Sex Hormone and Gender Difference?Role of Testosterone on Male Predominance in Brugada Syndrome

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Zusammenfassung. Das Brugada-Syndrom ist ein seltenes, meist familiäres Arrhythmie-Syndrom mit autosomal-dominantem Vererbungsmuster und stellt eine wichtige Differenzialdiagnose von rhythmogenen Synkopen bzw. überlebtem plötzlichen Herztod bei jungen Erwachsenen ohne strukturelle Herzerkrankung dar. Die Diagnostik ist meist erschwert, da die pathognomonischen EKG-Zeichen häufig transient sind und zur definitiven Diagnose oft eine medikamentöse Demaskierung mittels Natriumblocker nötig ist. Die ICD-Implantation ist die einzige effektive Therapie zur Prävention des plötzlichen Herztodes. Für die diesbezügliche Therapieentscheidung ist vor allem bei Zufallsbefunden und asymptomatischen Patienten eine individuelle Risikostratifizierung nötig.

Murine Electrophysiological Models of Cardiac Arrhythmogenesis

Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.

Long-Term Prognosis of Brugada-Type ECG and ECG With Atypical ST-Segment Elevation in the Right Precordial Leads Over 20 Years: Results From the Circulatory Risk in Communities Study (CIRCS)

Background

Brugada syndrome is recognized as being associated with sudden cardiac death; however, the prevalence of non–type 1 Brugada‐type ECG (BrS) or atypical ST‐segment elevation in the right precordial leads (STERP) and the long‐term prognosis for those patients remain unknown.

Methods and Results

We analyzed standard 12‐lead ECGs of 7178 apparently healthy participants (age range 40–64 years) who underwent health checkups from 1982 to 1986 in the Circulatory Risk in Communities Study, a prospective, large, community‐based cohort study in Japan. ECGs with J point amplitude ≥0.2 mV in the right precordial leads were divided into 3 groups: (1) type 1 BrS, (2) type 2 or 3 BrS (non‐type 1 BrS), and (3) STERP. The others served as the non–ST‐segment elevation group. We identified 8 participants (0.1%) with type1 BrS, 84 (1.2%) with non–type 1 BrS, and 228 (3.2%) with STERP. During a median follow‐up of 18.7 years (133 987.0 person‐years), sudden cardiac death was observed in no participants (0.0%) with type 1 BrS, in 1 (1.2%) with non–type 1 BrS, in 7 (3.1%) with STERP, and in 50 (0.7%) with non–ST‐segment elevation. Participants with STERP had a markedly elevated risk of sudden cardiac death (multivariable hazard ratio 3.9, 95% CI 1.7–9.0).

Conclusions

STERP was associated with an elevated risk of sudden cardiac death in a middle‐aged population.

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.

Cardiac conduction defects and Brugada syndrome: A family with overlap syndrome carrying a nonsense SCN5A mutation

Background

Phenotypes often differ even within family members carrying the same SCN5A mutation. We aimed to evaluate the genetic modifiers in a family with Brugada syndrome (BrS) and sick sinus syndrome (SSS) with an SCN5A mutation that causes the truncated alpha-subunit of cardiac Na channel protein.

Methods

To detect the genetic modifiers, we performed targeted panel sequencing of the coding region of 46 genes that are related to primary arrhythmia syndrome, by using a bench-top, next generation sequencer. Phenotype–genotype relationships were evaluated among the family members.

Results

Index proband was a 13-year old (yo) boy with cardiac conduction defect as well as BrS. Genetic analysis revealed that he and his three asymptomatic family members carried a novel nonsense mutation: SCN5A-Q779X. Both genotype-positive mother and sister exhibited coved type ST elevation and his sister had SSS, whereas his elder brother exhibited saddleback type ST elevation induced by pilsicainide administration. We detected four non-synonymous variants (DSG2-R773K, SCN1B-L210P, -S248R, and -R250T) in the proband, his mother and his sister, but not in his brother.

