Background: Left ventricular noncompaction (LVNC) is characterized by excessive trabeculations of the LV and may be associated with reduced systolic function or severe adverse outcomes. Several aspects remain to be elucidated; there is controversy to whether LVNC cardiomyopathy is a distinct cardiomyopathy caused by failure of the spongy fetal myocardium to condense during fetal development or acquired later in life as a morphological trait associated with other types of cardiomyopathy; the prevalence in unselected populations is unknown and the distinction between normal variation and pathology remains to be defined. In this study, we aimed to determine the prevalence of LVNC and the association to LV systolic function in a large, population-based cohort of neonates. In addition, we assessed the normal ratio of noncompact to compact (NC:C) myocardium in 150 healthy neonates. Methods: Echocardiographic data were prospectively collected in the population study Copenhagen Baby Heart Study. The ratio of NC:C was measured in 12 ventricular segments. LVNC was defined as NC:C ≥2 in at least one segment. Neonates with LVNC were matched 1:10 to controls on sex, gestational age, and weight and age at the examination day. Results: In total, 25 590 neonates (52% males, median age 11 [interquartile range, 7–15] days) underwent echocardiography. Among 21 133 with satisfactory visualization of ventricular segments, we identified a prevalence of LVNC of 0.076% (95% CI, 0.047–0.123). LV ejection fraction was lower in neonates with LVNC compared with matched controls (median 49.5 versus 59.0%; P <0.0001). In neonates with otherwise healthy hearts, the median NC:C ratio ranged from 0.0 to 0.7 and the 99th percentiles from 1.0 to 1.9 for each of the 12 segments. Conclusions: The prevalence of LVNC based on neonatal echocardiography was 0.076%. LVNC was associated with lower LV systolic function. The findings in normal newborns support the cutoff NC:C ≥2 as an appropriate diagnostic criterion. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02753348.

Introduction Left ventricular non-compaction (LVNC) is characterized by excessive trabeculations of the left ventricular wall. LVNC may be associated with reduced systolic function but is also found in individuals with normal ventricular function. It is debated whether LVNC is only congenital or may develop later in life. The clinical importance and heredity of LVNC with normal systolic function is unclear. Purpose We aimed to describe the echocardiographic development of the left ventricular function and LVNC pattern in children with LVNC, diagnosed at birth, at follow-up at the age of 2–4 years compared to matched controls. Additionally, we aimed to describe the prevalence of LVNC in first-degree relatives. Methods A follow-up transthoracic echocardiography was performed in children at 2–4 years of age, diagnosed with LVNC at birth (&lt;30 days) as part of a large population study of newborns (n&gt;25,000). Cases were matched 1:4 to controls on mother's age at delivery, parity, and age of the child at follow-up. First-degree relatives (parents, siblings and half-siblings) of cases and controls were also offered inclusion. LVNC was defined as a ratio of non-compact to compact myocardium of ≥2 in at least one left ventricular segment measured in end-diastole perpendicular to the left ventricular cavity. Results 13 of the 16 children diagnosed with LVNC at birth (median age 3 (interquartile range (IQR) 3–4) years, 77% male) and 52 children without LVNC at birth (age 4 (IQR 3–4) years, 88% male) was reevaluated as well as 36 first-degree relatives of children with LVNC (age 30 (IQR 4–37) years, 44% male) and 136 first-degree relatives of children without LVNC (age 32 (IQR 10–38) years, 50% male). In probands, the number of segments fulfilling criteria (8% vs. 13%, p=0.4) and systolic function, measured as fractional shortening (FS), were unchanged from birth to follow-up, and within normal range (29% vs. 30%, p=0.34). However, at follow-up, FS was significantly lower in probands compared with matched controls (30% vs. 33%, p&lt;0.001). Criteria of LVNC was fulfilled in 11 out of 36 (31%) first-degree relatives to probands, whereas none of the first-degree relatives of children without LVNC fulfilled criteria of LVNC (p&lt;0.001). FS was significantly lower in first-degree relatives of probands fulfilling criteria of LVNC compared to first-degree relatives of matched controls (30% vs. 32%, p=0.01). Conclusion Children with LVNC diagnosed neonatally as part of a population study still had a reduced systolic function when compared to controls but showed no further progression of left ventricular dysfunction or extent of trabeculation at the age of 2–4 years. One third of first-degree relatives to children diagnosed with LVNC with a preserved systolic function, fulfilled criteria for LVNC and had reduced systolic function compared to controls. These findings strongly support family-screening and clinical follow-up of children with LVNC. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Novo Nordisk FoundationHerlev-Gentofte Hospital Internal Funding

