Sudden cardiac death in 15-35-year olds in Sweden during 1992-99

Autopsy of all young sudden death cases is important to increase survival in family members left behind

Sudden cardiac death (SCD) is an important public health problem worldwide, accounting for an estimated 6-20% of total mortality. A significant proportion of SCD is caused by inherited heart disease, especially among the young. An autopsy is crucial to establish a diagnosis of inherited heart disease, allowing for subsequent identification of family members who require cardiac evaluation. Autopsy of cases of unexplained sudden death in the young is recommended by both the European Society of Cardiology and the American Heart Association. Overall autopsy rates, however, have been declining in many countries across the globe, and there is a lack of skilled trained pathologists able to carry out full autopsies. Recent studies show that not all cases of sudden death in the young are autopsied, likely due to financial, administrative, and organizational limitations as well as awareness among police, legal authorities, and physicians. Consequently, diagnoses of inherited heart disease are likely missed, along with the opportunity for treatment and prevention among surviving relatives. This article reviews the evidence for the role of autopsy in sudden death, how the cardiologist should interpret the autopsy-record, and how this can be integrated and implemented in clinical practice. Finally, we identify areas for future research along with potential for healthcare reform aimed at increasing autopsy awareness and ultimately reducing mortality from SCD.

Risk factors of sudden cardiac death in Egyptian patients younger than 40 years

BACKGROUND

Sudden cardiac death in young people is a major problem. The causes are well known; however, they may not be discovered before the episode of sudden death. A challenge for the future is identifying patients at risk before an episode of sudden cardiac death. Development of preventive and educational programs is required to identify sudden cardiac death/sudden cardiac arrest (SCD/SCA) risk factors, causes and characteristics. We aimed to study the characteristics of SCD/SCA in a cohort of young Egyptian population. Our retrospective cohort study included 246 patients of SCD/SCA who were collected from 5000 records of arrhythmia patients from January 2010 till January 2020. The records of the specialized arrhythmia clinic were reviewed to collect the families of SCD/SCA. All patients and/or their first-degree relatives were subjected to thorough history taking and clinical evaluation and investigations. Comparisons were done regarding age group and presence of positive family history of SCD.

RESULTS

Males constituted 56.9% of the study population. Mean age was 26.6 ± 12.73 years. Positive family history was present in 202 (82.1%) cases. Sixty-one percent of the cases had history of syncopal attacks. SCD/SCA during non-exertion or sleep occurred in 50.4% of cases. Hypertrophic cardiomyopathy was the most common cause of SCD/SCA (20.3%), followed by dilated cardiomyopathy (19.1%), long QT Syndrome (11.4%), complete heart block (8.5%), and Brugada syndrome (6.8%). In the older age group of 18-40 years, hypertrophic cardiomyopathy was responsible for SCD in 44 patients (25.3%) versus 6 patients (8.3%) in younger age group (p-value: 0.003). DCM was also dominant in older age group (42 patients; 24.1%) versus 5 patients (6.9%) in younger age group. Hypertrophic cardiomyopathy was more prevalent in positive family history group (46 patients; 22.8%) versus 4 patients (9.1%) in negative family history group (p-value: 0.041).

CONCLUSION

Family history of SCD was the most common risk factor of SCD. The most common cause of SCD in young Egyptian patients below 40 years was hypertrophic cardiomyopathy, followed by dilated cardiomyopathy. Both diseases were more common in the age group between 18 and 40 years. Hypertrophic cardiomyopathy was more common in patients with positive family history of SCD/SCA.

Cohort profile: the Swedish study of SUDden cardiac Death in the Young (SUDDY) 2000-2010: a complete nationwide cohort of SCDs

PURPOSE

The rationale behind the SUDden cardiac Death in the Young (SUDDY) cohort was to provide a complete nationwide, high-quality platform with integrated multisource data, for clinical and genetic research on sudden cardiac death (SCD) in the young, with the ultimate goal to predict and prevent SCD.

PARTICIPANTS

The cohort contains all SCD victims <36 years, in Sweden during the period 2000-2010. We assigned five population-based controls per case, together with parents of cases and controls, in total 15 633 individuals. Data of all individuals were extracted from multiple mandatory registries; the National Patient Registry, the Medical Birth Registry, the Prescribed Drug registry, the Cause of Death registry, the Multigeneration Registry, combined with socioeconomic data from Statistics Sweden. From SCD victims, the autopsy report, medical records, ECGs, parental information and biological samples were gathered.

FINDINGS TO DATE

We identified 903 individuals diagnosed with SCD (67% men, 33% women). The cases comprised 236 infants <1 year of age (26%), 90 individuals aged 1-15 years (10%), 186 individuals aged 15-25 years (21%) and 391 aged 25-35 years (43%). Hospitalisations and outpatient clinic visits due to syncope were significantly more common among cases than controls. DNA obtained from dried blood spots tests (DBS) stored from birth was equally suitable as venous blood samples for high-throughput genetic analysis of SCD cases.