Conclusion

Phenotypic differences between the proband and his brother carrying the same nonsense SCN5A mutation could be explained by modifiers such as SCN1B, and DSG2 gene variants.

p.D1690N sodium voltage-gated channel α subunit 5 mutation reduced sodium current density and is associated with Brugada syndrome

Brugada syndrome (BrS) is an inherited primary arrhythmia disorder, leading to sudden cardiac death due to ventricular tachyarrhythmia, but does not exhibit clinical cardiac abnormalities. The sodium voltage-gated channel α subunit 5 (SCN5A) gene, which encodes the α subunit of the cardiac sodium channel, Nav1.5, is the most common pathogenic gene, although ≥22 BrS‑susceptibility genes have previously been identified. In the present study, a novel genetic variant (p.D1690N) localized in the S5‑S6 linker of domain IV of the Nav1.5 channels was identified in a Chinese Han family. Wild‑type (WT) and p.D1690N Nav1.5 channels were transiently over‑expressed in HEK293 cells and analyzed via the whole-cell patch clamp technique. The p.D1690N mutation significantly reduced the peak sodium current density to 23% of WT (at ‑20 mV; P<0.01), shifted steady‑state activation by 7 mV to increasingly positive potentials (P<0.01). Furthermore, prolonging of the recovery from inactivation was observed in the p.D1690N mutant. No significant change was identified in steady‑state inactivation. Thus, the mutant‑induced changes contributed to the loss of function of Nav1.5 channels, which indicates that the p.D1690N variant may have a pathogenic role in BrS.

Ion Channel Diseases: an Update for 2016

OPINION STATEMENT

Ion channelopathies are a frequent cause of sudden cardiac death (SCD) in patients with structurally normal hearts. These are generally Mendelian inherited electrical disorders with variable penetrance and expressivity. The ability to predict the development of life threatening arrhythmias in these patients is challenging. This chapter will present an update on the genetics, the role of genetic testing, and management of the inherited cardiac channelopathies with a focus on the relatively more common syndromes associated with an increased risk of SCD.

Impact of clinical and genetic findings on the management of young patients with Brugada syndrome

BACKGROUND

Brugada syndrome (BrS) is an arrhythmogenic disease associated with sudden cardiac death (SCD) that seldom manifests or is recognized in childhood.

OBJECTIVES

The objectives of this study were to describe the clinical presentation of pediatric BrS to identify prognostic factors for risk stratification and to propose a data-based approach management.

METHODS

We studied 106 patients younger than 19 years at diagnosis of BrS enrolled from 16 European hospitals.

RESULTS

At diagnosis, BrS was spontaneous (n = 36, 34%) or drug-induced (n = 70, 66%). The mean age was 11.1 ± 5.7 years, and most patients were asymptomatic (family screening, (n = 67, 63%; incidental, n = 13, 12%), while 15 (14%) experienced syncope, 6(6%) aborted SCD or symptomatic ventricular tachycardia, and 5 (5%) other symptoms. During follow-up (median 54 months), 10 (9%) patients had life-threatening arrhythmias (LTA), including 3 (3%) deaths. Six (6%) experienced syncope and 4 (4%) supraventricular tachycardia. Fever triggered 27% of LTA events. An implantable cardioverter-defibrillator was implanted in 22 (21%), with major adverse events in 41%. Of the 11 (10%) patients treated with hydroquinidine, 8 remained asymptomatic. Genetic testing was performed in 75 (71%) patients, and SCN5A rare variants were identified in 58 (55%); 15 of 32 tested probands (47%) were genotype positive. Nine of 10 patients with LTA underwent genetic testing, and all were genotype positive, whereas the 17 SCN5A-negative patients remained asymptomatic. Spontaneous Brugada type 1 electrocardiographic (ECG) pattern (P = .005) and symptoms at diagnosis (P = .001) were predictors of LTA. Time to the first LTA event was shorter in patients with both symptoms at diagnosis and spontaneous Brugada type 1 ECG pattern (P = .006).

CONCLUSION

Spontaneous Brugada type 1 ECG pattern and symptoms at diagnosis are predictors of LTA events in the young affected by BrS. The management of BrS should become age-specific, and prevention of SCD may involve genetic testing and aggressive use of antipyretics and quinidine, with risk-specific consideration for the implantable cardioverter-defibrillator.

Clinical characterisation and long-term prognosis of women with Brugada syndrome

OBJECTIVES

Brugada syndrome (BS) in women is considered an infrequent condition with a more favourable prognosis than in men. Nevertheless, arrhythmic events and sudden cardiac death (SCD) also occur in this population. Long-term follow-up data of this group are sparse. The purpose of the present study was to investigate the clinical characteristics and long-term prognosis of women with BS.

METHODS

A consecutive cohort of 228 women presenting with spontaneous or drug-induced Brugada type I ECG at our institution were included and compared with 314 men with the same diagnosis.

