The interesting study has limitations that put the results and their interpretation into perspective. m.3243A>G carriers should undergo prospective testing for multisystem disease to avoid missing subclinical multisystem involvement. m.3243A>G carriers with hypertrophic cardiomyopathy require long-term electrocardiogram recordings to determine whether implantable cardioverter defibrillator implantation is necessary or not. To assess the outcome of m.3243A>G carriers, knowledge of heteroplasmy rates and mtDNA copy numbers is required. It is tempting to assign pathogenicity when any pathogenic variant is seen with genotype-phenotype correlation. However, double hits are possible and if genetic information is to be used to screen or risk-stratify other family members, the standard of care would be to ensure that post-mortem genetic autopsy is performed for a panel of causative genes, and that an autopsy is done to exclude other causes of death, if possible.

We present a clinical case of a teenager in whom a Brugada syndrome electrical pattern was found which was finally diagnosed as a Brugada phenocopy due to a wrong setup of the high-pass filter on the electrocardiogram

Congenital Long QT Syndrome (LQTS) is a dangerous arrhythmic disorder that can be diagnosed in children with bradycardia. It is characterised by a prolonged QT interval and torsades de pointes that may cause sudden death. Long QT syndrome is an ion channelopathy with complex molecular and physiological infrastructure. Unlike the acquired type, congenital LQTS has a genetic inheritance and it may be diagnosed by syncope, stress in activity, cardiac dysfunction, sudden death or sometimes incidentally. Permanent pacemaker implantation is required for LQTS with resistant bradycardia even in children to resolve symptoms and avoid sudden death.

We report a 10-month-old girl with KCNT1 (c1420C > T; p. Arg474Cys, R474C) mutation-associated epileptic encephalopathy, systemic-to-pulmonary artery “collateralopathy”, and intermittent QTc prolongation. Spontaneous regression of systemic-to-pulmonary artery collateral-mediated left heart dilation was noted in this patient, a finding which was ominous as it heralded the onset of severe pulmonary hypertension. The structural and electrical phenotypic features of KCNT1 mutation-associated heart disease, including the novel findings noted in our patient, are discussed in detail.

We present the case of a 12-year-old boy with type 2 long QT syndrome in whom torsades de pointes was induced by an acute face immersion test. This test is feasible to predict cardiac events in adolescents with long QT syndrome.

In young patients with unexplained ventricular fibrillation, coronary occlusion may be missed by echocardiogram and misinterpreted by CT. We report two patients presenting with ventricular fibrillation and initially negative workup, later identified to have occlusion of left main coronary artery. We demonstrate the importance of angiography to rule out coronary occlusion in patients with unexplained ventricular fibrillation.

Second-generation antipsychotic medications (SGAs) have advanced the treatment of schizophrenia over the past 30 years. However, a number of potentially life-threatening cardiac side-effects associated with these treatments concern and can discourage prescribers from administering these evidence-based treatments. This review provides a practical, psychiatrist-oriented understanding of the relative frequencies, mechanisms, investigations and treatments associated with these cardiac toxicities. We aim to highlight that these are relatively rare complications of an effective class of drug and to promote the advantages of early involvement of cardiologists in the psychiatric multidisciplinary team to guide the investigation and management of these conditions.

The Wolff–Parkinson–White pattern refers to the electrocardiographic appearance in sinus rhythm, wherein an accessory atrioventricular pathway abbreviates the P-R interval and causes a slurring of the QRS upslope – the “delta wave”. It may be asymptomatic or it may be associated with orthodromic reciprocating tachycardia; however, rarely, even in children, it is associated with sudden death due to ventricular fibrillation resulting from a rapid response by the accessory pathway to atrial fibrillation, which itself seems to result from orthodromic reciprocating tachycardia. Historically, patients at risk for sudden death were characterised by the presence of symptoms and a shortest pre- excited R-R interval during induced atrial fibrillation <250 ms. Owing to the relatively high prevalence of asymptomatic Wolff–Parkinson–White pattern and availability of catheter ablation, there has been a need to identify risk among asymptomatic patients. Recent guidelines recommend invasive evaluation for such patients where pre-excitation clearly does not disappear during exercise testing. This strategy has a high negative predictive value only. The accuracy of this approach is under continued investigation, especially in light of other considerations: Patients having intermittent pre-excitation, once thought to be at minimal risk may not be, and the role of isoproterenol in risk assessment.