FUTURE PLANS

We will explore the SUDDY cohort for symptoms and healthcare consumption, socioeconomic variables and family history of SCD. Furthermore, we will perform whole exome sequencing analysis on DNA of cases obtained from DBS or postmortem samples together with parental blood samples in search for gene variants associated with cardiac disease. The genetic analysis together with data compiled in the nationwide cohort is expected to improve current knowledge on the incidence, aetiology, clinical characteristics and family history of SCD.

Natural Causes of Sudden Young Adult Deaths in Forensic Autopsies

Objective The aim of this study is to define epidemiologic differences and the most common pathologies that cause nontraumatic sudden, natural death in people in the age group of 18-35 years. Identifying causes of sudden death in this age group is important for determining approaches for prevention. Methods We performed a descriptive statistical methodology, analysis, and interpretation using demographic and autopsy data of sudden deaths. A total of 4034 autopsies were reviewed and 66 cases of sudden death were included in this study.  Results We identified 58 (87.9%) subjects in whom the adjudicated cause of death was of potential cardiac etiology. The most common cause of sudden young adult death was ischemic heart disease associated with the atherosclerotic coronary artery (n=24, 36.3%), followed by ischemic heart disease associated with nonatherosclerotic coronary artery disease and dissecting aortic aneurysm. Conclusion We put forth that the main cause of sudden young adult death was cardiac (87.9%) in origin. Of these cardiac causes, ischemic etiology associated with atherosclerosis was the main reason for sudden young adult deaths. In order to reduce the incidence of sudden young adult deaths, major efforts should be directed to prevent atherosclerosis in this age group.

[Adult advanced life support]

These European Resuscitation Council Advanced Life Support guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

Ischemic Heart Disease Related Sudden Cardiac Death in Autopsied Cases: An Egyptian perspective

ABSTRACT

Diagnosis of the underlying cause of sudden unexpected death in a previously healthy individual remains one of the important challenges in forensic practice. Ischemic heart disease is the most common cause of sudden death. The current study aims to investigate the incidence and pathology of sudden ischemic cardiac death in Egypt. All cases of sudden cardiac death (SCD) examined by different forensic departments throughout Egypt during the period of January 2010 through December 2014 were included. Cases underwent complete autopsy examination including a thorough gross and microscopic examination of the heart and great blood vessels. Of 535 cases of SCD diagnosed during the period of the study, coronary atherosclerosis was the principle finding in 420 (78.5%) cases. The highest numbers of deaths were reported in fifth and sixth decades with male preference. Other causes of SCD included myocarditis, cardiomyopathies, valvular heart disease, and hypertensive heart disease (7.8%, 4.1%, 4.1%, and 2.8%, respectively). There was severe stenosis (>75%) of at least 1 coronary artery in 74% of cases. Type VI atherosclerosis was found in 40.7% of cases. The left anterior descending branch was the most affected artery by atherosclerosis. Acute coronary pathological events were demonstrated in 27.6% of cases. Recent myocardial infarction was evident in 55.5% of cases, whereas old infarcts were demonstrated in 44.5% of cases. Features of hypertensive heart disease were present in 18.3% of cases. In conclusion, ischemic heart disease is the leading cause of SCD in Egypt.

European Resuscitation Council Guidelines 2021: Adult advanced life support

These European Resuscitation Council Advanced Life Support guidelines, are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

Sudden Death and Coronary Artery Anomalies

Congenital coronary artery anomalies (CAA) include a wide spectrum of malformations present at birth with various clinical manifestations and degrees of severity. Patients may be asymptomatic, and CAA may be an incidental finding during cardiac imaging or at autopsy. However, in other cases, ischemia-related signs and symptoms, leading to an increased risk of sudden cardiac death (SCD), often as first presentation may occur. In this chapter, we discuss the normal anatomy of the coronary arteries (CA) and the pathology of CAA at risk of SCD, including our experience with victims of SCD among the young population (age <40 years) and among athletes.

Incidence of sudden cardiac death in the young: a systematic review

OBJECTIVE

To summarise studies describing incidence of sudden cardiac death in a general population of young individuals to inform screening policy.

DESIGN

Systematic review.

DATA SOURCES

Database searches of MEDLINE, EMBASE and the Cochrane library (all inception to current) on 29 April 2019 (updated 16 November 2019), and forward/backward citation tracking of eligible studies.

STUDY ELIGIBILITY CRITERIA

All studies that reported incidence of sudden cardiac death in young individuals (12-39 years) in a general population, with no restriction on language or date. Planned subgroups were incidence by age, sex, race and athletic status (including military personnel).