RESULTS

Mean age was 41.5±17.3 years. Clinical presentation was SCD in 6 (2.6%), syncope in 51 (22.4%) and the remaining 171 (75.0%) were asymptomatic. As compared with men, spontaneous type I ECG was less common (7.9% vs 23.2%, p<0.01) and less ventricular arrhythmias were induced during programmed electrical stimulation (5.5% vs 22.3%, p<0.01). An implantable cardioverter defibrillator (ICD) was implanted in 64 women (28.1%). During a mean follow-up of 73.2±56.2 months, seven patients developed arrhythmic events, constituting an event rate of 0.7% per year (as compared with 1.9% per year in men, p=0.02). Presentation as SCD or sinus node dysfunction (SND) was risk factor significantly associated with arrhythmic events (hazard risk (HR) 25.4 and 9.1).

CONCLUSION

BS is common in women, representing 42% of patients in our database. Clinical presentation is less severe than men, with more asymptomatic status and less spontaneous type I ECG and prognosis is more favourable, with an event rate of 0.7% year. However, women with SCD or previous SND are at higher risk of arrhythmic events.

The spectrum of epidemiology underlying sudden cardiac death

Sudden cardiac death (SCD) from cardiac arrest is a major international public health problem accounting for an estimated 15%-20% of all deaths. Although resuscitation rates are generally improving throughout the world, the majority of individuals who experience a sudden cardiac arrest will not survive. SCD most often develops in older adults with acquired structural heart disease, but it also rarely occurs in the young, where it is more commonly because of inherited disorders. Coronary heart disease is known to be the most common pathology underlying SCD, followed by cardiomyopathies, inherited arrhythmia syndromes, and valvular heart disease. During the past 3 decades, declines in SCD rates have not been as steep as for other causes of coronary heart disease deaths, and there is a growing fraction of SCDs not due to coronary heart disease and ventricular arrhythmias, particularly among certain subsets of the population. The growing heterogeneity of the pathologies and mechanisms underlying SCD present major challenges for SCD prevention, which are magnified further by a frequent lack of recognition of the underlying cardiac condition before death. Multifaceted preventative approaches, which address risk factors in seemingly low-risk and known high-risk populations, will be required to decrease the burden of SCD. In this Compendium, we review the wide-ranging spectrum of epidemiology underlying SCD within both the general population and in high-risk subsets with established cardiac disease placing an emphasis on recent global trends, remaining uncertainties, and potential targeted preventive strategies.

Evaluation of the Necessity for Cardioverter-Defibrillator Implantation in Elderly Patients With Brugada Syndrome

Background—

The clinical characteristics and prognosis of elderly patients with Brugada syndrome (BrS) are largely unknown. The purpose of this study was to evaluate the risks and benefits of implantable cardioverter defibrillator (ICD) in elderly patients with BrS based on a long follow-up.

Methods and Results—

A total of 120 BrS patients with ICD (90 for aborted sudden cardiac arrest or syncope, mean age, 46.6±12.2 years; 50 with age ≥60 years at the last follow-up) were included in this study. During 102±68 months of follow-up, 31 patients (26%) experienced appropriate shocks. Age at the first attack of ventricular fibrillation (VF) was <70 years in all patients (mean, 45.0±12.1 years), the incidence of VF decreased with age, and VF did not recur after 70 years of age except in 2 patients with ischemic heart disease. Eleven of 28 patients with supraventricular tachycardia experienced inappropriate shocks. These inappropriate shocks increased with age and reached a peak in patients who were in their sixties. Lead failures occurred in later stages after implantation in 10 of 120 patients (8%).

Conclusions—

Long-term follow-up of high-risk BrS patients with ICD showed a low incidence of VF in those aged >70 years. Considering the increasing risk of inappropriate shocks because of the relatively late onset of supraventricular tachycardia and lead failures, avoidance of ICD implantation, or replacement may be considered in elderly BrS patients who remain free from VF until 70 years of age.

Sex differences in congenital heart defects and genetically induced arrhythmias

Sex medicine can be applied to define the effect of male or female sex-associated differences on the prevalence of congenital heart defects (CHDs), on clinical manifestation of the latter, on means of dealing with the defects and facing consequent surgical treatment, as well as on the success of surgery. The widespread use of modern databases has undoubtedly enhanced the possibility of these observations compared to the past, when findings were limited to case series from single cardiology or paediatric heart surgery units. The aim of the present review is to assess all publications present in the literature on sex differences and CHD, placing particular emphasis on both contradictory aspects and less acknowledged issues. Furthermore, a section of the review is devoted to the effect of sex differences on cardiac arrhythmias, particularly the largely genetically predetermined electrophysiological differences observed between men and women.

