Fever-induced life-threatening arrhythmias in children harboring an SCN5A mutation

Recent Advances in Inherited Cardiac Arrhythmias and Their Genetic Testing

Inherited arrhythmias, encompassing conditions such as cardiomyopathies, cardiac ion channel disorders, and coronary heart disease, represent the common causes that elevate the threat of sudden cardiac death among adults. Researchers have pinpointed the genes responsible for these hereditary arrhythmias in the last 30 years. Concurrently, it has become clear that the genetic makeup underlying these conditions is more intricate than previously understood. Evolution in DNA sequencing techniques, particularly next-generation sequencing, has empowered us to learn these intricate hereditary characteristics. Genetic testing is crucial in diagnosing, assessing risk, and determining treatment for individuals with these conditions and their family members. The need for collaborative endeavors to comprehend and address these uncommon yet potentially life-threatening disorders is becoming more evident. This review aims to inform readers of the latest advances in understanding hereditary arrhythmias and provide the groundwork for collaborative genetic testing initiatives to characterize these disorders in the general population.

Brugada syndrome - minimizing overdiagnosis and over treatment in children

PURPOSE OF REVIEW

Is to summarise the new contributions toward the understanding of the broad spectrum of manifestations of Brugada syndrome (BrS) during the first years of life. The review encompasses the screening of the asymptomatic patient referred due to family history in one extreme of the spectrum, and also the rare child with early clinical expression of the disease on the opposite side.

RECENT FINDINGS

Involve specific features of pediatric BrS including the risk related to a positive family history of sudden cardiac death, the risk of presenting with syncope and the multiple diagnostic challenges of the disease. We included some of the most controversial aspects of the diagnosis and risk stratification, encompassing noninvasive studies (Holter monitors, exercise test, implantable loop recorders, and provocative tests), as well as invasive stratification during the first years of life. Finally, the role and concerns of genetic testing in this age group are commented upon.

SUMMARY

The main key to minimize overdiagnosis and overtreatment in the young population with a personal and/or family diagnosis of BrS is to perform a systematic but also individualized assessment. Appropriate diagnostic guidelines need to be created and age-specific risk stratification algorithms built for the young patient both with suspected and confirmed BrS.

Clinical Spectrum of SCN5A Channelopathy in Children with Primary Electrical Disease and Structurally Normal Hearts

Sodium voltage-gated channel α subunit 5 (SCN5A)-mutations may cause an array of arrhythmogenic syndromes most frequently as an autosomal dominant trait, with incomplete penetrance, variable expressivity and male predominance. In the present study, we retrospectively describe a group of Mexican patients with SCN5A-disease causing variants in whom the onset of symptoms occurred in the pediatric age range. The study included 17 patients with clinical diagnosis of primary electrical disease, at least one SCN5A pathogenic or likely pathogenic mutation and age of onset <18 years, and all available first- and second-degree relatives. Fifteen patients (88.2%) were male, and sixteen independent variants were found (twelve missense, three truncating and one complex inframe deletion/insertion). The frequency of compound heterozygosity was remarkably high (3/17, 17.6%), with early childhood onset and severe disease. Overall, 70.6% of pediatric patients presented with overlap syndrome, 11.8% with isolated sick sinus syndrome, 11.8% with isolated Brugada syndrome (BrS) and 5.9% with isolated type 3 long QT syndrome (LQTS). A total of 24/45 SCN5A mutation carriers were affected (overall penetrance 53.3%), and penetrance was higher in males (63.3%, 19 affected/30 mutation carriers) than in females (33.3%, 5 affected/15 carriers). In conclusion, pediatric patients with SCNA-disease causing variants presented mainly as overlap syndrome, with predominant loss-of-function phenotypes of sick sinus syndrome (SSS), progressive cardiac conduction disease (PCCD) and ventricular arrhythmias.

Recommendations for participation in leisure-time physical activity and competitive sports of patients with arrhythmias and potentially arrhythmogenic conditions. Part 2: ventricular arrhythmias, channelopathies, and implantable defibrillators

This paper belongs to a series of recommendation documents for participation in leisure-time physical activity and competitive sports by the European Association of Preventive Cardiology (EAPC). Together with an accompanying paper on supraventricular arrhythmias, this second text deals specifically with those participants in whom some form of ventricular rhythm disorder is documented, who are diagnosed with an inherited arrhythmogenic condition, and/or who have an implanted pacemaker or cardioverter defibrillator. A companion text on recommendations in athletes with supraventricular arrhythmias is published in the European Journal of Preventive Cardiology. Since both texts focus on arrhythmias, they are the result of a collaboration between EAPC and the European Heart Rhythm Association (EHRA). The documents provide a framework for evaluating eligibility to perform sports, based on three elements, i.e. the prognostic risk of the arrhythmias when performing sports, the symptomatic impact of arrhythmias while performing sports, and the potential progression of underlying structural problems as the result of sports.

