Sudden Death in the Young

Sudden cardiac death among workers: a systematic review and meta-analysis

OBJECTIVE

Sudden cardiac death (SCD) is a rare and yet unexplained condition. The most frequent cause is myocardial infarction, while a small proportion is due to arrhythmogenic syndromes (e.g., channelopathies). This systematic review and meta-analysis aimed to provide a comprehensive overview of the prevalence and risk factors associated with SCD in workers.

MATERIAL AND METHODS

A search for eligible studies was performed utilizing three databases (PubMed, ISI Web of Knowledge, and Scopus). The inclusion criteria were fulfilled if sudden cardiac death due to channelopathy in workers was mentioned.

RESULTS

Out of the 1408 articles found across three databases, 6 articles were included in the systematic review but the meta-analysis was conducted on 3 studies The total sample included was 23,450 participants. The pooled prevalence of channelopathies in employees was 0.3% (95% CI 0.07-0.43%), of sudden cardiac death in employees was 2.8% (95% CI 0.37-5.20%), and of sudden cardiac death in employees with a diagnosis of cardiac channelopathies was 0.2% (95% CI 0.02- 0.30%).

CONCLUSIONS

SCD is a serious and potentially preventable condition that can occur among workers. By identifying and addressing work-related risk factors, providing appropriate screening and interventions, and promoting healthy lifestyle behaviors, we can work to reduce the incidence of SCD and improve the cardiovascular health and well-being of workers.

A New Inherited Syndrome Causing Sudden Cardiac Death with Distinct ST-Segment Depression and Ankyrin-2-Mutation

Introduction

Sudden cardiac death (SCD) is a serious threat. In individuals under the age of 35 years sudden arrhythmic death is the most frequent cause. In younger persons, genetically determined cardiac diseases (eg, cardiomyopathies and ion-channel diseases) account for an important proportion of these cases.

Methods

We investigated the case of a 23-year-old male with SCD, specific ECG changes and left ventricular hypertrophy. Family history was significant for SCD in the paternal line. A precise analysis was performed by an international multidisciplinary expert panel including autopsy of the index patient's heart, molecular autopsy, whole-exome sequencing, analysis of the pedigree and examination of available family members.

Results

Three cases of SCD were reported in paternal relatives. The index patient exhibited specific ECG changes (ST-depression), which were also found in five paternal relatives and the brother of the index patient. Post-mortem analysis of the heart yielded mild idiopathic concentric hypertrophy without myocardial disarray. The genetic analysis of the index patient showed two nucleotide variations in two different genes (ANK2: c.11791G>A, MYO18B: c.3761G>A), which were also expressed in five relatives. Two family members had showed all indicators of the inherited syndrome including distinct ECG changes and genetic changes.

Conclusion

We describe a distinct inheritable syndrome causing SCD, characterized by specific ECG changes and mutations of ANK2 and MYO18. As far as we know this is the first description of this syndrome.

Post-mortem genetic analysis of sudden unexplained death in a young cohort: a whole-exome sequencing study

Sudden unexplained death (SUD) constitutes a considerable portion of unexpected sudden death in the young. Molecular autopsy has proved to be an efficient diagnostic tool in the multidisciplinary management of SUD. Yet, many cases remain undiagnosed using the widely adopted targeted genetic screening strategies. Here, we investigated the genetic substrates of a young SUD cohort (18-40 years old) from China using whole-exome sequencing (WES), with the primary aim to identify novel SUD susceptibility genes. Within 255 previously acknowledged SUD-associated genes, 21 variants with likely functional effects (pathogenic/likely pathogenic) were identified in 51.9% of the SUD cases. More importantly, a set of 33 candidate genes associated with myopathy were identified to be novel susceptibility genes for SUD. Comparative analysis of the cumulative PHRED-scaled CADD score and polygenetic burden score showed that the amount and deleteriousness of variants in the 255 SUD-associated genes and the 33 candidate genes identified by this study were significantly higher compared with 289 randomly selected genes. A significantly higher genetic burden of rare variants (MAF < 0.1%) in the 33 candidate genes also highlighted putative roles of these genes in SUD. After incorporating these novel genes, the genetic testing yields of the current SUD cohort elevated from 51.9 to 66.7%. Our study expands understanding of the genetic variants underlying SUD and presents insights that improve the utility of genetic screenings.

Can Hot Weather Cause Non-ST Elevation Myocardial Infarction in Young Athletic Male Runners?

