypoplastic left heart syndrome who meet diagnostic criteria for atrial restriction later in gestation may have outcomes more similar to those without atrial restriction.