Brugada syndrome clinical update

Brugada syndrome (BrS) was initially described in southeast Asians with a structurally normal heart presenting with polymorphic ventricular tachycardia and fibrillation. This condition is marked by J-point elevation ≥ 2 mm with coved-type ST segment elevation followed by negative T wave inversions in at least one precordial lead (V1 or V2) when other etiologies have been excluded. These changes on electrocardiogram (EKG) can either be spontaneous or manifest after sodium channel blockade. The worldwide prevalence of BrS is about 0.4%; however, it is higher in the Asian population at 0.9%. This article will review the current hypotheses regarding the pathophysiology, spectrum of clinical presentation, strategies for prevention of sudden cardiac death and the treatment for recurrent arrhythmias in BrS.

Electrocardiogram Characteristics and Arrhythmic Events during Fever in Patients with Fever-Induced Brugada Syndrome

Introduction: Changes in electrocardiogram (ECG) parameters and the incidence of arrhythmic events in patients with fever-induced Brugada syndrome (BrS) remain unknown. Objective: We aimed to investigate the effect of hyperthermia on the ECG pattern and the occurrence of fever-triggered arrhythmic events (FTAEs) in patients with fever-induced BrS. Methods: We retrospectively analyzed a series of fever-induced BrS cases from January 1966 to November 2018. Clinical characteristics and ECG parameters were evaluated in the presence or absence of fever. Results: Syncope and implantable cardioverter defibrillator implantation occurred more frequently in BrS patients with FTAEs than in patients without FTAEs. In BrS patients <16 years old, more arrhythmia events occurred in patients with FTAEs than in patients without FTAEs (p = 0.04). During follow-up, 2 patients in the FTAEs group suffered new malignant arrhythmic events. Compared to the afebrile state, the J point increased significantly in precordial leads V1, V2, and V3 during the febrile state (all p < 0.01). The corrected QTpeak intervals in V1 and V2 were significantly longer in the FTAEs group than in the non-FTAEs group (354.5 ± 37.0 vs. 334.3 ± 45.5 ms, p < 0.01 and 368.0 ± 43.4 vs. 330.9 ± 41.5 ms, p < 0.01, respectively). An increased corrected QT dispersion and a lengthened corrected Tpeak-Tend dispersion were also observed during fever. Conclusions: Fever may not only reveal BrS but also induce life-threatening arrhythmic events, especially in children and adolescents.

Arrhythmic events in Brugada syndrome patients induced by fever

INTRODUCTION

The Brugada syndrome is associated with arrhythmic events, which may even lead to sudden cardiac death (SCD) as it causes arrhythmic events. A typical Brugada syndrome ECG type I can be triggered at fever situations. The aim of this pooled meta-analysis is to further explore the baseline characteristics and the association of fever to BrS-related arrhythmic events.

METHODS

We compiled data from a search of databases (PubMed, Web of Science, Cochrane Library, and Google Scholar). We included 17 studies including 14 case reports and a total of 53 patients.

RESULTS

Our population including 53 patients showed a male predominance of 92% with a mean age of 40.6 ± 17.7 years. 58% of patients had a family history of SCD or BrS. Genetic screening was performed in 14 patients (26%) and revealed a SCN5A mutation in 21% of the patients. ICD implantation was initiated in six patients. 75% (n = 39) of patients did not have symptoms before the fever event. Symptoms at fever included life-threatening arrhythmia such as ventricular fibrillation (VF) or ventricular tachycardia (VT; 17%), syncope (13%), and cardiac arrest or aborted SCD (13%). One patient developed electrical storm which led to not aborted SCD.

CONCLUSION

Fever is a great risk factor for arrhythmia events in BrS patients. Patients with known fever triggered Brugada syndrome should be surveilled closely during fever and be started on antipyretic therapy as soon as possible.

Brugada syndrome in the young: an assessment of risk factors predicting future events

Aims

To investigate the clinical characteristics, prognoses, and presence of risk factors in young patients with Brugada syndrome (BS).