Athletes are a group of people who have good activity, regular muscular exercise, an almost standard lifestyle, and should be in good condition with low rates of medical, particularly cardiovascular, complications. However, cardiac attacks, sudden cardiac deaths, and fatal arrhythmogenic syndromes have been reported in athletes with low incidences. We can determine external and internal factors that lead to cardiac attacks in athletes. The former include abnormal cardiac structures and genetics, while the latter include environmental conditions like extreme temperatures, smoking, and drug abuse. Here, we report a case of a cardiac attack with non-ST elevation myocardial infarction (NSTEMI) in a young athlete who was a non-smoker, did not have any abnormal heart structures or a history of drug abuse, and did not have a family history of cardiac disease or arrest. High humidity levels and temperatures were the main causes of the cardiac attack, which occurred during a sports exercise at high temperatures with high humidity levels. We hope to prevent the recurrence of such a case. We need to understand when and where sports exercises can be performed without the risk of medical complications.

Sudden unexplained death versus nonautopsied possible sudden cardiac death: Findings in relatives

BACKGROUND

International guidelines recommend work-up of relatives to autopsy negative sudden cardiac death victims, denoted as sudden unexplained death (SUD) and nonautopsied possible sudden cardiac death (pSCD) victims. This study assesses and compare baseline characteristics and clinical outcome at initial evaluation and during follow-up of relatives to SUD and pSCD victims.

METHODS

We retrospectively included data from systematic screening and routine follow-up of first-degree relatives to SUD and pSCD victims referred to our Unit for Inherited Cardiac Diseases, Copenhagen, 2005-2018. Victims with an antemortem known inherited cardiac disease were excluded.

RESULTS

We included 371 first-degree relatives from 187 families (120 SUD, 67 pSCD): 276 SUD relatives (age 33 ± 18 years, 54% men) and 95 pSCD relatives (age 40 ± 15 years, 51% men). The diagnostic yields of inherited cardiac diseases in SUD and pSCD families were 16% and 13%, respectively (p = .8). The diagnoses in SUD families were mainly channelopathies (68%), whereas pSCD families were equally diagnosed with cardiomyopathies, channelopathies, and premature ischemic heart disease. Ninety-three percent of diagnosed families were diagnosed at initial evaluation and 7% during follow-up (5.4 ± 3.3 years). During follow-up 34% of relatives with a diagnosed inherited cardiac disease had an arrhythmic event, compared to 5% of relatives without established diagnosis (p < .0001).

CONCLUSIONS

Channelopathies dominated in SUD families whereas a broader spectrum of inherited diseases was diagnosed in pSCD families. Most affected relatives were diagnosed at initial evaluation. The event rate was low in relatives without an established diagnosis. Long-term clinical follow-up may not be warranted in all relatives with normal baseline-findings.

Advances in the Molecular Genetics of Catecholaminergic Polymorphic Ventricular Tachycardia

Catecholaminergic polymorphic ventricular tachycardia is a primary arrhythmogenic syndrome with genetic features most commonly seen in adolescents, with syncope and sudden death following exercise or agitation as the main clinical manifestations. The mechanism of its occurrence is related to the aberrant release of Ca²⁺ from cardiomyocytes caused by abnormal RyR2 channels or CASQ2 proteins under conditions of sympathetic excitation, thus inducing a delayed posterior exertional pole, manifested by sympathetic excitation inducing adrenaline secretion, resulting in bidirectional or polymorphic ventricular tachycardia. The mortality rate of the disease is high, but patients usually do not have organic heart disease, the clinical manifestations may not be obvious, and no significant abnormal changes in the QT interval are often observed on electrocardiography. Therefore, the disease is often easily missed and misdiagnosed. A number of genetic mutations have been linked to the development of this disease, and the mechanisms are different. In this paper, we would like to summarize the possible genes related to catecholaminergic polymorphic ventricular tachycardia in order to review the genetic tests currently performed, and to further promote the development of genetic testing techniques and deepen the research on the molecular level of this disease.

Non-ischemic sudden cardiac arrest: Role of 12 lead Holter, family screening and genetic testing

OBJECTIVE AND BACKGROUND

To evaluate the diagnostic and prognostic yield of a comprehensive protocol involving clinical and broad genetic testing in consecutive sudden cardiac arrest (SCA) population. Determining the pathogenesis of non-ischemic SCA is crucial for management and SCA prevention in other family members METHODS: Families with unexplained non-ischemic SCA event underwent rigorous clinical and genetic protocol after referral to our inherited arrhythmia clinic, during 2011-2017.

RESULTS

One hundred and four index cases, 29 ± 16 years, and 421 family members were studied. After a thorough evaluation, diagnosis was made in 80 (77%) of families. The most prevalent 47/104 (45%) diagnosis was inherited channelopathy. The genetic test was positive, in 37 /69 (54%) of patients. Using the Mann Whitney test, we found that electrocardiography (ECG) (effect size 0.5, p < .001), 12 lead Holter (effect size 0.33, p = .001) and family screening (effect size 0.4, p = .001) had the highest yield in reaching the final diagnosis. Family screening, genetic testing, and cardiac MRI were the exclusive modalities for final diagnosis in 14%, 9%, and 2% of families, respectively. Among 421 family members evaluated through cascade screening, 127 (30%), were diagnosed and medically treated. Nine family members from 25 (40%) patients who underwent implantable cardioverter defibrillator (ICD) implantation have experienced appropriate ICD shock.

