Outcomes of single ventricle heart defects may be influenced by the morphological type of the hypoplastic ventricle. Recent multi-centre studies have targeted on outcomes of hypoplastic left heart syndrome with limited focus on outcomes of hypoplastic right heart syndrome. We aimed at studying the clinical outcomes of hypoplastic right heart syndrome in the recent era.

We performed a retrospective analysis of all hypoplastic right heart syndrome patients (n = 153) born between January 2010 and January 2023. Five-year transplant-free survival was compared with hypoplastic left heart syndrome patients without heterotaxy (n = 144) born during the same time.

Double-inlet left ventricle was the most common anatomic hypoplastic right heart syndrome subtype (n = 39, 25%). Twenty-six (17%) patients with hypoplastic right heart had associated heterotaxy. Five-year transplant-free survival was high for most groups (double inlet left ventricle: 100%, pulmonary atresia: 94%, Ebstein’s anomaly: 92%, tricuspid atresia: 90% respectively). The heterotaxy group had worse early outcomes with 3 deaths and 3 heart transplants, before Fontan completion. Heterotaxy was a significant risk factor for death/transplant prior to Fontan completion in hypoplastic right heart syndrome patients (p = 0.03). Patients with hypoplastic right heart syndrome with heterotaxy had significantly worse 5-year transplant-free survival (71%) when compared to hypoplastic right heart syndrome without heterotaxy (95%) and hypoplastic left heart syndrome without heterotaxy (75%), p < 0.001.

Hypoplastic right heart syndrome patients have excellent clinical outcomes and better early childhood survival than hypoplastic left heart syndrome in the current era, except when associated with heterotaxy. The survival advantage conferred by a single left ventricle appears to be negated by heterotaxy syndrome and should be strongly considered during caregiver counselling and medical decision-making.