Methods and results

A consecutive cohort of 128 young BS patients (≤25 years old at diagnosis) was analysed. Eighty-eight patients (69%) were asymptomatic, whereas 40 (31%) presented with clinical manifestations of BS. Markers of prognosis and risk were identified upon comparison of these two groups. A history of malignant syncope was strong predictors of ventricular arrhythmic events. Family history of sudden cardiac death (SCD) and mutations in the SCN5A gene did not associate with increased risk. Symptomatic patients presented with significantly abnormal baseline electrical characteristics when compared with the asymptomatic cohort, including spontaneous type I electrocardiograph (ECG) patterns, sinus node dysfunction (SND), first-degree atrioventricular (AV) block, and intra-ventricular conduction delay. The symptomatic group more frequently exhibited atrial arrhythmias. Electrophysiological studies resulted positive more frequently in symptomatic patients, but no risk association for future events could be determined. During the follow-up period (mean: 65 months), 10 arrhythmic events occurred in nine symptomatic patients (event rate: 4.5% per year). No events occurred in the asymptomatic group. Variables significantly associated with arrhythmic events during follow-up were presence of symptoms at diagnosis and spontaneous type I ECG. The presence of atrial arrhythmias and conduction abnormalities was also associated with the risk of arrhythmic events during follow-up.

Conclusion

Symptomatic BS in the young age is a rare but malignant condition that can manifest with a spectrum of electrical abnormalities (i.e. SND, atrial tachycardias, AV block, and infra-nodal conduction delay) and result in the extreme cases in lethal arrhythmic events and SCD.

Brugada syndrome in a 4-year-old child with Lemierre syndrome—A case report

Brugada syndrome is a rare arrhythmogenic disease with characteristic electrocardiogram (ECG) findings. Fever represents an important triggering factor. We report the case of a 4-year-old Saudi boy who was diagnosed with Lemierre syndrome and subsequently developed Brugada syndrome.

Beat-to-beat variability of cardiac action potential duration: underlying mechanism and clinical implications

Beat-to-beat variability of cardiac action potential duration (short-term variability, SV) is a common feature of various cardiac preparations, including the human heart. Although it is believed to be one of the best arrhythmia predictors, the underlying mechanisms are not fully understood at present. The magnitude of SV is basically determined by the intensity of cell-to-cell coupling in multicellular preparations and by the duration of the action potential (APD). To compensate for the APD-dependent nature of SV, the concept of relative SV (RSV) has been introduced by normalizing the changes of SV to the concomitant changes in APD. RSV is reduced by I_Ca, I_Kr, and I_Ks while increased by I_Na, suggesting that ion currents involved in the negative feedback regulation of APD tend to keep RSV at a low level. RSV is also influenced by intracellular calcium concentration and tissue redox potential. The clinical implications of APD variability is discussed in detail.

Brugada syndrome: diagnosis, risk stratification, and management

PURPOSE OF REVIEW

Asymptomatic patients with Brugada syndrome (BrS) have a small, but not trivial, risk of cardiac events. Their risk stratification and its impact on their management are controversial. The review focuses on the clinical aspects of BrS with special emphasis on the asymptomatic patient.

RECENT FINDINGS

Emerging data suggest that drug and fever-induced type I Brugada patterns are more common than previously appreciated. Although preliminary, these data may imply that asymptomatic patients with induced Brugada pattern are at an even lower risk than currently estimated.The latest data regarding induced ventricular arrhythmias during electrophysiological studies support its use as an indication for an implantable cardioverter defibrillator; however, this issue remains highly controversial.Several new risk markers, such as presence of the Brugada pattern in infero-lateral leads or the concomitant finding of an early repolarization pattern, have recently been proposed.

SUMMARY

Most asymptomatic BrS patients are at low risk of cardiac events. The presence of new risk markers in this population may prompt consideration of primary prevention measures; however, data supporting this approach are still limited.

Brugada syndrome in the paediatric population: a comprehensive approach to clinical manifestations, diagnosis, and management

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.