CONCLUSIONS

A rigorous, systematic protocol in a specialized inherited arrhythmia clinic has a high diagnostic and prognostic yield. ECG, 12 lead Holter and family screening significantly increased the diagnostic yield. In nine families, without genetic testing, the diagnosis would have been missed.

Diagnostic yield in victims of sudden cardiac death and their relatives

AIMS

International guidelines recommend cardiogenetic screening in families with sudden cardiac death (SCD) if the suspected cause is an inherited cardiac disease. The aim was to assess the diagnostic yield of inherited cardiac diseases in consecutively referred SCD families.

METHODS AND RESULTS

In this single-centre retrospective study, we consecutively included families referred to our tertiary unit between 2005 and 2018 for screening due to SCD. Following evaluation of premortem medical records and postmortem findings for the proband, the families underwent a guideline-based screening protocol. Relatives were followed and cardiovascular events registered. In total, 304 families with 695 relatives were included. In probands, mean age at death was 39 years (75% males) and in relatives mean age at screening was 35 years (47% males). The proband-diagnosis was established through autopsy findings (n = 89), genetic analyses (n = 7), or based on premortem findings (n = 21). In the remaining 187 families with borderline/no diagnosis in the proband, screening of relatives yielded a diagnosis in 26 additional families. In total, an inherited cardiac disease was identified in 143 out of 304 families (47%). In relatives, 73 (11%) were diagnosed. Arrhythmogenic right ventricular cardiomyopathy (n = 16) was the most common diagnosis. During follow-up (mean 5.5 years), a low rate of serious cardiac events was observed (no SCD events).

CONCLUSION

Forty-seven percent of SCD families were diagnosed. Eleven percent of the screened relatives received a definite diagnosis and were offered treatment according to guidelines. A low rate of serious cardiovascular events was observed among SCD relatives.

Risk stratification in hypertrophic cardiomyopathy

Sudden cardiac death (SCD) is the most devastating complication of hypertrophic cardiomyopathy (HCM). The greatest challenge in the management of HCM is identifying those at increased risk, since an implantable cardioverter-defibrillator (ICD) is a potentially life-saving therapy. We sought to summarize the available data on SCD in HCM and provide a clinical perspective on the current differing and somewhat conflicting data on risk stratification, with balanced guidance regarding rational clinical decision-making. Additionally, we sought to determine the status of the current implementation of guidelines compiled by HCM experts worldwide. The HCM Risk-SCD model helps improve the risk stratification of HCM patients for primary prevention of SCD by calculating an individual risk estimate that contributes to the clinical decision-making process. Improved risk stratification is important for decision-making before ICD implantation for the primary prevention of SCD.

Multiallelic rare variants support an oligogenic origin of sudden cardiac death in the young

Unexplained sudden death in the young is cardiovascular in most cases. Structural and conduction defects in cardiac-related genes can conspire to underlie sudden cardiac death. Here we report a clinical investigation and an extensive genetic assessment of a Tunisian family with sudden cardiac death in young members. In order to identify the family-genetic basis of sudden cardiac death, we performed Whole Exome Sequencing (WES), read depth copy-number-variation (CNV) screening and segregation analysis. We identify 6 ultra-rare pathogenic heterozygous variants in OBSCN, RYR2, DSC2, AKAP9, CACNA1C and RBM20 genes, and one homozygous splicing variant in TECRL gene consistent with an oligogenic model of inheritance. CNV analysis did not reveal any causative CNV consistent with the family phenotype. Overall, our results are highly suggestive for a cumulative effect of heterozygous missense variants as disease causation and to account for a greater disease severity among offspring. Our study further confirms the complexity of the inheritance of sudden cardiac death and highlights the utility of family-based WES and segregation analysis in the identification of family specific mutations within different cardiac genes pathways.

European recommendations integrating genetic testing into multidisciplinary management of sudden cardiac death

Sudden cardiac death (SCD) accounts for 10-20% of total mortality, i.e., one in five individuals will eventually die suddenly. Given the substantial genetic component of SCD in younger cases, postmortem genetic testing may be particularly useful in elucidating etiological factors in the cause of death in this subset. The identification of genes responsible for inherited cardiac diseases have led to the organization of cardiogenetic consultations in many countries worldwide. Expert recommendations are available, emphasizing the importance of genetic testing and appropriate information provision of affected individuals, as well as their relatives. However, the context of postmortem genetic testing raises some particular ethical, legal, and practical (including economic or financial) challenges. The Public and Professional Policy Committee of the European Society of Human Genetics (ESHG), together with international experts, developed recommendations on management of SCD after a workshop sponsored by the Brocher Foundation and ESHG in November 2016. These recommendations have been endorsed by the ESHG Board, the European Council of Legal Medicine, the European Society of Cardiology working group on myocardial and pericardial diseases, the ERN GUARD-HEART, and the Association for European Cardiovascular Pathology. They emphasize the importance of increasing the proportion of both medical and medicolegal autopsies and educating the professionals. Multidisciplinary collaboration is of utmost importance. Public funding should be allocated to reach these goals and allow public health evaluation.