DATA EXTRACTION

Two reviewers independently assessed study eligibility, extracted study data and assessed risk of bias using the Joanna Briggs Institute critical appraisal checklist for prevalence studies.

ANALYSIS

Reported incidence of sudden cardiac death in the young per 100 000 person-years.

RESULTS

38 studies that reported incidence across five continents. We identified substantial heterogeneity in population, sudden cardiac death definition, and case ascertainment methods, precluding meta-analysis. Median reported follow-up years was 6.97 million (IQR 2.34 million-23.70 million) and number of sudden cardiac death cases was 64 (IQR 40-251). In the general population, the median of reported incidence was 1.7 sudden cardiac death per 100 000 person-years (IQR 1.3-2.6, range 0.75-11.9). Most studies (n=14, 54%) reported an incidence between one and two cases per 100 000 person-years. Incidence was higher in males and older individuals.

CONCLUSIONS

This systematic review identified variability in the reported incidence of sudden cardiac death in the young across studies. Most studies reported an incidence between one and two cases per 100 000 person-years.

PROSPERO REGISTRATION NUMBER

CRD42019120563.

Unexpected High Prevalence of Cardiovascular Disease Risk Factors and Psychiatric Disease Among Young People With Sudden Cardiac Arrest

Background

It is believed that most sudden cardiac arrests (SCAs) in young people occur in previously healthy people with rare risk factors for sudden death. Few studies have investigated large populations with complete ascertainment. Our objective was to use multisource records to identify and classify all out‐of‐hospital cardiac arrests in the Greater Toronto Area (population 6.6 million) in people aged 2 to 45 years from 2009 to 2012.

Methods and Results

Expert reviewers employed a systematic process, with emergency medical services, in‐hospital and coroner records, to adjudicate the cause of death as SCA from cardiac or noncardiac causes. We report the adjudicated etiologies, circumstances, triggers, and characteristics of the SCA cohort. Of 2937 eligible out‐of‐hospital cardiac arrest cases, 608 (20.7%) SCAs had an adjudicated etiology of cardiac cause (120 survivors and 488 nonsurvivors). Two thirds of these SCA patients had a history of cardiovascular disease, and over 50% had been diagnosed with ≥1 cardiovascular disease risk factor. Moreover, 20.1% of SCAs were diagnosed with psychiatric disease and 30% had central nervous system drugs prescribed. Over 30% of SCA patients had central nervous system active drugs, including drugs of abuse detected postmortem, with opioids and ethanol being detected most frequently. Potentially heritable structural cardiac diseases accounted for only 6.9% of SCA events, with acquired cardiac diseases comprising the rest.

Conclusions

The underlying causes of SCA, in people aged 2 to 45 years, often occur in those with previously diagnosed cardiovascular diseases, and are associated with contributory factors including prescribed medications, recreational drugs, and a concomitant psychiatric history.

See Editorial by Atkins

Exercise related sudden cardiac death (SCD) in the young - Pre-mortal characterization of a Swedish nationwide cohort, showing a decline in SCD among athletes

AIMS

To study the frequency, etiology, and premortal abnormalities in exercise-related sudden cardiac death (SCD) in the young in Sweden.

METHODS

All subjects with SCD in 10-35-year olds in Sweden during 2000-10, were included (n = 514). Information about each case was retrieved from death certifications, autopsy- and medical records. The number of SCD in athletes was compared to national figures from 1992-99.

RESULTS

Exercise-related SCD occurred in 12% (62/514) of the SCD-population, a majority being men (56/62; 90%). Cardiopulmonary resuscitation (CPR) was started in 87% (54/62). In total, 48% (30/62), had a cardiac diagnosis, symptoms, family history and/or ECG-changes, before the fatal event. The most prevalent autopsy diagnosis was sudden arrhythmic death syndrome (15/62; 24%). The frequency of hypertrophic cardiomyopathy (HCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC) was significantly higher in exercise-related SCD compared to non-exertional SCD. Exercise-related SCD was more common in athletes (21/29) than in non-athletes (41/485) (P < 0.0001). The total number of SCDs/year in athletes 15-35 years old, are approximately halved in 2000-10 compared to the years 1992-99.

CONCLUSION

The increased risk of exercise-related SCD in HCM and ARVC underlines the importance of early detection and eligibility recommendations. There is a major reduction in deaths among athletes in the 2000s, compared to the previous decade. These results may partly be explained by improved acute preparedness for sudden cardiac arrest (CPR, defibrillation), but as a substantial percentage have preceding risk factors, such as symptoms and ECG-abnormalities, increased cardiac screening and increased general awareness, may also play a role.