Brugada syndrome: clinical and genetic findings

Brugada syndrome is a rare, inherited cardiac disease leading to ventricular fibrillation and sudden cardiac death in structurally normal hearts. Clinical diagnosis requires a Brugada type I electrocardiographic pattern in combination with other clinical features. The most effective approach to unmasking this diagnostic pattern is the use of ajmaline and flecainide tests, and the most effective intervention to reducing the risk of death is the implantation of a cardioverter defibrillator. To date, 18 genes have been associated with the disease, with the voltage-gated sodium channel α type V gene (SCN5A) being the most common one to date. However, only 30-35% of diagnosed cases are attributable to pathogenic variants in known genes, emphasizing the need for further genetic studies. Despite recent advances in clinical diagnoses and genetic testing, risk stratification and clinical management of patients with Brugada syndrome remain challenging.Genet Med 18 1, 3-12.

J wave syndromes: a decade of progress

OBJECTIVE

The objective was to provide a brief history of J wave syndromes and to summarize our current understanding of their molecular, ionic, cellular mechanisms, and clinical features. We will also discuss the existing debates and further direction in basic and clinical research for J wave syndromes.

DATA SOURCES

The publications on key words of "J wave syndromes", "early repolarization syndrome (ERS)", "Brugada syndrome (BrS)" and "ST-segment elevation myocardial infarction (STEMI)" were comprehensively reviewed through search of the PubMed literatures without restriction on the publication date.

STUDY SELECTION

Original articles, reviews and other literatures concerning J wave syndromes, ERS, BrS and STEMI were selected.

RESULTS

J wave syndromes were firstly defined by Yan et al. in a Chinese journal a decade ago, which represent a spectrum of variable phenotypes characterized by appearance of prominent electrocardiographic J wave including ERS, BrS and ventricular fibrillation (VF) associated with hypothermia and acute STEMI. J wave syndromes can be inherited or acquired and are mechanistically linked to amplification of the transient outward current (I to )-mediated J waves that can lead to phase 2 reentry capable of initiating VF.

CONCLUSIONS

J wave syndromes are a group of newly highlighted clinical entities that share similar molecular, ionic and cellular mechanism and marked by amplified J wave on the electrocardiogram and a risk of VF. The clinical challenge ahead is to identify the patients with J wave syndromes who are at risk for sudden cardiac death and determine the alternative therapeutic strategies to reduce mortality.

Bringing home the bacon? The next step in cardiac sodium channelopathies

Mutations in SCN5A, which encodes the α subunit of the major cardiac sodium channel Na(V)1.5, are associated with multiple cardiac arrhythmias, including Brugada syndrome. It is not clear why mutations in SCN5A result in such a variety of cardiac phenotypes, and introduction of analogous Scn5a mutations into small-animal models has not recapitulated alterations in cardiac physiology associated with human disease. In this issue of the JCI, Park and colleagues present a pig model of cardiac sodium channelopathy that was generated by introducing a human Brugada syndrome-associated SCN5A allele. This large-animal model exhibits many phenotypes seen in patients with SCN5A loss-of-function mutations and has the potential to provide important insight into sodium channelopathies.

The usual suspects in sudden cardiac death of the young: a focus on inherited arrhythmogenic diseases

Up to 14,500 young individuals die suddenly every year in Europe of cardiac pathologies. The majority of these tragic events are related to a group of genetic defects that predispose the development of malignant arrhythmias (inherited arrhythmogenic diseases [IADs]). IADs include both cardiomyopathies (hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy) and channelopathies (long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia). Every time an IAD is identified in a patient, other individuals in his/her family may be at risk of cardiac events. However; if a timely diagnosis is made, simple preventative measures may be applied. Genetic studies play a pivotal role in the diagnosis of IADs and may help in the management of patients and their relatives.

Repolarization characteristics in early repolarization and brugada syndromes: insight into an overlapping mechanism of lethal arrhythmias

INTRODUCTION

We reported impaired QT-rate dependence in early repolarization syndrome (ERS); however, contemporary data have shown peak incidence of sudden cardiac death (SCD) in ERS and Brugada syndrome (BrS) at mid-night and early morning. Taken together, we analyzed the nocturnal QT-rate dependence in both syndromes.

METHODS AND RESULTS

A total of 172 subjects were enrolled: 11 ERS, 11 BrS patients, 50 subjects with an uneventful ER pattern (ERP), and 100 non-J-wave control subjects. Ambulatory ECG-derived parameters (QT, QTc, and QT/RR slope) and day-night QT difference were analyzed and compared. Among the groups, there was no significant difference in the average QT or QTc; however, the 24-hour QT/RR slope was significantly smaller in ERS and BrS patients (0.103 ± 0.01 and 0.106 ± 0.01, respectively) than in the control group (0.156 ± 0.03, P < 0.001). Detailed analysis showed a lower day-night QT difference in ERS and BrS patients (19 ±18.7 and 24 ±14 milliseconds, respectively) than in the controls (40 ± 22 milliseconds, P = 0.007) with the lowest QT/RR slopes seen in the ERS and BrS groups from 0 to 3:00 am (QT/RR; 0.076 ± 0.02 vs. 0.092 ± 0.04 vs. 0.117 ± 0.04, for the ERS, BrS, and controls, respectively, P = 0.004) and from 3 to 6 am (QT/RR 0.074 ± 0.03 vs. 0.079 ± 0.02 vs. 0.118 ± 0.04, P < 0.001).