Coxsackievirus B infection induces the extracellular release of miR-590-5p, a proviral microRNA

Coxsackievirus B is a significant human pathogen and is a leading cause of myocarditis. We and others have observed that certain enteroviruses including coxsackievirus B cause infected cells to shed extracellular vesicles containing infectious virus. Recent reports have shown that vesicle-bound virus can infect more efficiently than free virus. Though microRNAs are differentially regulated in cells following infection, few have been associated with the vesicles shed from infected cells. Here we report exclusive trafficking of specific microRNAs into viral vesicles compared to vesicles from non-infected cells. We found that the most highly-expressed unique microRNA in viral vesicles was miR-590-5p, which facilitates prolonged viral replication by blocking apoptotic factors. Cells over-expressing this miR were significantly more susceptible to infection. This may be a mechanism by which coxsackievirus B boosts subsequent rounds of infection by co-packaging virus and a select set of pro-viral microRNAs in extracellular vesicles.

Sudden unexplained death in the young: epidemiology, aetiology and value of the clinically guided genetic screening

Aims

To determine the incidence and the causes of sudden death (SD) in persons aged 1-35 years old and the diagnostic yield of clinically guided genetic screening in the sudden arrhythmic death syndrome (SADS) victims' families.

Methods and results

Incidence and causes of SD in the Attica region of Greece in 2002-10 were determined using death certificates and autopsy reports. We evaluated clinically consecutive families of SADS victims and if a clinical diagnosis was established, we proceeded to targeted genetic analysis. Out of 6030 deaths, 56% were due to traumatic or violent causes, 40.5% were natural deaths, and 3.3% were of undetermined cause. There were 349 SD cases. Cardiovascular causes accounted for 65%, non-cardiovascular causes for 17%, and SADS for 18%. Clinical evaluation identified an inherited heart disease in 5/20 SADS families (25%). Targeted genetic analysis identified a causative mutation in all of the five screened families and reconfirmed the diagnosis in three of five proband victims. Clinical and genetic evaluation of 28 family members identified eight affected carriers and eight non-affected carriers. Molecular autopsy failed to identify any of these families.

Conclusion

Sudden death in the young is of cardiovascular origin in the majority of cases. A considerable rate of SD cases remains of unknown cause on post-mortem. Apart from channelopathies, subclinical forms of inherited structural heart diseases would appear to be implicated in SADS. Clinically guided genetic screening has a significant diagnostic yield and identifies affected families that would have been missed by the current suggested molecular autopsy panel.

Ictal Asystole in Temporal Lobe Epilepsy: A Possible Cause of Sudden Unexplained Death - A Case Report

We report a case of a 47-year-old woman who presented with a 3-year history of paroxysmal events after suffering traumatic brain injury in a motor vehicle accident. She had not previously been diagnosed with epilepsy. On video-EEG monitoring, she was found to have a right temporal seizure associated with ictal asystole lasting for 18 seconds. Our case raises the possibility that undiagnosed ictal asystole could be a potential cause of sudden unexplained death.

Post-Mortem Imaging Adjudicated Sudden Death: Causes and Controversies

Sudden cardiac death (SCD) is a catastrophic complication of many cardiac conditions often occurring without warning. In these cases, a post-mortem examination is required to elucidate the cause of death and is regarded as the 'gold standard'. However, in circumstances of certain religious/cultural beliefs and advanced body decomposition an alternative non-invasive approach would be preferred. Although a developing field, post-mortem imaging using computed tomography (pmCT) or magnetic resonance imaging (pmMR) provides a non-invasive and accurate alternative to traditional post-mortem in specific circumstances. In particular, pmMR has an important role in younger decedents while pmCT is more suited to examination of adults with SCD. Despite encouraging results from several preliminary studies, more research is needed to determine the most appropriate role for post-mortem imaging in the clinical algorhythm for investigation of SCD.

Ion Channel Disorders and Sudden Cardiac Death

Long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia are inherited primary electrical disorders that predispose to sudden cardiac death in the absence of structural heart disease. Also known as cardiac channelopathies, primary electrical disorders respond to mutations in genes encoding cardiac ion channels and/or their regulatory proteins, which result in modifications in the cardiac action potential or in the intracellular calcium handling that lead to electrical instability and life-threatening ventricular arrhythmias. These disorders may have low penetrance and expressivity, making clinical diagnosis often challenging. However, because sudden cardiac death might be the first presenting symptom of the disease, early diagnosis becomes essential. Genetic testing might be helpful in this regard, providing a definite diagnosis in some patients. Yet important limitations still exist, with a significant proportion of patients remaining with no causative mutation identifiable after genetic testing. This review aims to provide the latest knowledge on the genetic basis of cardiac channelopathies and discuss the role of the affected proteins in the pathophysiology of each one of these diseases.

