Fetal hypoplastic left heart syndrome: key factors shaping prognosis

The purpose of the study is to estimate factors affecting survival in prenatally diagnosed hypoplastic left heart syndrome (HLHS) and echocardiographic features predicting poor prognosis and early neonatal death.

This study was designed as a retrospective cohort study. Cases of hypoplastic left heart syndrome diagnosed in the prenatal period between 2014 and 2023 were extracted from electronic medical records. Demographic data, echocardiographic features, results of genetic testing, pregnancy outcomes, and postnatal outcomes were analyzed.

Eighty-three prenatally diagnosed fetal HLHS cases were analyzed. Overall, survival during the study period was 26.5 %, and survival among live births was 35.4 %. Survival analysis has shown that the majority of deaths occurred during the neonatal period. Out of 62 live births, 47 had Norwood procedures, six had balloon procedures and three had hybrid procedures. Eleven out of 47 who had the Norwood procedures went on to have a Glenn operation, and only three had full Fontan palliation. The presence of additional extra-cardiac anomaly, need for extracorporeal membrane oxygenation (ECMO), bidirectional flow at pulmonary veins on color Doppler, and low birth weight are associated with survival and early neonatal death. Tricuspid regurgitation, restrictive foramen ovale, and fetal growth restriction (FGR) are not associated with survival. HLHS evolved from critical aortic stenosis has better survival rates.

Extra-cardiac anomaly, need for ECMO, bidirectional flow at pulmonary veins, and low birth weight were negatively associated with survival and early neonatal death. The survival rate was higher among HLHS cases that had evolved from critical aortic stenosis.