Mitral Valve Prolapse, Ventricular Arrhythmias, and Sudden Death

Despite a 2% to 3% prevalence of echocardiographically defined mitral valve prolapse (MVP) in the general population, the actual burden, risk stratification, and treatment of the so-called arrhythmic MVP are unknown. The clinical profile is characterized by a patient, usually female, with mostly bileaflet myxomatous disease, mid-systolic click, repolarization abnormalities in the inferior leads, and complex ventricular arrhythmias with polymorphic/right bundle branch block morphology, without significant regurgitation. Among the various pathophysiologic mechanisms of electrical instability, left ventricular fibrosis in the papillary muscles and inferobasal wall, mitral annulus disjunction, and systolic curling have been recently described by pathological and cardiac magnetic resonance studies in sudden death victims and patients with arrhythmic MVP. In addition, premature ventricular beats arising from the Purkinje tissue as ventricular fibrillation triggers have been documented by electrophysiologic studies in MVP patients with aborted sudden death.

The genesis of malignant ventricular arrhythmias in MVP probably recognizes the combination of the substrate (regional myocardial hypertrophy and fibrosis, Purkinje fibers) and the trigger (mechanical stretch) eliciting premature ventricular beats because of a primary morphofunctional abnormality of the mitral valve annulus.

The main clinical challenge is how to identify patients with arrhythmic MVP (which imaging technique and in which patient) and how to treat them to prevent sudden death. Thus, there is a necessity for prospective multicenter studies focusing on the prognostic role of cardiac magnetic resonance and electrophysiologic studies and on the therapeutic efficacy of targeted catheter ablation and mitral valve surgery in reducing the risk of life-threatening arrhythmias, as well as the role of implantable cardioverter defibrillators for primary prevention.

Can epinephrine therapy be detrimental to patients with hypertrophic cardiomyopathy with hypotension or cardiac arrest? A systematic review

Approximately 10% of sudden cardiac deaths among patients under 35 years of age is owing to hypertrophic cardiomyopathy (HCM)-related cardiac arrest (CA). CA is often associated with pre-arrest or peri-arrest hypotension and is treated by a set of interventions, including the administration of epinephrine. It is debated whether epinephrine increases or decreases survival to discharge following CA. HCM is associated with septal hypertrophy with a dynamic left ventricular outflow tract obstruction and impaired peripheral vasoconstriction in response to α1-adrenergic stimulation, both of which could cause epinephrine to have a different effect than in the general population. This systematic review of the literature aimed to investigate if patients with HCM in CA have a detrimental hemodynamic response to epinephrine. A literature search was performed in October 2016 using Medline (OVID), Embase (Elsevier), and Cochrane Library (Wiley). The initial search generated 2429 articles, of which 22 articles were found to meet inclusion criteria: four physiology studies, 13 case reports of hypotensive HCM patients, and five case reports of HCM patients in CA. The reviewed studies demonstrate that epinephrine effect varies in patients with HCM: in some cases, the expected hypertensive effect was obtained, but in others, a paradoxical hypotensive effect, or no effect, was observed. The probable mechanism of this effect is an increased left ventricular outflow tract obstruction. Other drugs were considered in several of these cases. In summary, the retrieved studies jointly suggest that patients with HCM may respond differently to epinephrine than patients without HCM. The suitability of epinephrine in HCM-associated CA is questionable.

Sudden cardiac death among the young in Sweden from 2000 to 2010: an autopsy-based study

Aims

To study the incidence and aetiology of sudden cardiac death (SCD) in 1- to 35-year-olds in Sweden from 2000 to 2010.

Methods and results

We used the database of the Swedish National Board of Forensic Medicine and the Swedish Cause of Death Registry and identified SCD cases by review of forensic files and death certificates. We identified 552 individuals with SCD in 1- to 35-year-olds; 156 (28%) were women. In 393 (71%), a forensic autopsy had been performed; in 131 (24%), a clinical autopsy had been performed; in 28 (5%) with no autopsy, a cardiac disease was diagnosed before death. The incidence of SCD per 100 000 person-years was 1.3 in 1- to 35-year-olds and 1.8 in 15- to 35-year-olds. In women, the incidence rates yearly decreased during the study period by 11% (95% confidence interval 6.6-14.2). The most common aetiology in 1- to 35-year-olds was sudden arrhythmic death syndrome (31%) and coronary artery disease (15%). In cases with forensic autopsy, death occurred during daily activity (48%), sleep (38%), and physical activity (14%); death was unwitnessed in 60%. Co-morbidity in 15- to 35-year-olds, e.g. psychiatric disorder, obesity, or diabetes, was present in 93/340 (27%) (73 men).

Conclusion

The incidence of SCD among 1- to 35-year-olds in Sweden during 2000-10 was 1.3 per 100 000 person-years (28% women); incidence was decreasing in women. Sudden arrhythmic death syndrome was the most common diagnosis. Co-morbidity such as psychiatric disorders and obesity was common among men.