CONCLUSION

In a large population of age- and gender-matched groups, both ERS and BrS patients showed attenuated QT-rate dependence and impaired QT day-night modulation that may provide a baseline reentrant substrate. Importantly, QT/RR maladaptation was most evident at mid-night and early morning, which may explain the propensity of such patients to develop SCD during this critical period.

Cellular and ionic basis of J-wave syndromes

J-wave syndromes are disorders of ventricular repolarization characterized by prominent J waves on the ECG and have the potential to predispose affected individuals to lethal ventricular arrhythmias. These disorders share a common cellular mechanism with prominent Ito in ventricular epicardium. This current causes transmural dispersion of repolarization and the generation of phase 2 reentry, leading to short-coupled extrasystoles and VF. Several autonomic, chemical, and hormonal factors modulate Ito and are therefore vital in attenuating or increasing the arrhythmic potential of these syndromes. Future research should focus on evaluating the arrhythmogenic potential of patients with pathogenic genotypes and/or J waves and no history of VF.

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.>.

The clinical significance of pregnancy in Brugada syndrome

INTRODUCTION AND OBJECTIVES

Little is known about the risks and outcomes of pregnancy in women with Brugada syndrome. We therefore evaluated pregnancy outcomes and the influence of pregnancy in patients with Brugada syndrome.

METHODS

A retrospective analysis was performed in all pregnant women with Brugada syndrome. We included 104 women with a total of 219 deliveries.

RESULTS

There were 15 spontaneous abortions. One infant died suddenly during the night 3 months after birth. Six pregnant women reported they had experienced at least 1 syncope during the pregnancy. Of the 3 women who received an implantable cardioverter-defibrillator before the pregnancy, none received arrhythmia episodes. There were no events during the pregnancy in 4 patients with a previously aborted sudden cardiac death. Of 24 patients with syncope when not pregnant, 18 were asymptomatic and 6 experienced a recurrent syncope during the pregnancy. During the follow-up (mean follow-up 298.9 days; 95% confidence interval, 289.6-308.2), 2 women received appropriate shocks.

CONCLUSIONS

In this retrospective, single-center study, serious events were not more frequent during pregnancy and the peripartum period in women with Brugada syndrome. The occurrence of syncope during pregnancy was not associated with a worst outcome in the peri- and postpartum periods or during follow-up. The reported rate of miscarriage and sudden infant death will require further studies to confirm or rule out its association with Brugada syndrome.

Brugada syndrome: an update

More than 20 years have passed since the description of Brugada syndrome as a clinical entity. The original case series depicted patients who all had coved ST-segment elevation in the right precordial leads, associated with a high risk of sudden death and no apparent structural heart disease. As subsequent registry data were published, it became apparent that the spectrum of risk is wide, with the majority of patients classified as low risk. Two consensus documents have been published that will continue to be updated. Despite intense research efforts, many controversies still exist over its pathophysiology and the risk stratification for sudden death. Management continues to be challenging with a lack of drug therapy and high complication rates from implantable cardioverter defibrillators. In this review, we highlight the current state-of-the-art therapies and their controversies.

Gender modulates the aging effects on different patterns of early repolarization

Distinct patterns of early repolarization (ER) are associated with ventricular fibrillation and arrhythmic death. We evaluated whether gender modulated the aging effects on different ER patterns. We studied manifestations of ER in the anterior, inferior, and lateral leads on standard 12-lead electrocardiography from male (n = 1077) and female (n = 1170) individuals of young (≤44 years), middle-aged (45-64 years), and elderly (≥65 years) subjects. Among a total of 2247 individuals, 543 (24.2 %) subjects had ER and 417 (18.6 %) had single-location ER. Single-location ER occurred less in lateral leads than in anterior or inferior leads (2.1, 7.8, 8.6 %, respectively, p < 0.05). Subjects with inferior ER (n = 193) were older (61 ± 14, 49 ± 14, 54 ± 16 years, respectively, p < 0.05) than those with anterior (n = 176) or lateral (n = 48) ER. In males with ER, the elderly group (n = 22) had fewer instances of anterior ER (34, 59, 80 %, respectively, p < 0.05) than middle-aged (n = 76) or young (n = 59) groups. Elderly males (n = 37) and females (n = 48) had greater instances of inferior ER (57, 32, 19 %, p < 0.05; 86, 62, 46 %, respectively, p < 0.05) than middle-aged males (n = 41) and females (n = 41), and young males (n = 14) and females (n = 12), respectively. In conclusion, gender modulates the aging effects on the occurrences of anterior ER and inferior ER.

