In Children and Adolescents From Brugada Syndrome-Families, Only SCN5A Mutation Carriers Develop a Type-1 ECG Pattern Induced By Fever

Screening, diagnosis and follow-up of Brugada syndrome in children: a Dutch expert consensus statement

Brugada syndrome (BrS) is a rare inherited arrhythmia syndrome. Affected children may experience life-threatening symptoms, mainly during fever. The percentage of SCN5A variant carriers in children is higher than in adults. Current diagnostic and follow-up policies for children with (a family history of) BrS vary between centres. Here, we present a consensus statement based on the current literature and expert opinions to standardise the approach for all children with BrS and those from BrS families in the Netherlands. In summary, BrS is diagnosed in patients with a spontaneous type 1 electrocardiogram (ECG) pattern or with a Shanghai score ≥ 3.5 including ≥ 1 ECG finding. A sodium channel-blocking drug challenge test should only be performed after puberty with a few exceptions. A fever ECG is indicated in children with suspected BrS, in children with a first-degree family member with definite or possible BrS according to the Shanghai criteria with a SCN5A variant and in paediatric SCN5A variant carriers. In-hospital rhythm monitoring during fever is indicated in patients with an existing type 1 ECG pattern and in those who develop such a pattern. Genetic testing should be restricted to SCN5A. Children with BrS and children who carry an SCN5A variant should avoid medication listed at www.brugadadrugs.org and fever should be suppressed. Ventricular arrhythmias or electrical storms should be treated with isoproterenol infusion.

Clinical characteristics and electrophysiologic properties of SCN5A variants in fever-induced Brugada syndrome

BACKGROUND

Brugada syndrome (BrS) is a severe inherited arrhythmia syndrome that can be unmasked by fever.

METHODS

A multicentre clinical analysis was performed in 261 patients diagnosed with fever-induced BrS, including 198 (75.9%) and 27 (10.3%) patients who received next-generation genetic sequencing and epicardial arrhythmogenic substrate (AS) mapping, respectively.

FINDINGS

In fever-induced BrS patients, pathogenic or likely pathogenic (P/LP) SCN5A variant carriers developed fever-induced BrS at a younger age, and more often in females and those of Caucasian descent. They exhibited significant electrophysical abnormalities, including a larger epicardial AS area, and more prolonged abnormal epicardial electrograms. During a median follow-up of 50.5 months (quartiles 32.5-81.5 months) after the diagnosis, major cardiac events (MCE) occurred in 27 (14.4%) patients. Patients with P/LP SCN5A variants had a higher ratio of MCE compared with the rest. Additionally, history of syncope, QRS duration, and Tpe interval could also predict an increased risk for future MCE according to univariate analysis. Multivariate analysis indicated that only P/LP SCN5A variants were independent significant predictors of MCE. Computational structural modelling showed that most variants are destabilizing, suggesting that Nav1.5 structure destabilization caused by SCN5A missense variants may contribute to fever-induced BrS.

INTERPRETATION

In our cohort, P/LP SCN5A variant carriers with fever-induced BrS are more prevalent among patients of Caucasian descent, females, and younger patients. These patients exhibit aggressive electrophysiological abnormalities and worse outcome, which warrants closer monitoring and more urgent management of fever.

FUNDING

The current work was supported by the National Natural Science Foundation Project of China (Nos. 82270332 & 81670304), The Fundamental Research Funds for the Central Universities of China - Independent Research Project of Wuhan University (No. 2042022kf1217) from China; the National Institutes of Health of USA [NIH R56 (HL47678), NIH R01 (HL138103), and NIH R01 (HL152201)], the W. W. Smith Charitable Trust and the Wistar and Martha Morris Fund, Sharpe-Strumia Research Foundation, the American Heart Association Postdoctoral Fellowship (20POST35220002) from United States; the Netherlands CardioVascular Research Initiative: the Dutch Heart Foundation, Dutch Federation of University Medical Centers, the Netherlands Organization for Health Research and Development, and the Royal Netherlands Academy of Sciences (PREDICT2) from the Netherlands.

Sudden Cardiac Arrest in the Paediatric Population

Sudden cardiac arrest in the young is a rare event with a range of potential causes including cardiomyopathies, ion channelopathies, and autonomic nervous system dysfunction. Investigations into the cause involve a multidisciplinary team, including cardiologists, geneticists, and psychologists. In addition to a detailed medical history, family history and circumstances surrounding the event are important in determining the cause. Clinical investigations including an electrocardiogram are fundamental in diagnosis and should be interpreted cautiously because some children may have atypical presentations and an evolving phenotype. The potential for misdiagnosis exists that could lead to incorrect long-term management strategies. If an inherited condition is suspected, genetic testing of the patient and cascade screening of family members is recommended with genetic counselling and psychological support. Medical management is left to the treating physician acknowledging that a clear diagnosis cannot be made in approximately half of cases. Secondary prevention implantable defibrillators are widely deployed but can be associated with complications in young patients. A plan for safe return to activity is recommended along with a proper transition of care into adulthood. Broad screening of the general population for arrhythmia syndromes is not recommended; preventative measures include screening paediatric patients for risk factors by their primary care physician. Several milestone events or activities that take place in youth could be used as opportunities to promote safety. Further work into risk stratification of this paediatric population through patient registries and greater awareness of cardiopulmonary resuscitation and automated external defibrillator use in saving lives is warranted.