The highest mortality rates in childhood dilated cardiomyopathy occur during the first year after diagnosis

Aim

The aim of the study was to assess the incidence, mortality and morbidity of dilated cardiomyopathy (DCM) and noncompaction of the left ventricle (LVNC) in Swedish children.

Methods

We reviewed hospital records of all children with dilated cardiomyopathy (DCM) or left ventricular noncompaction cardiomyopathy (LVNC) up to the age of 18 in the healthcare region of western Sweden from 1991 to 2015.

Results

In total, 69 cases (61% males) were identified. The combined incidence of DCM and LVNC was 0.77 (95% CI 0.59‐0.96) per 100 000 person years. Children were divided into six groups, and their outcomes were analysed depending on their aetiology. Idiopathic DCM was reported in 43%, and familial dilated and left ventricular noncompaction aetiology was present in 32%. DCM due to various diseases occurred in 8%. DCM associated with neuromuscular diseases was present in 16%. The overall risk of death or receiving transplants in children with idiopathic and familial DCM was 30% over the study period, and 21% died in the first year after diagnosis.

Conclusion

The combined incidence of DCM and LVNC was similar to previous reports. Most children with idiopathic DCM presented during infancy, and mortality was highest during the first year after diagnosis.

Sudden Cardiac Arrest in Pediatrics

Sudden cardiac arrest (SCA) in the pediatric population is a rare and potentially devastating occurrence. An understanding of the differential diagnosis for the etiology of the cardiac arrest allows for the most effective emergency care and provides the patient with the best possible outcome. Pediatric SCA can occur with or without prodromal symptoms and may occur during exercise or rest. The most common cause is arrhythmia secondary to an underlying channelopathy, cardiomyopathy, or myocarditis. After stabilization, evaluation should include electrocardiogram, chest radiograph, and echocardiogram. Management should focus on decreasing the potential for recurring arrhythmia, maintaining cardiac preload, and thoughtful medication use to prevent exacerbation of the underlying condition. The purpose of this review was to provide the emergency physician with a concise and current review of the incidence, differential diagnosis, and management of pediatric patients presenting with SCA.

Hypertrophic Cardiomyopathy as a Cause of Sudden Cardiac Death in the Young: A Meta-Analysis

BACKGROUND

Sudden cardiac death is often linked with hypertrophic cardiomyopathy in young athletes, but with a divergence of study results. We performed a meta-analysis to compare the prevalence of sudden cardiac deaths associated with hypertrophic cardiomyopathy vs sudden cardiac deaths associated with structurally normal hearts.

METHODS

A structured search of MEDLINE was conducted for studies published from 1990 through 2014. Retrospective cohort studies, patient registries, and autopsy series examining sudden cardiac death etiology in young individuals (age ≤35 years) were included. A random-effects model was applied to generate pooled summary estimates of the percentage of sudden cardiac deaths with structurally normal hearts at postmortem vs those caused by hypertrophic cardiomyopathy. Heterogeneity was assessed using I(2). Subgroup analyses were conducted based on study location, patient age groups, and population types.

RESULTS

Thirty-four studies were included, representing a combined sample of 4605 subjects. The overall pooled percentage of sudden cardiac deaths caused by hypertrophic cardiomyopathy was 10.3% (95% confidence interval [CI], 8.0%-12.6%; I(2) = 87.2%), while sudden cardiac deaths with structurally normal hearts at death were more common (P <.001) at 26.7% (95% CI, 21.0%-32.3%; I(2) = 95.3%). In nonathlete subjects, the pooled percentage of sudden cardiac deaths associated with structurally normal hearts (30.7%; 95% CI, 23.0%-38.4%; I(2) = 96.3%) were significantly more common (P <.001) than sudden cardiac death caused by hypertrophic cardiomyopathy (7.8%; 95% CI, 5.8%-9.9%; I(2) = 80.1%). Among athletes, there was no significant difference between summary estimates of hypertrophic cardiomyopathy and structurally normal hearts (P = .57), except in Europe where structurally normal hearts were more common (P = .01).

CONCLUSIONS

Hypertrophic cardiomyopathy is not a more common finding at death than structurally normal hearts in young subjects with sudden cardiac death. Increased attention should be directed toward identifying causes of death associated with a structurally normal heart in subjects with sudden cardiac death.

Cardiac symptoms before sudden cardiac death caused by hypertrophic cardiomyopathy: a nationwide study among the young in Denmark

AIMS

Hypertrophic cardiomyopathy (HCM) is a frequent cause of sudden cardiac death (SCD) among the young (SCDY). The aim of this study was to characterize symptoms before SCDY due to HCM.