Sudden unexplained cardiac deaths in young adults: a call for multidisciplinary approach

The investigation of death in young (<35 years), previously fit individuals, calls for a detailed autopsy with emphasis placed upon the examination of the heart. In most instances, the cause of cardiac death can be identified during autopsy. However, a large percentage of sudden deaths remain unexplained even after comprehensive medicolegal investigation, including autopsy, and are labelled as autopsy-negative sudden unexplained cardiac death (SUD). Still, when you look to the law, an autopsy, a much needed truth-finding-instrument, usually is not mandatory and is left up to the discretion of various medical or legal authorities, which when making a decision, balance various, often conflicting interests of the state and society on the one hand and of the deceased and his family on the other. Cardiac molecular autopsy calls for a close cooperation between medical examiner, pathologist, family physician, cardiologist, geneticist, and the relatives. Multidisciplinary approach and the identification of genetic cause of SUD enable proper genetic counselling for surviving relatives as well as for implementing specific preventive/therapeutic strategies, e.g. implantable cardioverter-defibrillator (ICD) implantation.

Sudden unexpected death caused by stroke: A nationwide study among children and young adults in Denmark

Background

Stroke is the fifth leading cause of death in young individuals globally. Data on the burden of sudden death by stroke are sparse in the young.

Aims

The aim of this study was to report mortality rates, cause of death, stroke subtype, and symptoms in children and young adults who suffered sudden death by stroke.

Methods

We conducted a retrospective, nationwide study including all deaths within Danish borders between 2000–2009 and 2007–2009 in persons aged 1–35 years and 36–49 years, respectively. Two physicians identified all sudden death cases through review of all death certificates. All available autopsy reports and records from hospitals and general practitioners were retrieved and a neurologist identified all sudden death by stroke cases.

Results

Of the 14,567 deaths in the 10-year period, there were 1,698 sudden death cases, of which 52 (3%) were sudden death by stroke. There was a male predominance (56%) and the median age was 33 years. The incidence of sudden death by stroke in individuals aged 1–49 years was 0.19 deaths per 100,000 person-years. Stroke was hemorrhagic in 94% of cases, whereof subarachnoid hemorrhage was the cause of death in 63% of cases. Seventeen (33%) cases contacted the healthcare system because of neurological symptoms, whereof one was suspected of having a stroke (6%).

Conclusions

Sudden death by stroke in children and young adults occurs primarily due to hemorrhagic stroke. We report a high frequency of neurological symptoms prior to sudden death by stroke. Increased awareness among healthcare professionals towards stroke symptoms in children and young adults may lead to earlier detection of stroke, and thereby potentially lowering the incidence of sudden death by stroke.

Prevention of Sudden Cardiac Death in Children and Young Adults

In the present review, we summarize current approaches to the prevention of sudden cardiac death (SCD) in children and young adults, focusing on age less than 35 years. SCD in the young is rare, but devastating from the societal perspective. While coronary artery disease is the main etiology of SCD in the older age groups, conditions such as cardiomyopathies and electrical channelopathies are more likely to be found in the young. In the majority of younger cases, cardiac arrest can be the first recognized manifestation of the underlying cardiac pathology, although some have experienced cardiovascular symptoms prior to the SCD. Since identification of a cardiac disease is pivotal for implementation of appropriate preventive measures, measures such as electrocardiographic screening in subpopulations such as athletes have been proposed. However, these efforts are impeded by the large number of individuals needed to test in order to find one with cardiac disease, leading to significant rates of false positive findings and high costs. When a high-risk cardiac condition is identified in a young person, measures of lifestyle modification, appropriate medical treatment and ICD implantation in selected individuals based on risk stratification are warranted. Nevertheless, the benefits of lifelong ICD therapy need to be balanced with long-term complications and quality of life.

Screening high school students in Italy for sudden cardiac death prevention by using a telecardiology device: a retrospective observational study

BACKGROUND

In 2010, an Italian project was launched aimed at using a telecardiology device in order to perform early diagnosis of young students at risk of sudden cardiac death.

METHODS

Our retrospective observational study was conducted on a population of 13,016 students, aged between 16 and 19 years, in different Italian regions. It consisted of analysis of data recorded during a telecardiology pilot study. The recorded data were electrocardiograms and data concerning lifestyle habits and family history of cardiovascular diseases. In total, 14 alterations in the electrocardiogram signal have been considered in this study. Some of these alterations are as follows: ventricular ectopic beats, atrioventricular block, Brugada-like electrocardiogram pattern, left anterior/posterior fascicular block, left/right ventricular hypertrophy, long/short QT interval, left atrial enlargement, right atrial enlargement, short PQ interval, and ventricular pre-excitation Wolff-Parkinson-White syndrome. On the basis of the collected data, we implemented this retrospective observational study.