Brugada pattern revealed during SARS-COV-2-related multi-systemic inflammatory syndrome in a 6-year-old child

Rhythm abnormalities are rare during COVID-19-related multisystem inflammatory syndrome in children (MIS-C). We are reporting the detection of type I Brugada pattern in a 6-year-old child with MIS-C. Following the start of treatment (systemic steroids and immunoglobulins), a gradual evolution of cardiac rhythm up to normalisation was observed, concomitantly with a progressive reduction of inflammatory markers.

Pregnancy in women with Brugada syndrome: Is there an increased arrhythmia risk? A case-series report

INTRODUCTION

In some rare arrhythmia syndromes, arrhythmia risk in female patients increases during pregnancy, necessitating extra controls. We wanted to evaluate if the increased risk for arrhythmia during pregnancy applies in women with Brugada syndrome and their potentially affected fetuses.

METHODS

A comprehensive literature search was performed on PubMed (MeSH search terms "Brugada syndrome," "pregnancy," "parturition," "labor," "delivery," "fetal death," and "stillbirth").

RESULTS

Overall, six case reports with a total of six patients were identified. Of these six patients (three carriers of an SCN5A variant, three not tested), two women (both with unknown SCN5A status), developed severe cardiac events during pregnancy. The first patient, with a previous history of aborted sudden cardiac arrest at the age of 12 years, developed ventricular fibrillation (VF), while the other was diagnosed with Brugada syndrome postpartum because of nocturnal agonal respiration during pregnancy.

CONCLUSION

These (limited, heterogenous) cases suggest that women with Brugada syndrome (and their possibly affected fetuses), might have an overall low tendency to develop arrhythmias during pregnancy, but important data on risk factors (SCN5A status) are lacking. Arrhythmia risk during pregnancy seems to increase in probands and those who have previously experienced cardiac events. We suggest the use of risk stratification in these women to improve patient care, lower the emotional stress and physical burden for the pregnant mother, and lower health costs. Furthermore, we plead for SCN5A analysis in all these women for use of risk stratification and to enable cascade screening especially for specialized care in children carrying an SCN5A mutation.

Towards Mutation-Specific Precision Medicine in Atypical Clinical Phenotypes of Inherited Arrhythmia Syndromes

Most causal genes for inherited arrhythmia syndromes (IASs) encode cardiac ion channel-related proteins. Genotype-phenotype studies and functional analyses of mutant genes, using heterologous expression systems and animal models, have revealed the pathophysiology of IASs and enabled, in part, the establishment of causal gene-specific precision medicine. Additionally, the utilization of induced pluripotent stem cell (iPSC) technology have provided further insights into the pathophysiology of IASs and novel promising therapeutic strategies, especially in long QT syndrome. It is now known that there are atypical clinical phenotypes of IASs associated with specific mutations that have unique electrophysiological properties, which raises a possibility of mutation-specific precision medicine. In particular, patients with Brugada syndrome harboring an SCN5A R1632C mutation exhibit exercise-induced cardiac events, which may be caused by a marked activity-dependent loss of R1632C-Nav1.5 availability due to a marked delay of recovery from inactivation. This suggests that the use of isoproterenol should be avoided. Conversely, the efficacy of β-blocker needs to be examined. Patients harboring a KCND3 V392I mutation exhibit both cardiac (early repolarization syndrome and paroxysmal atrial fibrillation) and cerebral (epilepsy) phenotypes, which may be associated with a unique mixed electrophysiological property of V392I-Kv4.3. Since the epileptic phenotype appears to manifest prior to cardiac events in this mutation carrier, identifying KCND3 mutations in patients with epilepsy and providing optimal therapy will help prevent sudden unexpected death in epilepsy. Further studies using the iPSC technology may provide novel insights into the pathophysiology of atypical clinical phenotypes of IASs and the development of mutation-specific precision medicine.

Update on Genetic Basis of Brugada Syndrome: Monogenic, Polygenic or Oligogenic?

Brugada syndrome is a rare inherited arrhythmogenic disease leading to ventricular fibrillation and high risk of sudden death. In 1998, this syndrome was linked with a genetic variant with an autosomal dominant pattern of inheritance. To date, rare variants identified in more than 40 genes have been potentially associated with this disease. Variants in regulatory regions, combinations of common variants and other genetic alterations are also proposed as potential origins of Brugada syndrome, suggesting a polygenic or oligogenic inheritance pattern. However, most of these genetic alterations remain of questionable causality; indeed, rare pathogenic variants in the SCN5A gene are the only established cause of Brugada syndrome. Comprehensive analysis of all reported genetic alterations identified the origin of disease in no more than 40% of diagnosed cases. Therefore, identifying the cause of this rare arrhythmogenic disease in the many families without a genetic diagnosis is a major current challenge in Brugada syndrome. Additional challenges are interpretation/classification of variants and translation of genetic data into clinical practice. Further studies focused on unraveling the pathophysiological mechanisms underlying the disease are needed. Here we provide an update on the genetic basis of Brugada syndrome.