Introduction: Left ventricular non-compaction (LVNC) is characterized by excessive trabeculations of the left ventricular wall and may be associated with reduced systolic function. It is debated whether LVNC is congenital or may develop later as part of other cardiomyopathies. The clinical importance and heredity of LVNC with normal systolic function is unclear. We aimed to describe the cardiac development in children with LVNC from birth to 2-4 years of age, compared to matched controls. Additionally, we aimed to describe the prevalence of LVNC in first-degree relatives. Methods: A follow-up transthoracic echocardiography was performed in children at 2-4 years of age diagnosed with LVNC at birth (<30 days) in the Copenhagen Baby Heart Study. Cases were matched to controls on mothers age at delivery, parity, and age of child at follow-up. First-degree relatives (parents, siblings and half-siblings) were also included. LVNC was defined as a non-compact to compact ratio of myocardium of ≥2 in at least one left ventricular segment, measured in 24 segments in end-diastole perpendicular to the left ventricular cavity as previously suggested. Results: Of the 16 children diagnosed with LVNC at birth, 10 have been reevaluated (age 3.5 (interquartile range (IQR) 3, 4) years, 80% male) together with 20 matched controls (age 4 (IQR 3, 4) years, 70% male), 29 first-degree relatives in case group (age 29 (IQR 4, 35) years, 45% male) and 55 first-degree relatives in control group (age 32 (IQR 11, 36) years, 51% male). In probands, the extent of trabeculation (13% vs. 12%, p=0.97) and fractional shortening (FS) (29% vs. 31%, p=0.24) were unchanged from birth to follow-up. At follow-up, the median left ventricular FS was significantly lower in probands compared to matched controls (31% vs. 33%, p=0.03). Ten (35%) first-degree relatives to probands fulfilled criteria for LVNC compared to 0 (0%) of first-degree relatives to controls (p<0.001). Conclusions: Children with LVNC diagnosed neonatally as part of a population study had no further progression of left ventricular dysfunction or extent of trabeculation at the age of 2-4 years, but systolic function was reduced compared to matched controls. One third of first-degree relatives to children with LVNC fulfilled criteria for LVNC.

Aims Wolff–Parkinson–White (WPW) syndrome is a conduction disorder characterized by an accessory electrical pathway between the atria and ventricles, which may predispose to supraventricular tachycardia (SVT) and sudden cardiac death. It can be seen as an isolated finding or associated with structural heart disease. Our aims were to determine the prevalence of a WPW pattern in a large and unselected cohort of neonates and to describe the electro- and echocardiographic characteristics as well as the natural history during early childhood. Methods and results Electrocardiograms and echocardiograms of neonates (aged 0–30 days) from a large, prospective, population-based cohort study were included. Neonates with a WPW pattern were identified and matched 1:4 to controls. Localization of the accessory pathway was assessed by different algorithms. Among 17 489 neonates, we identified 17 (76% boys) with a WPW pattern consistent with a prevalence of 0.1%. One neonate had moderate mitral regurgitation while other echocardiographic parameters were similar between cases and controls (all P &gt; 0.05). The accessory pathways were primarily predicted to be left-sided. At follow-up (available in 14/17 children; mean age 3.2 years) the pre-excitation pattern persisted in only four of the children and none of the children had experienced any episodes of SVT. Conclusion The prevalence of a WPW pattern in our cohort of unselected neonates was 0.1%. The WPW pattern was more frequent in boys and generally not associated with structural heart disease, and the accessory pathways were primarily left-sided. At follow-up, the WPW pattern had disappeared in most of the children suggesting either an intermittent nature or that normalization occurs. Clinical Trial Registration Copenhagen Baby Heart, NCT02753348.