METHODS AND RESULTS

Through review of all death certificates, we identified all SCDs in Danes aged 1-35 years in 2000-2009. Nationwide we included all deaths (n = 8756) and identified 431 autopsied SCDYs. All available records from hospitals and general practitioners were retrieved. To compare symptoms, we included a control groups consisting of traffic accident victims (n = 74). In the 10-year study period, 431 autopsied SCDY cases were reviewed and 38 cases (9%) were included, of which 22 (58%) had morphologic findings diagnostic of HCM and 16 (42%) had findings suggestive, but not diagnostic, of HCM ('possible HCM'). Cardiac symptoms >1 h prior to death were reported in 21 (55%) of cases, and 16 (42%) sought medical attention. One (1%) control had cardiac symptoms before death. Consequently, a significantly higher proportion of cases had cardiac symptoms before death and cases more often sought medical attention than controls (P < 0.001).

CONCLUSION

In conclusion, this nationwide study demonstrates a high frequency of cardiac symptoms prior to death in SCDY cases who died of HCM, as 55% had cardiac symptoms and nearly half of the cases sought medical attention.

Genetic screening in sudden cardiac death in the young can save future lives

Background

Autopsy of sudden cardiac death (SCD) in the young shows a structurally and histologically normal heart in about one third of cases. Sudden death in these cases is believed to be attributed in a high percentage to inherited arrhythmogenic diseases. The purpose of this study was to investigate the value of performing post-mortem genetic analysis for autopsy-negative sudden unexplained death (SUD) in 1 to 35 year olds.

Methods and results

From January 2009 to December 2011, samples from 15 cases suffering SUD were referred to the Department of Clinical Genetics, Umeå University Hospital, Sweden, for molecular genetic evaluation. PCR and bidirectional Sanger sequencing of genes important for long QT syndrome (LQTS), short QT syndrome (SQTS), Brugada syndrome type 1 (BrS1), and catecholaminergic polymorphic ventricular tachycardia (CPVT) (KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, and RYR2) was performed. Multiplex ligation-dependent probe amplification (MLPA) was used to detect large deletions or duplications in the LQTS genes. Six pathogenic sequence variants (four LQTS and two CPVT) were discovered in 15 SUD cases (40 %). Ten first-degree family members were found to be mutation carriers (seven LQTS and three CPVT).

Conclusion

Cardiac ion channel genetic testing in autopsy-negative sudden death victims has a high diagnostic yield, with identification of the disease in 40 % of families. First-degree family members should be offered predictive testing, clinical evaluation, and treatment with the ultimate goal to prevent sudden death.

Sudden adult death syndrome in m.3243A>G-related mitochondrial disease: an unrecognized clinical entity in young, asymptomatic adults

Aims

To provide insight into the mechanism of sudden adult death syndrome (SADS) and to give new clinical guidelines for the cardiac management of patients with the most common mitochondrial DNA mutation, m.3243A>G. These studies were initiated after two young, asymptomatic adults harbouring the m.3243A>G mutation died suddenly and unexpectedly. The m.3243A>G mutation is present in ∼1 in 400 of the population, although the recognized incidence of mitochondrial DNA (mtDNA) disease is ∼1 in 5000.

Methods and results

Pathological studies including histochemistry and molecular genetic analyses performed on various post-mortem samples including cardiac tissues (atrium and ventricles) showed marked respiratory chain deficiency and high levels of the m.3243A>G mutation. Systematic review of cause of death in our m.3243A>G patient cohort showed the person-time incidence rate of sudden adult death is 2.4 per 1000 person-years. A further six cases of sudden death among extended family members have been identified from interrogation of family pedigrees.

Conclusion

Our findings suggest that SADS is an important cause of death in patients with m.3243A>G and likely to be due to widespread respiratory chain deficiency in cardiac muscle. The involvement of asymptomatic relatives highlights the importance of family tracing in patients with m.3243A>G and the need for specific cardiac arrhythmia surveillance in the management of this common genetic disease. In addition, these findings have prompted the derivation of cardiac guidelines specific to patients with m.3243A>G-related mitochondrial disease. Finally, due to the prevalence of this mtDNA point mutation, we recommend inclusion of testing for m.3243A>G mutations in the genetic autopsy of all unexplained cases of SADS.

Symptoms Before Sudden Arrhythmic Death Syndrome: A Nationwide Study Among the Young in Denmark

INTRODUCTION

No studies in an unselected and nationwide setting have characterized the symptoms and medical history of patients with sudden arrhythmic death syndrome (SADS). The aim of this study was to identify and describe the symptoms and medical history of patients before the presentation of SADS.

