Congenital diaphragmatic hernia with heart defect has a high risk for hypoplastic left heart syndrome and major extra‐cardiac malformations: 10‐year national cohort from Finland

Introduction Congenital diaphragmatic hernia (CDH) has a well‐known risk of congenital heart defects with poor prognosis. This study was conducted to determine the national total prevalence and prenatal detection rates of CDH with heart defects and its association with major extra‐cardiac malformations and to further evaluate the impact of the heart defect severity on survival. Material and methods A 10‐year national cohort was derived from four national registries, including live births, stillbirths, and terminations of pregnancy for fetal anomalies. The study cohort was sorted according to cardiac defect severity. Results The total prevalence of CDH with heart defects was 0.6/10 000 births and live birth prevalence 0.3/10 000 live births. Of 145 cases with CDH, 37 (26%) had a concurrent heart defect. The overall prenatal detection rate of heart defects was 41%. The total prevalence (483/10 000) and live birth prevalence (500/10 000) of hypoplastic left heart syndrome were 124 and 250 times higher than in the general population in Finland, respectively. Additional major extra‐cardiac malformations were found in 68% of cases. The survival rate for CDH with major heart defects was 11 and 38% with minor heart defects. Conclusions The total prevalence of hypoplastic left heart syndrome was significantly higher in CDH patients than in the general population in Finland. Prenatal detection rate for heart defects in CDH patients was 41%. Major extra‐cardiac malformations were more common than previously reported. The prognosis of CDH with major heart defects remained poor.