Arrhythmogenesis in Brugada syndrome: impact and constrains of current concepts

Brugada syndrome (BrS), an inherited arrhythmogenic disease first described in 1992, is characterized by ST segment elevations on the electrocardiogram in the right precordium and by a high occurrence of arrhythmias including the life-threatening ventricular tachycardia/fibrillation. Knowledge of the underlying mechanisms of formation of arrhythmogenic substrate in BrS is essential, namely for the risk stratification of BrS patients and their therapy which is still restrained almost exclusively to the implantation of cardioverter/defibrillator. In spite of many crucial findings in this field published within recent years, the final consistent view has not been established so far. Hence, BrS described 20 years ago remains an actual topic of both clinical and experimental studies. This review presents an overview of the current knowledge related to the pathogenesis of BrS arrhythmogenic substrate, namely of the genetic basis of BrS, functional consequences of mutations related to BrS, and arrhythmogenic mechanisms in BrS.

Sex and gender aspects in antiarrhythmic therapy

Although cardiac arrhythmia had long been considered a predominantly male syndrome, it is now clear that arrhythmia is also a primary cause of mortality in women. Notably, the manifestation of specific arrhythmia syndromes appears to be gender specific. In particular, female sex is an independent risk factor for development of torsade de pointes (TdP) arrhythmias not only in congenital long QT syndromes but also in acquired long QT syndromes which occur as adverse effects of existing drugs. Males, on the other hand, are more likely to develop Brugada syndrome. Recent clinical and experimental studies suggest that these differences may stem from intrinsic sex differences in cardiac tissue. These include fundamental electrical differences resulting from variable ion channel expression and diverse sex hormonal regulation via long-term genomic and acute nongenomic pathways, and sex differences in drug responses and metabolisms. Undoubtedly, determining the effect of gender on cardiac function will be difficult and require sophisticated methodologies. However, gender differences underlying predilection to distinct arrhythmia syndromes must be revealed so that new therapeutic strategies that take gender into account can be applied to at-risk patients.

Lack of Influence of the Androgen Receptor Gene CAG-Repeat Polymorphism on Clinical and Electrocardiographic Manifestations of the Brugada Syndrome in Man

Background

Clinical studies suggest that testosterone (T) plays an important role in the male predominance of the clinical manifestations of the Brugada syndrome (BS). However, no statistically significant correlations have been observed between T levels and electrocardiogram (ECG) parameters in the BS patients. We investigated whether the hormonal pattern and the variation within CAG repeat polymorphism in exon 1 of the androgen receptor (AR) gene, affecting androgen sensitivity, are associated with the Brugada ECG phenotype in males.

Methods and Results

16 male patients with BS (mean age 45.06 ± 11.3 years) were studied. 12-lead ECG was recorded. Blood levels of follicle-stimulating hormone, luteinizing hormone, prolactin, testosterone, free-T, dihydrotestosterone, 17-β-estradiol, estrone, 3-alpha-androstanediol-glucuronide, delta-4-androstenedione, dehydroepiandrosterone sulphate, progesterone, 17-hydroxyprogesterone, and sex hormone binding globulin were assayed. Genotyping of CAG repeats on DNA extracted from leukocytes was carried out. No relationship was found between hormone values and ECG parameters of BS. BS patients showed the CAG length normally recognized in the human polymorphism range and the number of CAG repeats did not correlate with the ECG pattern of BS.

Conclusions

The AR CAG repeat length does not correlate with the ECG features of the patients affected by BS. The search for genes downstream AR activation as possibly responsible for the increased risk of spontaneous arrhythmias in BS males after puberty is warranted.