Hypertrophic cardiomyopathy is a common, inherited heart disease with a heterogeneous clinical presentation and natural history. Recently, advances in diagnosis and treatment options have been instrumental in decreasing the frequency of adverse clinical events; however, complete elimination of sudden cardiac death still remains an elusive gain. This article discusses several aspects of this condition in the young: epidemiology, clinical phenotypes, risk factors, prevention of sudden cardiac death, and risks of athletic participation.

Paediatric exercise stress testing has historically been used to assess the functional status of patients after repair of CHDs and to assess the efficacy of medical or device therapy in patients with arrhythmias. Exercise stress testing is one of very few hospital- or clinic-based tests that can assess the response of the cardiopulmonary system in an environment that simulates the body’s response to vigorous play and competitive sport. Exercise stress testing is therefore a useful modality in the assessment of child and athletes at risk for sudden cardiac death. The author discusses some cardiovascular maladies that can cause sudden cardiac death by utilising case illustrations as a learning tool.

Untreated congenital long QT syndrome may result in potentially lethal ventricular tachycardia. In the most common type, risk of such an event has been linked to exercise. This originally resulted in very restrictive guidelines for sports participation in affected individuals. Although the complex interactions of a specific genotype, modifying cofactors, and risk are only now being explored, scientific evidence based on clinical experience now suggests that in many instances such restrictive guidelines are unwarranted. In particular, patients with this condition who are compliant with β-blocker therapy and who have never had symptoms during exertion are now enjoying the benefits of athletic activity.

Most young patients with mild-to-moderate aortic stenosis show no symptoms, and sudden death appears only occasionally. We hypothesised that malignant ventricular arrhythmias could be responsible for the high incidence of sudden death in such patients. If multiple factors such as asymptomatic aortic stenosis in association with arrhythmia-provoking agents are involved, could it be sufficient to account for sudden unexpected death? In this study, eight cases of sudden death in young adults, with ages ranging from 22 to 36 years, who had never reported any symptoms that could be related to aortic stenosis, were investigated. Full autopsies were performed, and congenital aortic stenosis in all eight cases was confirmed. DNA testing for channelopathies was negative. Comprehensive toxicological analyses found an electrolyte imbalance, or non-toxic concentrations of amitriptyline, terfenadine, caffeine, and ethanol. Collectively, these results suggest that congenital asymptomatic aortic stenosis without cardiac hypertrophy in young adults is not sufficient to cause sudden death merely on its own; rather, an additional provoking factor is necessary. According to our findings, the provoking factor may be a state of physical or emotional stress, a state of electrolyte imbalance, or even taking a therapeutic dose of a particular drug.

Brugada syndrome is an inherited arrhythmogenic disorder, characterised by coved-type ST-segment elevation in the right precordial leads, and is associated with increased risk of sudden death. It is genetically and clinically heterogeneous, presenting typically in the fourth or fifth decade of life. The prevalence of Brugada syndrome in the paediatric population is low compared with the adult population. Interestingly, over the last several years, there has been growing evidence in the literature of onset of the disease during childhood. Most of the paediatric cases reported in the literature consist of asymptomatic Brugada syndrome; however, some patients manifest the disease at different regions of the cardiac conduction system at a young age. Early expression of the disease can be affected by multiple factors, including genetic substrate, hormonal changes, and still unknown environmental exposures. The initial manifestation of Brugada syndrome in children can include sinus node dysfunction and atrial arrhythmias. Brugada syndrome can also manifest as ventricular arrhythmias leading to sudden death at an early age. In symptomatic children, performance of the ajmaline test by an experienced team can be safely used as a diagnostic tool to unmask latent Brugada syndrome. Defining indications for an implantable cardioverter defibrillator in children with the diagnosis of Brugada syndrome remains challenging. Given the rarity of the syndrome in children, most paediatric cardiologists will only rarely see a young patient with Brugada syndrome and there is still no universal consensus regarding the optimal management approach. Care should be individualised according to the specific clinical presentation, taking into account the family history, genetic data, and the family’s specific preferences.