Inherited arrhythmias: The cardiac channelopathies

Ion channels in the myocardial cellular membrane are responsible for allowing the cardiac action potential. Genetic abnormalities in these channels can predispose to life-threatening arrhythmias. We discuss the basic science of the cardiac action potential; outline the different clinical entities, including information regarding overlapping diagnoses, touching upon relevant genetics, new innovations in screening, diagnosis, risk stratification, and management. The special considerations of sudden unexplained death and sudden infant death syndrome are discussed. Scientists and clinicians continue to reconcile the rapidly growing body of knowledge regarding the molecular mechanisms and genetics while continuing to improve our understanding of the various clinical entities and their diagnosis and management in clinical setting. Two separate searches were run on the National Center for Biotechnology Information's website. The first using the term cardiac channelopathies was run on the PubMed database using filters for time (published in past 5 years) and age (birth-18 years), yielding 47 results. The second search using the medical subject headings (MeSH) database with the search terms “Long QT Syndrome” (MeSH) and “Short QT Syndrome” (MeSH) and “Brugada Syndrome” (MeSH) and “Catecholaminergic Polymorphic Ventricular Tachycardia” (MeSH), applying the same filters yielded 467 results. The abstracts of these articles were studied, and the articles were categorized and organized. Articles of relevance were read in full. As and where applicable, relevant references and citations from the primary articles where further explored and read in full.

Sudden infant death syndrome, sleep, and seizures

benign febrile seizures seen in 7% of infants before 6 months play a role in the terminal pathway in a subset of sudden infant death syndrome victims. Supporting evidence: (1) lack of 5-hydroxitryptamine, one consistent finding in sudden infant death syndrome that Kinney et al coined a developmental serotonopathy, is consistent with risk for seizures. (2) Non-rapid eye movement sleep increasing during the age of highest risk for sudden infant death syndrome facilitates some seizures (seizure gate). (3) Sudden unexpected death in epilepsy is associated with severe hypoxemia and hypercapnia during postictal generalized electroencephalographic (EEG) suppression. In toddlers, sudden unexplained deaths are associated with hippocampal abnormalities and some seizures. (4) The sudden nature of both deaths warrants an exploration of similarities in the terminal pathway. Moreover, sudden infant death syndrome, febrile seizures, sudden unexplained death in childhood, and sudden unexpected death in epilepsy share some of the following risk factors: prone sleeping, infections, hyperthermia, preterm birth, male gender, maternal smoking, and mutations in genes that regulate sodium channels. State-of-the-art molecular studies can be exploited to test this hypothesis.

Intermittent Brugada syndrome in an anorexic adolescent girl

We report an anorexic adolescent girl with an intermittent Brugada syndrome. A 14-year-old anorexic girl with a body mass index (BMI) of 13.15 kg/m² was admitted in the acute state of the disease with an ST elevation in V1 and V2, suggestive of Brugada syndrome. After 1 month of re-feeding, a control electrograph (ECG) was normal, but after an 8-month follow-up control with a nearly normal BMI, the ECG was again suggestive of Brugada syndrome. A genetic analysis of the gene SNC5A established a genetic change (p Leu 1582 pro), which provides the final explanation for the Brugada syndrome. Every rhythm problem in the acute state or during the re-feeding procedure deserves a strict follow-up to distinguish iatrogenic from heritable rhythm problems. <Learning objective: (i) We report the first case of a patient with anorexia nervosa with an intermittent Brugada syndrome. (ii) Moderate hypothermia can decrease the depolarization of pacemaker cells and cause ST-segment changes. (iii) Every rhythm problem in the acute state or during the re-feeding procedure deserves a strict follow-up to distinguish iatrogenic from heritable rhythm problems. (iv) A genetic analysis can make the distinction and is necessary to give advice for the future lifestyle of the patient.>.

Inherited arrhythmia syndromes leading to sudden cardiac death in the young: a global update and an Indian perspective

Inherited primary arrhythmias, namely congenital long QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia, account for a significant proportion of sudden cardiac deaths in young and apparently healthy individuals. Genetic testing plays an integral role in the diagnosis, risk-stratification and treatment of probands and family members. It is increasingly obvious that collaborative efforts are required to understand and manage these relatively rare but potentially lethal diseases. This article aims to update readers on the recent developments in our knowledge of inherited arrhythmias and to lay the foundation for a national synergistic effort to characterize them in the Indian population.