Genetic, molecular and cellular mechanisms underlying the J wave syndromes

An early repolarization (ER) pattern in the ECG, distinguished by J-point elevation, slurring of the terminal part of the QRS and ST-segment elevation has long been recognized and considered to be a benign electrocardiographic manifestation. Experimental studies conducted over a decade ago suggested that some cases of ER may be associated with malignant arrhythmias. Validation of this hypothesis was provided by recent studies demonstrating that an ER pattern in the inferior or inferolateral leads is associated with increased risk for life-threatening arrhythmias, termed ER syndrome (ERS). Because accentuated J waves characterize both Brugada syndrome (BS) and ERS, these syndromes have been grouped under the term "J wave syndromes". ERS and BS share similar ECG characteristics, clinical outcomes and risk factors, as well as a common arrhythmic platform related to amplification of I(to)-mediated J waves. Although BS and ERS differ with respect to the magnitude and lead location of abnormal J wave manifestation, they can be considered to represent a continuous spectrum of phenotypic expression. Although most subjects exhibiting an ER pattern are at minimal to no risk, mounting evidence suggests that careful attention should be paid to subjects with "high risk" ER. The challenge ahead is to be able to identify those at risk for sudden cardiac death. Here I review the clinical and genetic aspects as well as the cellular and molecular mechanisms underlying the J wave syndromes.

Genetic and clinical aspects of Brugada syndrome: an update

The Brugada Syndrome (BS) is a "channellopathy," characterized by ion (e.g., sodium, calcium, and potassium) channel dysfunction and typical ECG alterations, originally described by Osher and Wolff in 1953 and further elucidated by Josep and Pedro Brugada in 1991. BS is typically associated with a high risk for sudden cardiac death (SCD) in young and otherwise healthy adults. Although in several patients the heart is structurally normal, subtle structural abnormalities in the right ventricular outflow tract are increasingly been reported. The worldwide prevalence of this disorder is still uncertain, and there are some significant regional differences. The syndrome is characterized by a strong genetic basis, and several mutations have been identified in genes encoding subunits of cardiac sodium, potassium, and calcium channels, as well as in genes involved in the trafficking or regulation of these channels. Accordingly, eight types of BS (from BS1 to BS8) have already been described, involving mutations in SCN5A, GPD1-L, CACNA1c, CACNB2b, SCN1B, KCNE3, SCN3B, and HCN4 genes. The vast majority (i.e., up to two-third) of BS patients is asymptomatic, whereas the leading clinical manifestation is polymorphic ventricular tachycardia that can degenerate into ventricular fibrillation (VF) and SCD. The diagnosis is still challenging, and ECG abnormalities represent one component of the diagnostic criteria which also include clinical and demographic data. Although molecular genetic testing is effective in detecting mutations in 20-38% of BS patients, it represents an appealing option for stratifying the risk of adverse events as well as for prenatal testing.

Electrical storm in Brugada syndrome during pregnancy

Clinical and molecular characterization of the Brugada syndrome has progressed rapidly since its initial description. The role of hormonal changes during pregnancy and postpartum period on the pathogenesis of Brugada syndrome has not been studied. Herein, we describe a case of revelation of Brugada syndrome during pregnancy in a young woman who presented with electrical storm as the first manifestation. Low-dose isoproterenol infusion followed by oral quinidine inhibited the recurrence of ventricular tachyarrhythmia and normalized the electrocardiographic pattern. We emphasize the importance of hormonal changes during pregnancy as a precipitating factor for arrhythmic events in Brugada syndrome.

Incidence and prognostic value of early repolarization pattern in the 12-lead electrocardiogram

BACKGROUND

Early repolarization pattern is a common ECG finding characterized by J-point elevation and QRS notching or slurring in the inferior and/or lateral leads, yet little is known about its incidence and long-term prognosis in Asian populations.

METHODS AND RESULTS

We reviewed all the ECG records of the 5976 atomic-bomb survivors who were examined at least once during our biennial health examination in Nagasaki, Japan, between July 1958 and December 2004. We defined early repolarization pattern as ≥0.1-mV elevation of the J point or ST segment, with notching or slurring in at least 2 inferior and/or lateral leads. We assessed unexpected, cardiac, and all-cause death risk by Cox analysis. We identified 1429 early repolarization pattern cases (779 incident cases) during follow-up, yielding a positive rate of 23.9% and an incidence rate of 715 per 100 000 person-years. Early repolarization pattern had an elevated risk of unexpected death (hazard ratio, 1.83; 95% confidence interval, 1.12 to 2.97; P=0.02) and a decreased risk of cardiac (hazard ratio, 0.75; 95% confidence interval, 0.60 to 0.93; P<0.01) and all-cause (hazard ratio, 0.85; 95% confidence interval, 0.78 to 0.93; P<0.01) death. In addition, both slurring and notching were related to higher risk of unexpected death (hazard ratio, 2.09; 95% confidence interval, 1.06 to 4.12; P=0.03), as was early repolarization pattern manifestation in both inferior and lateral leads (hazard ratio, 2.50; 95% confidence interval, 1.29 to 4.83; P<0.01).

