Kleefstra syndrome (KS), often diagnosed in early childhood, is a rare genetic disorder due to haploinsufficiency of EHMT1 and is characterized by neuromuscular and intellectual developmental abnormalities. Although congenital heart disease (CHD) is common, the prevalence of arrhythmias and CHD subtypes in KS is unknown. Inspired by a novel case series of KS patients with atrial tachyarrhythmias in the USA, we evaluate the two largest known KS registries for arrhythmias and CHD: Radboudumc (50 patients) based on health record review at Radboud University Medical Center in the Netherlands and GenIDA (163 patients) based on worldwide surveys of patient families. Three KS patients (aged 17-25 years) presented with atrial tachyarrhythmias without manifest CHD. In the international KS registries, the median [interquartile range (IQR)] age was considerably younger: GenIDA/Radboudumc at 10/13.5 (12/13) years, respectively. Both registries had a 40% prevalence of cardiovascular abnormalities, the majority being CHD, including septal defects, vascular malformations, and valvular disease. Interestingly, 4 (8%) patients in the Radboudumc registry reported arrhythmias without CHD, including one atrial fibrillation (AF), two with supraventricular tachycardias, and one with non-sustained ventricular tachycardia. The GenIDA registry reported one patient with AF and another with chronic ectopic atrial tachycardia (AT). In total, atrial tachyarrhythmias were noted in six young KS patients (6/213 or 3%) with at least four (three AF and one AT) without structural heart disease. In addition to a high prevalence of CHD, evolving data reveal early-onset atrial tachyarrhythmias in young KS patients, including AF, even in the absence of structural heart disease.

To estimate the association between major types of congenital heart defects (CHD) and spontaneous preterm birth, and to assess the potential underlying mechanisms. This nationwide, registry-based study included a cohort of all singleton pregnancies in Denmark from 1997 to 2013. The association between CHD and spontaneous preterm birth was estimated by multivariable Cox regression, adjusted for potential confounders. The following potential mechanisms were examined: maternal genetics (sibling analyses), polyhydramnios, preterm prelabor rupture of membranes, preeclampsia, and indicators of fetal and placental growth. The study included 1 040 474 births. Compared with the general population, CHD was associated with an increased risk of spontaneous preterm birth, adjusted hazard ratio 2.1 (95% CI, 1.9-2.4). Several subtypes were associated with increased risks, including pulmonary stenosis combined with a septal defect, 5.2 (95% CI, 3.7-7.5); pulmonary stenosis or atresia, 3.1 (95% CI, 2.4-4.1); tetralogy of Fallot 2.5 (95% CI, 1.6-3.8); coarctation or interrupted aortic arch 2.2 (95% CI, 1.5-3.2); and hypoplastic left heart syndrome, 2.0 (95% CI, 1.0-4.1). Overall, preterm prelabor rupture of membranes mediated more than one-half of the association. Maternal genetics, polyhydramnios, or indicators of fetal or placental growth did not explain the reported associations. CHD, especially right ventricular outflow tract obstructions, were associated with an increased risk of spontaneous preterm birth. The risk was carried by the CHD and not by maternal genetics. Moreover, preterm prelabor rupture of membranes was identified as a potential underlying mechanism.

Objective To assess the spectrum of associated anomalies, the intrauterine course, postnatal outcome and management of fetuses with double outlet right ventricle (DORV). Methods All cases of DORV diagnosed prenatally over a period of 8 years were retrospectively collected in a single tertiary referral center. All additional prenatal findings were assessed and correlated with the outcome. The accuracy of prenatal diagnosis was assessed. Results Forty-six cases of DORV were diagnosed prenatally. The mean gestational age at first diagnosis was 21+4 weeks (range, 13-37). A correct prenatal diagnosis of DORV was made in 96.3% of the cases. If the relation of the great arteries, the position of the ventricular septal defect (VSD) and additional cardiac anomalies are taken into account, the prenatal diagnosis was correct in 92.6% of the cases. One case was postnatally classified as transposition of the great arteries with subpulmonary VSD and was excluded from further analysis. A total of 41 (91.1%) fetuses with DORV had major additional cardiac anomalies, 30 (66.7%) had extracardiac anomalies and 13 (28.9%) had chromosomal or syndromal anomalies. Due to their complex additional anomalies, five (11.1%) of our 45 fetuses had multiple malformations and were highly suspicious for non-chromosomal genetic syndromes, although molecular diagnosis could not be provided. Disorders of laterality occurred in 10 (22.2%) fetuses. There were 17 terminations of pregnancy (37.8%), two (4.4%) intrauterine and seven (15.6%) postnatal deaths. Nineteen of 22 (86.4%) live-born children with an intention to treat were alive at last follow-up. The mean follow-up among survivors was 32 months (range, 2-72). Of 21 children who had already undergone postnatal surgery, eight (38.1%) achieved biventricular repair and 13 (61.9%) received univentricular palliation. One recently born child is still waiting for surgery. All children predicted prenatally to need a single ventricle palliation, and all children predicted to achieve biventricular repair, ultimately received the predicted type of surgery. After surgery, 14 of 18 (77.8%) children were healthy without any impairment. Conclusion DORV is a rare and often complex cardiac anomaly that can be diagnosed prenatally with high precision. DORV is frequently associated with major additional anomalies, leading to a high intrauterine and postnatal loss rate due to terminations or declined postnatal therapy. Without additional anomalies, the prognosis is good, although approximately 60% of children will have single ventricle palliation.

Neurodevelopmental disorders are the most common and distressful comorbidities associated with congenital heart defects (CHD). Head circumference at birth (HC), a proxy for prenatal cerebral growth, is an established risk factor for neurodevelopmental disorders. In a nationwide cohort, we included all 924 422 liveborn Danish singletons, 1997 to 2011. CHD was present in 5519. The association between CHD and growth indices was analyzed by multivariable linear regression, adjusted for potential confounders. We report mean differences in gestational age-specific z scores in comparison with the general population. CHD was associated with lower HC z scores, -0.10 (95% confidence interval [CI], -0.13 to -0.08). Several CHD subtypes were associated with smaller HC, eg, hypoplastic left heart syndrome, -0.39 (95% CI, -0.58 to -0.21); common arterial trunk, -0.41 (95% CI, -0.74 to -0.09); and major ventricular septal defects, -0.25 (95% CI, -0.35 to -0.15). Other single-ventricle defects, transposition of the great arteries, tetralogy of Fallot, and anomalous pulmonary venous return, were also associated with smaller HC. Transposition of the great arteries was associated with smaller HC relative to birth weight, -0.26 (95% CI, -0.39 to -0.13). Major ventricular septal defects were associated with larger HC relative to birth weight. The results were consistent under various conditions, eg, when siblings of infants with CHD (n=5311) or infants with other major malformations (n=24 974) were used as the reference. Several subtypes of CHD were associated with smaller HC. The associations with major ventricular septal defects, common arterial trunk, and anomalous pulmonary venous return have not previously been described. Only infants with transposition of the great arteries had smaller HC relative to birth weight.