Childhood-onset hypertrophic cardiomyopathy research coming of age

This editorial refers to ‘Clinical characteristics and outcomes in childhood-onset hypertrophic cardiomyopathy’, by N.A. Marston et al., on page 1988 (http://dx.doi.org/10.1093/eurheartj/ehab148)

Prevention of sudden cardiac death in childhood-onset hypertrophic cardiomyopathy

BACKGROUND: Sudden cardiac death (SCD) is the most common cause of death in children with HCM. Although recent population-based studies have shown that SCD rates are lower than previously thought, it still occurs more frequently than in adult patients, highlighting the importance of accurate identification of those at risk. AIMS OF REVIEW: This review highlights risk factors for SCD in childhood HCM, current risk stratification guidelines, and novel personalized models for risk prediction. KEY SCIENTIFIC CONCEPTS OF REVIEW: The traditional approach to risk prediction in childhood-onset HCM, using cumulative risk factor thresholds and adopted by current international guidelines, has involved extrapolation of adult data, but recent evidence has demonstrated that this approach does not accurately discriminate high-risk from low-risk individuals. In response to this knowledge gap, novel pediatric-specific risk stratification models have been developed that allow calculation of individualized estimates of SCD risk and enable a personalized and shared decision-making approach to ICD implantation

Childhood Hypertrophic Cardiomyopathy: A Disease of the Cardiac Sarcomere

Hypertrophic cardiomyopathy is the second most common cause of cardiomyopathy presenting during childhood and whilst its underlying aetiology is variable, the majority of disease is caused by sarcomeric protein gene variants. Sarcomeric disease can present at any age with highly variable disease phenotype, progression and outcomes. The majority have good childhood-outcomes with reported 5-year survival rates above 80%. However, childhood onset disease is associated with considerable life-long morbidity and mortality, including a higher SCD rate during childhood than seen in adults. Management is currently focused on relieving symptoms and preventing disease-related complications, but the possibility of future disease-modifying therapies offers an exciting opportunity to modulate disease expression and outcomes in these young patients

Genetic testing for inheritable cardiac channelopathies

Cardiac channelopathies are linked to an increased risk of ventricular arrhythmia and sudden death. This article reviews the clinical characteristics and genetic basis of common cardiac ion-channel diseases, highlights some genotype–phenotype correlations, and summarizes genetic testing for inheritable cardiac channelopathies

Risk stratification in childhood hypertrophic cardiomyopathy

The true prevalence of hypertrophic cardiomyopathy (HCM) in childhood is unknown, but population-based studies have reported an annual incidence between 0.24–0.47 per 100,000 children. The aetiology of disease is more heterogeneous than that seen in adult populations, with up to 30% of patients having an inborn error of metabolism, malformation syndrome or neuromuscular syndrome. However, as in adults, most cases are caused by mutations in the cardiac sarcomere protein genes, even in young children. The long-term outcome of childhood HCM is highly variable and has been shown to depend partly on the age of presentation and underlying aetiology. Outside of infancy, the most frequent cause of mortality is sudden cardiac death (SCD), and one of the greatest challenges in managing young patients with HCM is identifying those at greatest risk of an arrhythmic event

Cardiovascular safety of growth hormone treatment in Noonan syndrome: real-world evidence

OBJECTIVE: To assess cardiovascular (CV) safety of growth hormone (GH) treatment in patients with Noonan syndrome (NS) in clinical practice. DESIGN: Two observational, multicentre studies (NordiNet® IOS and the ANSWER Program) evaluating long-term effectiveness and safety of GH in >38,000 paediatric patients, of which 421 had NS. METHODS: Serious adverse events, serious adverse reactions (SARs), and non-serious adverse reactions (NSARs) were reported by the treating physicians. CV comorbidities at baseline and throughout the studies were also recorded. RESULTS: The safety analysis set comprised 412 children with NS (29.1% females), with a mean (standard deviation) baseline age of 9.29 (3.88) years, treated with an average GH dose of 0.047 (0.014) mg/kg/day during childhood. CV comorbidities at baseline were reported in 48 (11.7%), most commonly pulmonary valve stenosis and atrial septal defects. Overall, 22 (5.3%) patients experienced 34 safety events. The most common were the NSARs: headache (eight events in seven patients) and arthralgia (five events in three patients). Two SARs occurred in one patient (brain neoplasm and metastases to spine). No CV safety events were recorded in patients with NS. Five CV comorbidities in five patients were reported after initiation of GH treatment: three cases of unspecified CV disease, one ruptured abdominal aortic aneurysm and one pulmonary valve stenosis. CONCLUSIONS: GH treatment had a favourable safety profile in patients with NS, including those with CV comorbidities. Prospective studies are warranted to systematically assess the safety of GH treatment in patients with Noonan syndrome and CV disease

Clinical significance of inferolateral early repolarisation and late potentials in children with Brugada Syndrome.

INTRODUCTION: The clinical utility of inferolateral early repolarisation (ER) and late potentials (LP) in children with Brugada Syndrome (BrS) has not been previously evaluated. The aim of this study was to determine the prevalence of electrocardiographic (ECG) abnormalities in children with BrS, and to investigate their relationship with clinical outcomes. METHODS: 43 patients with BrS and 47 controls aged ≤18 undergoing systematic clinical and ECG evaluation, including signal-averaged ECG (SAECG) and pharmacological provocation testing, between 2003 and 2019 were included. RESULTS: Four patients with BrS (9%) presented with a spontaneous type 1 Brugada pattern; the remaining 39 (91%) were diagnosed following ajmaline provocation testing. Twelve BrS patients (28%) had late potentials (LP) on SAECG compared to 1 (2%) in controls (p = 0.001). LP were more common in 5 patients with a high-risk phenotype (60% vs 24%) but this was not statistically significant. Twelve patients with BrS (28%) had inferolateral early repolarisation (ER) and 2 (5%) had fractionated QRS (f-QRS), but there were no statistically-significant differences with controls in these parameters. A significant arrhythmia (non-sustained ventricular tachycardia or atrial fibrillation) was seen in 4 patients (9%). CONCLUSIONS: This study shows a high prevalence of SAECG abnormalities in children with BrS compared with controls, but this was not significantly associated with a high-risk phenotype

Noncompaction Cardiomyopathy, Sick Sinus Disease, and Aortic Dilatation: Too Much for a Single Diagnosis?

HCN4 mutations have been reported in association with sick sinus syndrome. A more complex phenotype, including noncompaction cardiomyopathy and aortic dilatation, has recently emerged. We report 3 family members with the pathogenic p.Gly482Arg variant, emphasizing the importance of considering HCN4 mutations when this combination of features is encountered in clinical practice. (Level of Difficulty: Advanced.