CONCLUSIONS

Early repolarization pattern is associated with an elevated risk of unexpected death and a decreased risk of cardiac and all-cause death. Specific early repolarization pattern morphologies and location are associated with an adverse prognosis.

Aborted sudden cardiac death in adolescent

Sudden cardiac death is rare in children and adolescents but accounts for 19% to 30% of sudden deaths until 21 years of age. Fatal ventricular arrhythmias are usual common pathways in such tragic events, and underlying etiologies include cardiac ion channelopathies in majority of cases. We present a case of aborted sudden cardiac death in field, resuscitated successfully, and a clinical event in the pediatric emergency department that led to the diagnosis of the underlying rare condition.

Arrhythmia and right heart disease: from genetic basis to clinical practice

Historically, left ventricular cardiomyopathy and coronary heart disease have been regarded as the main causes of ventricular arrhythmia and sudden cardiac death. However, within last two decades, arrhythmias originating from the right ventricle have begun to attract the attention of the scientific world for a number of reasons. Ventricular arrhythmias originating from the right ventricle usually affect younger patients and can lead to sudden cardiac death. The pathophysiologic mechanism of these arrhythmias is not fully understood, which can leave room for a range of different interpretations. Moreover, the intriguing world of genetics is increasingly being drawn into the pathogenesis, diagnosis and prognosis of some of these arrhythmias. This review considers the pathogenesis, diagnosis and treatment of arrhythmogenic right ventricular cardiomyopathy or dysplasia (ARVD), Brugada syndrome, right ventricular outflow tract ventricular tachycardia, and arrhythmias in the right side of the heart due to congenital heart disease. In addition, because ventricular arrhythmias associated with right ventricular heart diseases such as Brugada syndrome and ARVD can explain up to 10-30% of sudden cardiac deaths in young adults in the general population and an even greater percentage in young athletes, this article contains a brief analysis of screening tests used before participation in sports, life-style modification, and treatment options for athletes affected by these conduction disorders.

Brugada Syndrome 2010

The Brugada syndrome is a genetically determined cardiac disorder, presenting with characteristic electrocardiogram features and high risk of sudden cardiac death from polymorphic ventricular tachycardia/ventricular fibrillation in young individuals with a structurally normal heart. Scientific knowledge about the disease has grown exponentially in recent years. Two consensus reports on the disease were published (in 2002 and 2005) in an effort to state diagnostic criteria, risk stratification, and treatment indications. However, substantial controversies remain, especially considering risk stratification of asymptomatic patients. Given the enormous amount of valuable information collected by many groups since the consensus reports, current diagnostic criteria, recommended prognostic tools, and treatment must be reviewed. This article briefly reviews recent advances in understanding of Brugada syndrome and its genetic and molecular basis, arrhythmogenic mechanisms, and clinical course. An update of tools for risk stratification and treatment of the condition is also included.

Differences in sino-atrial and atrio-ventricular function with age and sex attributable to the Scn5a+/- mutation in a murine cardiac model

AIM

To investigate the interacting effects of age and sex on electrocardiographic (ECG) features of Scn5a(+/-) mice modelling Brugada syndrome.

METHODS

Recordings were performed on anaesthetized wild-type (WT) and Scn5a(+/-) mice and differences attributable to these risk factors statistically stratified.

RESULTS

Scn5a(+/-) exerted sex-dependent effects upon sino-atrial function that only became apparent with age. RR intervals were greater in old male than in old female Scn5a(+/-). Atrio-ventricular (AV) conduction was slower in young female mice, whether WT and Scn5a(+/-), than the corresponding young male WT and Scn5a(+/-). However, PR intervals lengthened with age in male but not in female Scn5a(+/-) giving the greatest PR intervals in old male Scn5a(+/-) compared with either old male WT or young male Scn5a(+/-) mice. In contrast, PR intervals were similar in old female Scn5a(+/-) and in old female WT. QTc was prolonged in Scn5a(+/-) compared with WT, and female Scn5a(+/-) compared with female WT. Age-dependent alterations in durations of ventricular repolarization relative to WT affected male but not female Scn5a(+/-). Thus, T-wave durations were greater in old male Scn5a(+/-) compared with old male WT, but indistinguishable between old female Scn5a(+/-) and old female WT. Finally, analysis for combined interactions of genotype, age and sex demonstrated no effects on P wave and QRS durations and QTc intervals.

CONCLUSION

We demonstrate for the first time that age, sex and genotype exert both independent and interacting ECG effects. The latter suggest alterations in cardiac pacemaker function, atrio-ventricular conduction and ventricular repolarization greatest in ageing male Scn5a(+/-).