RESULTS

The analysed data showed that 13.60% of students had a family history for cardiovascular diseases, 22.43% reported smoking habits, 26.23% reported alcohol consumption, and 7.24% reported abuse of drugs. A total of 24% of students had at least one of the 14 electrocardiogram pathological alterations considered in our study and 32% had electrocardiogram values within the normal range.

CONCLUSIONS

This retrospective observational study analysed data registered during our telecardiology activity. This activity permitted to maximise data collection and minimise the costs for collecting such data. This activity of screening is being continued and in the next few years it will allow us to have a greater mass of data.

Molecular and Functional Characterization of Rare CACNA1C Variants in Sudden Unexplained Death in the Young

INTRODUCTION

Perturbations in the CACNA1C-encoded L-type calcium channel α-subunit have been linked recently to heritable arrhythmia syndromes, including Timothy syndrome, Brugada syndrome, early repolarization syndrome, and long QT syndrome. These heritable arrhythmia syndromes may serve as a pathogenic basis for autopsy-negative sudden unexplained death in the young (SUDY). However, the contribution of CACNA1C mutations to SUDY is unknown.

OBJECTIVE

We set out to determine the spectrum, prevalence, and pathophysiology of rare CACNA1C variants in SUDY.

METHODS

Mutational analysis of CACNA1C was conducted in 82 SUDY cases using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct sequencing. Identified variants were engineered using site-directed mutagenesis, and heterologously expressed in TSA-201 or HEK293 cells.

RESULTS

Two SUDY cases (2.4%) harbored functional variants in CACNA1C. The E850del and N2091S variants involve highly conserved residues and localize to the II-III linker and C-terminus, respectively. Although observed in publically available exome databases, both variants confer abnormal Ca_V 1.2 electrophysiological characteristics. Examination of the electrophysiological properties revealed the E850del mutation in CACNA1C led to a 95% loss-of-function in I_Ca , and the N2091S variant led to a 105% gain-of-function in I_Ca. Additionally, N2091S led to minor kinetic alterations including a -3.4 mV shift in V_1/2 of activation.

CONCLUSION

This study provides molecular and functional evidence that rare CACNA1C genetic variants may contribute to the underlying pathogenic basis for some cases of SUDY in either a gain or loss-of-function mechanism.

Post-mortem whole-exome sequencing (WES) with a focus on cardiac disease-associated genes in five young sudden unexplained death (SUD) cases

Sudden death of healthy young adults in the absence of any medical reason is generally categorised as autopsy-negative sudden unexplained death (SUD). Approximately 30 % of all SUD cases can be explained by lethal sequence variants in cardiac genes causing disturbed ion channel functions (channelopathies) or minimal structural heart abnormalities (cardiomyopathies). The aim of this study was to perform whole-exome sequencing (WES) in five young SUD cases in order to identify potentially disease-causing mutations with a focus on 184 genes associated with cardiac diseases or sudden death. WES analysis enabled the identification of damaging-predicted cardiac sequence alterations in three out of five SUD cases. Two SUD victims carried disease-causing variants in long QT syndrome (LQTS)-associated genes (KCNH2, SCN5A). In a third case, WES identified variants in two genes involved in mitral valve prolapse and thoracic aortic aneurism (DCHS1, TGFβ2). The genome of a fourth case carried several minor variants involved in arrhythmia pointing to a multigene influence that might have contributed to sudden death. Our results confirm that post-mortem genetic testing in SUD cases in addition to the conventional autopsy can help to identify familial cardiac diseases and can contribute to the identification of genetic risk factors for sudden death.

ICD Therapy for Primary Prevention in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common and heterogeneous disorder that increases an individual's risk of sudden cardiac death (SCD). This review article discusses the relevant factors that are involved in the challenge of preventing SCD in patients with HCM. The epidemiology of SCD in patients is reviewed as well as the structural and genetic basis behind ventricular arrhythmias in HCM. The primary prevention of SCD with implantable cardioverter-defibrillator (ICD) therapy is the cornerstone of modern treatment for individuals at high risk of SCD. The focus here is on the current and emerging predictors of SCD as well as risk stratification recommendations from both North American and European guidelines. Issues related to ICD implantation, such as programming, complications and inappropriate therapies, are discussed. The emerging role of the fully subcutaneous ICD and the data regarding its implantation are reviewed.