METHODS AND RESULTS

We have previously identified all of the autopsied sudden cardiac deaths (SCD; n = 314) in Danes aged 1-35 years between 2000 and 2006. After comprehensive pathological and toxicological investigation did not reveal a cause of SCD, 136 of the patients were identified as SADS. The National Patient Registry was utilized to obtain information on all in- and outpatient activity in Danish hospitals. All medical records from hospitals and general practitioners, including death certificates and autopsy reports were reviewed. Before death, 48 (35%) SADS patients had cardiac symptoms; among these, 30 (22%) had contacted the healthcare system. Antecedent symptoms (symptoms >24 hours before death) were present in 34 (25%) patients. Prodromal symptoms (symptoms ≤24 hours before death) were present in 23 (17%) patients. Cardiac symptoms included chest pain (n = 16, 12%), dyspnea (n = 18, 13%), palpitations (n = 2, 1%), presyncope/syncope (n = 23, 17%), and aborted SCD (n = 2, 1%). In addition, seizures (n = 25, 18%) were prevalent. In 61 (45%) SADS cases, no previous medical history were recorded.

CONCLUSION

In this unselected, nationwide study of 136 young SADS patients, 35% had experienced cardiac symptoms before death, most commonly presyncope/syncope, but only one out of five had contacted a healthcare provider with cardiac symptoms.

Update: Causes and symptoms of sudden cardiac death in young athletes

Abstract Sudden cardiac death (SCD) is the leading cause of death during exercise. While initial reports suggested that the most common cause of SCD in young athletes was due to hypertrophic cardiomyopathy (HCM), a critical review of investigations in several populations (athletes, non-athletes, military, national, and international) supports that the most common finding at autopsy of young individuals with SCD is actually a structurally normal heart (SNH). This information is vital for sports medicine clinicians, especially with regard to the pre-participation evaluation (PPE) since cardiac death associated with a SNH is likely attributed to disorders such as arrhythmia or ion channel diseases. This comprehensive review explores the causes of SCD, along with the symptoms preceding death, which ultimately may help refine the PPE and maximize the ability to detect potentially lethal disease prior to competition.

Next-generation sequencing of 34 genes in sudden unexplained death victims in forensics and in patients with channelopathic cardiac diseases

Sudden cardiac death (SCD) is responsible for a large proportion of sudden deaths in young individuals. In forensic medicine, many cases remain unexplained after routine postmortem autopsy and conventional investigations. These cases are called sudden unexplained deaths (SUD). Genetic testing has been suggested useful in forensic medicine, although in general with a significantly lower success rate compared to the clinical setting. The purpose of the study was to estimate the frequency of pathogenic variants in the genes most frequently associated with SCD in SUD cases and compare the frequency to that in patients with inherited cardiac channelopathies. Fifteen forensic SUD cases and 29 patients with channelopathies were investigated. DNA from 34 of the genes most frequently associated with SCD were captured using NimbleGen SeqCap EZ library build and were sequenced with next-generation sequencing (NGS) on an Illumina MiSeq. Likely pathogenic variants were identified in three out of 15 (20%) forensic SUD cases compared to 12 out of 29 (41%) patients with channelopathies. The difference was not statistically significant (p = 0.1). Additionally, two larger deletions of entire exons were identified in two of the patients (7%). The frequency of likely pathogenic variants was >2-fold higher in the clinical setting as compared to SUD cases. However, the demonstration of likely pathogenic variants in three out of 15 forensic SUD cases indicates that NGS investigations will contribute to the clinical investigations. Hence, this has the potential to increase the diagnostic rate significantly in the forensic as well as in the clinical setting.

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.

Sudden cardiac death in the young (5-39 years) in the canton of Vaud, Switzerland

Background

Sudden cardiac death (SCD) among the young is a rare and devastating event, but its exact incidence in many countries remains unknown. An autopsy is recommended in every case because some of the cardiac pathologies may have a genetic origin, which can have an impact on the living family members. The aims of this retrospective study completed in the canton of Vaud, Switzerland were to determine both the incidence of SCD and the autopsy rate for individuals from 5 to 39 years of age.

Methods

The study was conducted from 2000 to 2007 on the basis of official statistics and analysis of the International Classification of Diseases codes for potential SCDs and other deaths that might have been due to cardiac disease.

Results

During the 8 year study period there was an average of 292′546 persons aged 5-39 and there were a total of 1122 deaths, certified as potential SCDs in 3.6% of cases. The calculated incidence is 1.71/100′000 person-years (2.73 for men and 0.69 for women). If all possible cases of SCD (unexplained deaths, drowning, traffic accidents, etc.) are included, the incidence increases to 13.67/100′000 person-years. However, the quality of the officially available data was insufficient to provide an accurate incidence of SCD as well as autopsy rates. The presumed autopsy rate of sudden deaths classified as diseases of the circulatory system is 47.5%. For deaths of unknown cause (11.1% of the deaths), the autopsy was conducted in 13.7% of the cases according to codified data.

