Hypertrophic cardiomyopathy in children has diverse causes. Mitochondrial diseases, a rare aetiology leading to cardiomyopathy in 20–40% of affected children, predominantly present as hypertrophic cardiomyopathy. Diagnosis is challenging due to inconsistent genotype-phenotype correlation, resulting in various clinical presentations. We present a case of a one-month-old infant with severe hypertrophic cardiomyopathy and cardiac tamponade. Genetic diagnosis revealed a Valyl-tRNA synthetase 2 (VARS2) gene mutation, linking it to mitochondrial encephalopathy-cardiomyopathy. This case highlights novel variants and expands the understanding of hypertrophic cardiomyopathy aetiology in infants.

Noonan syndrome is a multi-system genetic disorder and patients may suffer from hypertrophic cardiomyopathy. Previous studies have identified electrocardiographic features that may support a diagnosis of Noonan syndrome. In this two-centre retrospective study, we analysed typical Noonan syndrome-related electrocardiographic features in 30 patients with Noonan syndrome with hypertrophic cardiomyopathy and compared these with the electrocardiographic features in 15 children with sarcomeric hypertrophic cardiomyopathy. Typical Noonan syndrome-related electrocardiographic features are a negative aVF, small left precordial R-waves, large right precordial S-waves, and abnormal Q-wave. We also analysed electrocardiographic features of hypertrophic cardiomyopathy: ST-segment abnormalities and T-wave abnormalities. A negative aVF was seen in 83% of patients with Noonan syndrome-related hypertrophic cardiomyopathy in contrast to 27% of patients with primary sarcomeric hypertrophic cardiomyopathy (p < 0.001). An extreme QRS axis in the north-west was seen only in patients with Noonan syndrome-related hypertrophic cardiomyopathy. This QRS axis deviation is likely to be determined by the Noonan syndrome-related hypertrophic cardiomyopathy and not by the type of hypertrophic cardiomyopathy. There were no differences between the two groups in the frequency of large right precordial S-waves and small R-waves in the left precordial leads V5 and V6. However, an abnormal R/S ratio was more often seen in patients with Noonan syndrome-related hypertrophic cardiomyopathy (p < 0.001). Pathologic Q-waves were seen statistically more frequently in patients with sarcomeric hypertrophic cardiomyopathy (p = 0.009). The occurrence of ST-segment and T-wave pathology did not statistically differ between the two groups. Electrography can be of use in differentiating sarcomeric hypertrophic cardiomyopathy from Noonan syndrome-related hypertrophic cardiomyopathy.

Sudden cardiac death is the most common mode of death during childhood and adolescence in hypertrophic cardiomyopathy, and identifying those individuals at highest risk is a major aspect of clinical care. The mainstay of preventative therapy is the implantable cardioverter-defibrillator, which has been shown to be effective at terminating malignant ventricular arrhythmias in children with hypertrophic cardiomyopathy but can be associated with substantial morbidity. Accurate identification of those children at highest risk who would benefit most from implantable cardioverter-defibrillator implantation while minimising the risk of complications is, therefore, essential. This position statement, on behalf of the Association for European Paediatric and Congenital Cardiology (AEPC), reviews the currently available data on established and proposed risk factors for sudden cardiac death in childhood-onset hypertrophic cardiomyopathy and current approaches for risk stratification in this population. It also provides guidance on identification of individuals at risk of sudden cardiac death and optimal management of implantable cardioverter-defibrillators in children and adolescents with hypertrophic cardiomyopathy.

A 14-year-old previously healthy female presented with chest pain and dyspnoea for 2 days in the setting of a recent upper respiratory infection. She had elevated inflammatory markers and troponin, resulting in the diagnosis of acute myocarditis. Transthoracic echocardiography demonstrated mild systolic dysfunction and a moderate pericardial effusion. Additionally, her echocardiogram showed concentric left ventricular hypertrophy raising concern for hypertrophic cardiomyopathy. She was treated with intravenous immunoglobulin. Serial echocardiograms revealed rapid resolution of her ventricular hypertrophy. Cardiac magnetic resonance confirmed the diagnosis of myocarditis.

Although hypertrophic cardiomyopathy has a reported prevalence of 1/500, compound, double, and triple mutations are infrequent. There is phenotypic variation between individuals with HCM, making disease course difficult to predict. There is some debate as to whether multiple mutations confer a worse prognosis and the extent to which the mutations affect an individual’s prognosis. We report a case of homozygous MYBPC3 mutations in a 2-year-old presenting with aborted sudden cardiac death and a severe form of hypertrophic cardiomyopathy.

In contrast to hypertrophic cardiomyopathy caused by maternal diabetes, neonatal mitochondrial cardiomyopathy is rare and has a poor prognosis. We report an infant born to a mother with maternal diabetes with persistent ventricular hypertrophy, who was diagnosed with mitochondrial disease associated with m.3243A>G mutation in a mitochondrial tRNA leucine 1 gene. The hypertrophic cardiomyopathy was his initial and only clinical presentation.

Danon disease is a rare and fatal disease caused by a mutation in the lysosome-associated membrane protein 2 gene. Impaired intracellular autophagy causes lysosomal vacuoles to accumulate mainly in myocardial and skeletal muscle cells, leading to hypertrophic cardiomyopathy, skeletal myopathy, and varying degrees of intellectual disability. Two distinct childhood presentations of Danon disease are described in this report.

Nicolaides–Baraitser syndrome is a rare, neuro-developmental disorder caused by heterozygous pathogenic variants in the SMARCA2 gene, involved with chromatin regulation. Cardinal features include intellectual disability, short stature, microcephaly, triangular facies, sparse hair, brachydactyly, prominent interphalangeal joints and seizures. Genetic testing demonstrated a loss within SMARCA2 at 9p24.3 inclusive of basepairs 2094861_2141830 (hg19) in our patient. This case highlights a child with Nicolaides–Baraiter syndrome, a SMARCA2 gene deletion and a novel association of hypertrophic obstructive cardiomyopathy.

Ebstein malformation of tricuspid valve is a congenital disease of tricuspid valve with associated right ventricular cardiomyopathy. Hypertrophic cardiomyopathy is a form of inherited left ventricular cardiomyopathy caused by sarcomeric protein gene mutations with inherent risks of sudden cardiac death. Here we report a rare case with co-occurrence of Ebstein malformation of tricuspid valve and hypertrophic cardiomyopathy in a young patient.

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

A case of hypertrophic cardiomyopathy in the transition from childhood to adulthood, which was low risk by the conventional risk assessment model, medium risk by the adult risk prediction model, and high risk by the paediatric risk prediction model, was inserted an implantable cardioverter-defibrillator. Three years post-implantation, the patient was resuscitated with an appropriate discharge of cardioverter-defibrillator.

We present the rare case of lipomatous atrial septal hypertrophy associated with adrenocorticotropin hormone therapy in an infant with West syndrome, highlighting their relatively benign nature and good prognosis in children, and the relevance of the differential diagnosis with more dangerous cardiac masses in order to avoid aggressive diagnostic and therapeutic interventions.

Intracoronary wave intensity analysis in hypertrophic cardiomyopathy has shown a large backward compression wave due to compressive deformation of the intramyocardial coronary arteries in systole. The authors describe the angiographic evidence of this backward compression wave, which has not been described in this physiological context and can be a marker of poor prognosis.