Elevated Ca2+ transients and increased myofibrillar power generation cause cardiac hypercontractility in a model of Noonan syndrome with multiple lentigines

Noonan syndrome with multiple lentigines (NSML) is primarily caused by mutations in the nonreceptor protein tyrosine phosphatase SHP2 and associated with congenital heart disease in the form of pulmonary valve stenosis and hypertrophic cardiomyopathy (HCM). Our goal was to elucidate the cellular mechanisms underlying the development of HCM caused by the Q510E mutation in SHP2. NSML patients carrying this mutation suffer from a particularly severe form of HCM. Drawing parallels to other, more common forms of HCM, we hypothesized that altered Ca(2+) homeostasis and/or sarcomeric mechanical properties play key roles in the pathomechanism. We used transgenic mice with cardiomyocyte-specific expression of Q510E-SHP2 starting before birth. Mice develop neonatal onset HCM with increased ejection fraction and fractional shortening at 4-6 wk of age. To assess Ca(2+) handling, isolated cardiomyocytes were loaded with fluo-4. Q510E-SHP2 expression increased Ca(2+) transient amplitudes during excitation-contraction coupling and increased sarcoplasmic reticulum Ca(2+) content concurrent with increased expression of sarco(endo)plasmic reticulum Ca(2+)-ATPase. In skinned cardiomyocyte preparations from Q510E-SHP2 mice, force-velocity relationships and power-load curves were shifted upward. The peak power-generating capacity was increased approximately twofold. Transmission electron microscopy revealed that the relative intracellular area occupied by sarcomeres was increased in Q510E-SHP2 cardiomyocytes. Triton X-100-based myofiber purification showed that Q510E-SHP2 increased the amount of sarcomeric proteins assembled into myofibers. In summary, Q510E-SHP2 expression leads to enhanced contractile performance early in disease progression by augmenting intracellular Ca(2+) cycling and increasing the number of power-generating sarcomeres. This gives important new insights into the cellular pathomechanisms of Q510E-SHP2-associated HCM.

Utility of the exercise electrocardiogram testing in sudden cardiac death risk stratification

BACKGROUND

Sudden cardiac death (SCD) remains a major public health problem. Current established criteria identifying those at risk of sudden arrhythmic death, and likely to benefit from implantable cardioverter defibrillators (ICDs), are neither sensitive nor specific. Exercise electrocardiogram (ECG) testing was traditionally used for information concerning patients' symptoms, exercise capacity, cardiovascular function, myocardial ischemia detection, and hemodynamic responses during activity in patients with hypertrophic cardiomyopathy.

METHODS

We conducted a systematic review of MEDLINE on the utility of exercise ECG testing in SCD risk stratification.

RESULTS

Exercise testing can unmask suspected primary electrical diseases in certain patients (catecholaminergic polymorphic ventricular tachycardia or concealed long QT syndrome) and can be effectively utilized to risk stratify patients at an increased (such as early repolarization syndrome and Brugada syndrome) or decreased risk of SCD, such as the loss of preexcitation on exercise testing in asymptomatic Wolff-Parkinson-White syndrome.

CONCLUSIONS

Exercise ECG testing helps in SCD risk stratification in patients with and without arrhythmogenic hereditary syndromes.

Improving usual care after sudden death in the young with focus on inherited cardiac diseases (the CAREFUL study): a community-based intervention study

AIMS

Inherited cardiac diseases play an important role in sudden death (SD) in the young. Autopsy and cardiogenetic evaluation of relatives of young SD victims identifies relatives at risk. We studied the usual care after SD in the young aimed at identifying inherited cardiac disease, and assessed the efficacy of two interventions to improve this usual care.

METHODS AND RESULTS

We conducted a community-based intervention study to increase autopsy rates of young SD victims aged 1-44 years and referral of their relatives to cardiogenetic clinics. In the Amsterdam study region, a 24/7 central telephone number and a website were available to inform general practitioners and coroners. In the Utrecht study region, they were informed by a letter and educational meetings. In two control regions usual care was monitored. Autopsy was performed in 169 of 390 registered SD cases (43.3%). Cardiogenetic evaluation of relatives was indicated in 296 of 390 cases (75.9%), but only 25 of 296 families (8.4%) attended a cardiogenetics clinic. Autopsy rates were 38.7% in the Amsterdam study region, 45.5% in the Utrecht study region, and 49.0% in the control regions. The proportion of families evaluated at cardiogenetics clinics in the Amsterdam study region, the Utrecht study region, and the control regions was 7.3, 9.9, and 8.8%, respectively.

CONCLUSIONS

The autopsy rate in young SD cases in the Netherlands is low and few families undergo cardiogenetic evaluation to detect inherited cardiac diseases. Two different interventions did not improve this suboptimal situation substantially.

Comparison of conventional autopsy and magnetic resonance imaging in determining the cause of sudden death in the young

BACKGROUND

Sudden death in the young is a tragic complication of a number of medical diseases. There is limited data regarding the utility of post-mortem Magnetic Resonance (MR) imaging and Computer Tomography (CT) scanning in determining the cause of sudden death. This study sought to compare the accuracy of post-mortem cross-sectional imaging (MR and CT) with the conventional autopsy in determining the cause of sudden death in the young.