Cardiac sodium channelopathy associated with SCN5A mutations: electrophysiological, molecular and genetic aspects

Over the last two decades, an increasing number of SCN5A mutations have been described in patients with long QT syndrome type 3 (LQT3), Brugada syndrome, (progressive) conduction disease, sick sinus syndrome, atrial standstill, atrial fibrillation, dilated cardiomyopathy, and sudden infant death syndrome (SIDS). Combined genetic, electrophysiological and molecular studies have provided insight into the dysfunction and dysregulation of the cardiac sodium channel in the setting of SCN5A mutations identified in patients with these inherited arrhythmia syndromes. However, risk stratification and patient management is hindered by the reduced penetrance and variable disease expressivity in sodium channelopathies. Furthermore, various SCN5A-related arrhythmia syndromes are known to display mixed phenotypes known as cardiac sodium channel overlap syndromes. Determinants of variable disease expressivity, including genetic background and environmental factors, are suspected but still largely unknown. Moreover, it has become increasingly clear that sodium channel function and regulation is more complicated than previously assumed, and the sodium channel may play additional, as of yet unrecognized, roles in cardiac structure and function. Development of cardiac structural abnormalities secondary to SCN5A mutations has been reported, but the clinical relevance and underlying mechanisms are unclear. Increased insight into these issues would enable a major next step in research related to cardiac sodium channel disease, ultimately enabling improved diagnosis, risk stratification and treatment strategies.

Ageing and Brugada syndrome: considerations and recommendations

Brugada syndrome is an inherited disease associated with an increased risk of lethal ventricular arrhythmias. Such arrhythmias stem from innate disruptions in cardiac electrophysiology. Typically, such arrhythmias occur in the third or fourth decade of life. However, Brugada syndrome may also affect geriatric patients. In this paper, we focus on the ageing patient with Brugada syndrome, and specifically, on the interaction between Brugada syndrome and the more usually acquired clinical problems that may occur with increasing age, such as the use of cardiovascular and non-cardiovascular drugs, or the need for surgery. Such common conditions may also disrupt cardiac electrophysiology, thereby conferring added risk for Brugada syndrome patients. We present some considerations and recommendations that may serve as guidance to address these complexities.

Cardiac ion channelopathies and the sudden infant death syndrome

The sudden infant death syndrome (SIDS) causes the sudden death of an apparently healthy infant, which remains unexplained despite a thorough investigation, including the performance of a complete autopsy. The triple risk model for the pathogenesis of SIDS points to the coincidence of a vulnerable infant, a critical developmental period, and an exogenous stressor. Primary electrical diseases of the heart, which may cause lethal arrhythmias as a result of dysfunctioning cardiac ion channels (“cardiac ion channelopathies”) and are not detectable during a standard postmortem examination, may create the vulnerable infant and thus contribute to SIDS. Evidence comes from clinical correlations between the long QT syndrome and SIDS as well as genetic analyses in cohorts of SIDS victims (“molecular autopsy”), which have revealed a large number of mutations in ion channel-related genes linked to inheritable arrhythmogenic syndromes, in particular the long QT syndrome, the short QT syndrome, the Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia. Combining data from population-based cohort studies, it can be concluded that at least one out of five SIDS victims carries a mutation in a cardiac ion channel-related gene and that the majority of these mutations are of a known malignant phenotype.

Brugada-like syndrome in infancy presenting with rapid ventricular tachycardia and intraventricular conduction delay

BACKGROUND

Brugada syndrome is a potentially serious channelopathy that usually presents in adulthood and has only rarely been described in infancy. In the absence of metabolic or structural cardiac disease, rapid ventricular tachycardia (>200 bpm) and primary cardiac conduction disease are uncommon in infancy. We hypothesized that infants having rapid ventricular tachycardia and conduction abnormalities and not having structural or metabolic pathogeneses were likely to have mutations in depolarizing current channels.

METHODS AND RESULTS

A retrospective review of all clinical materials from a single institution over a 9-year period from all infants <2 years old and having a discharge diagnosis of ventricular tachycardia or ventricular fibrillation was performed. Among 32 infants fulfilling inclusion criteria, 12 had a structurally normal heart, and 9 of them had either prolonged QRS duration or Brugada pattern while in sinus rhythm. Of those 5 infants not having a definitive pathogenesis, electrophysiological testing had been performed in 4, and genetic testing had been performed in all 5 of those infants. During electrophysiological testing, a prolonged HV interval was present in 2 of 4, inducible ventricular tachycardia was present in 1 of 4, and a type 1 Brugada pattern was induced by intravenous procainamide in 3 of 4. Genetic testing revealed disease-causing mutations in depolarizing sodium (SCN5A) or calcium (CaCNB2b) channels in all 5 infants.

CONCLUSIONS

Infants having rapid ventricular tachycardia and conduction abnormalities in the absence of structural or metabolic abnormalities are likely to have disease-causing mutations in cardiac depolarizing channels.