METHODS

Consecutive patients from 2010 to 2012 (aged 1-35 years) who had sudden death were included. Patients were scanned by CT and 1.5 T MR imaging prior to the conventional autopsy being performed. The primary outcome was diagnostic congruence between imaging and conventional autopsy.

RESULTS

In 17 patients studied, the mean age at death was 23 ± 11 years, with a male predominance (n = 12; 71%). The most common cause of death was a primary cardiac pathology (n = 8; 47%), including ARVC (24%) and ischemic heart disease (12%). Non-cardiac causes identified included pulmonary embolism (6%), and aortic dissection (6%). MR imaging correctly identified the diagnosis in 12 patients who subsequently had positive findings at conventional autopsy, while the diagnosis in the remaining 5 cases remained unexplained. MR imaging was found to be highly sensitive (100%) with a high negative (100%) and positive (80%) predictive value.

CONCLUSIONS

Dedicated post-mortem MR imaging of the heart and brain is a useful modality in determining the cause of sudden death in children and young adults, particularly in situations where a conventional autopsy cannot be performed for logistic, cultural or personal reasons.

Sudden unexplained death in infants and children: the role of undiagnosed inherited cardiac conditions

Sudden unexplained death in childhood is a traumatic event for both the immediate family and medical professionals. This is termed sudden unexplained or arrhythmic death syndrome (SUDS/SADS) for children over 1 year of age while sudden unexplained death in infancy or sudden infant death syndrome (SUDI/SIDS) refers to unexplained deaths in the first year of life. There is increasing evidence for the role of undiagnosed inherited cardiac conditions, particularly channelopathies, as the cause of these deaths. This has far-reaching implications for the family regarding the potential risk to other family members and future pregnancies, providing a challenge not only in the counselling but also in the structured assessment and management of immediate relatives. This review will discuss the cardiac risk involved in sudden unexplained deaths of infants and children, the role of molecular autopsy, family cardiological screening, current management strategies, and future directions in this area.

A case control study on autopsy findings in sudden unexplained nocturnal death syndrome

AIM

Sudden unexplained nocturnal death syndrome (SUNDS) has been linked to the Brugada syndrome. In some places, acute haemorrhagic pancreatitis is widely held to cause it. We conducted a systematic, controlled autopsy study on Filipino SUNDS victims to rule out structural heart findings as well as acute haemorrhagic pancreatitis as causes.

METHODS AND RESULTS

A case control autopsy study was conducted comparing SUNDS victims between 18 and 50 years of age who died within 1 h of symptom onset with age- and gender-matched controls. There were 24 SUNDS (mean age 34.5 years) and 24 controls (mean 32.7 years). The autopsy incidence of structural heart disease was 8.3% (95% CI (1% to 27%)) and focal pancreatic haemorrhage was 4.17% (95% CI (0.1% to 20%)) but zero for true acute haemorrhagic pancreatitis among SUNDS victims. Autopsy findings in SUNDS versus controls were not significantly different from each other, showing no diagnostic abnormality in any of the organs. There was no significant difference in the incidence of acute haemorrhagic pancreatitis in both the SUNDS and control groups. We did not find fetal dispersion of the atrioventricular (AV) node, sclerosis or fibrosis of the AV conduction system, in a substudy of SUNDS cases.

CONCLUSIONS

We have shown that there is no significant difference in the overall autopsy findings between SUNDS and controls. Autopsy findings were normal in 70% of SUNDS; no cardiac structural pathology was found in 87% of cases. Haemorrhagic pancreatitis is the cause of death in a minority of SUNDS. The cardiac conduction system is normal in a subgroup of SUNDS studied.

Experiences, considerations and emotions relating to cardiogenetic evaluation in relatives of young sudden cardiac death victims

Relatives of young sudden cardiac death (SCD) victims are at increased risk of carrying a potentially fatal inherited cardiac disease. Hence, it is recommended to perform an autopsy on the victim and to refer his or her relatives to a cardiogenetics clinic for a full evaluation to identify those at risk and allow preventive measures to be taken. However, at present, the number of families attending a cardiogenetics clinic after the SCD of a young relative is low in the Netherlands. We performed a qualitative study and report on the experiences and attitudes of first-degree relatives who attended a cardiogenetics clinic for evaluation. In total, we interviewed nine first-degree relatives and one spouse of seven SCD victims about their experiences, considerations and emotions before attendance and at the first stage of the cardiogenetic evaluation before DNA results were available. Interviews were transcribed verbatim and analysed. Medical professionals did not have an important role in informing or referring relatives to a cardiogenetics clinic. Importantly, all participants indicated that they would have appreciated a more directive approach from medical professionals, because their mourning process hampered their own search for information and decision-making. A need to understand the cause of death and wanting to prevent another SCD event occurring in the family were the most important reasons for attending a clinic. There are possibilities to improve the information process and better support their decision-making. The multidisciplinary cardiogenetic evaluation was appreciated, but could be improved by minor changes in the way it is implemented.