Conclusions

The incidence of presumed SCD in the canton of Vaud, Switzerland, is comparable to the data published in the literature for other geographic regions but may be underestimated as it does not take into account other potential SCDs, as unexplained deaths. Increasing the autopsy rate of SCD in the young, better management of information obtained from autopsies as well developing of structured registry could improve the reliability of the statistical data, optimize the diagnostic procedures, and the preventive measures for the family members.

Sudden cardiac death in athletes

A 'paradox of sport' is that in addition to the undisputed health benefits of physical activity, vigorous exertion may transiently increase the risk of acute cardiac events. In general, the risk of sudden cardiac death (SCD) approximately doubles during physical activity and is 2- to 3-fold higher in athletes compared to nonathletes. The incidence of SCD in young athletes is in fact very low, at around 1-3 per 100,000, but attracts much public attention. Variations in incidence figures may be explained by the methodology used for data collection and more importantly by differences between subpopulations of athletes. The incidence of SCD in older (≥ 35 years) athletes is higher and may be expected to rise, as more and older individuals take part in organized sports. SCD is often the first clinical manifestation of a potentially fatal underlying cardiovascular disorder and usually occurs in previously asymptomatic athletes. In the young (<35 years), SCD is mainly due to congenital/inherited cardiac abnormalities, whilst coronary artery disease (CAD) is the most common cause in older athletes. Cardiac screening including family/personal history, physical examination and resting electrocardiogram (ECG) may identify individuals at risk and has the potential to decrease the risk of SCD in young athletes. Screening including the ECG has a high sensitivity for underlying disease in young athletes, but the specificity needs to be improved, whereas the sensitivity of screening without the use of ECG is very low. The screening modality recommended for young athletes is of limited value in older athletes, who should receive individualized screening with cardiac stress testing for patients with high risk of underlying CAD. As cardiovascular screening will never be able to identify all athletes at risk, adequate preparedness is vital in case of a potentially fatal event at the sporting arena/facility. Firstly, we will review the magnitude of the problem of SCD in athletes of different ages, as well as the aetiology. Secondly, we will focus on how to prevent SCD in athletes of all ages, reviewing cardiovascular screening recommendations as well as emergency preparedness and arena safety.

Sudden cardiac death in the young: how can disease recognition and prevention in family members be improved?

Sudden cardiac death (SCD) in young patients (<45 years of age) is a rare event. However, it is particularly tragic as it affects active and often otherwise healthy individuals. Furthermore, SCD may unmask an underlying congenital structural disease or channelopathy. The leading cause of SCD is coronary artery disease; however, the likelihood of an underlying congenital cardiac disease is higher in young individuals. Each SCD should therefore initiate a thorough work-up of an underlying cardiac cause, which should ideally include a molecular autopsy. Familial screening should also be initiated if a physician is years later confronted with a history of SCD in a young patient. The common aim is to prompt identification of affected family members, to include the patient in regular cardiological follow-up and if indicated to initiate prophylactic therapy to prevent further SCD. This current issue on hereditary cardio(myo)pathy will cover the main topics on familial diseases. In addition the role of molecular autopsy and molecular genetic screening is discussed.

The molecular autopsy: an indispensable step following sudden cardiac death in the young?

Annually thousands of sudden deaths involving young individuals (<35 years of age) remain unexplained following a complete medicolegal investigation that includes an autopsy. In fact, epidemiological studies have estimated that over half of sudden deaths involving previously healthy young individuals have no morphological abnormalities identifiable at autopsy. Cardiac channelopathies associated with structurally normal hearts such as long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and Brugada syndrome (BrS), leave no evidence to be found at autopsy, leaving investigators to only speculate that a lethal arrhythmia might lie at the heart of a sudden unexplained death (SUD). In cases of autopsy-negative SUD, continued investigation, through the use of a cardiological and genetic evaluation of first- or second-degree relatives and/or a molecular autopsy, may pinpoint the underlying mechanism attributing to the sudden death and allow for the identification of living family members with the pathogenic substrate that renders them vulnerable to an increased risk for cardiac events, including sudden death.

Thermogenic supplement use does not alter characteristics of sudden death in the young

BACKGROUND

To evaluate supplement use, most notably ephedra, which has been temporally associated with sudden death. Animal models suggest increased myocardial irritability may predispose to primary arrhythmic death.

METHODS

Clinical, pathological, and investigative records from the Office of the Armed Forces Medical Examiner's Cardiovascular Death Registry were reviewed. Forty-eight cases of those with known supplement use were compared to 144 age-, gender-, and socioeconomic-matched controls in a 1:3 case:control manner.

RESULTS

Of the 48 sudden deaths temporally associated with supplement use, the mean age was 34.2 ± 10.0 years and predominantly male (n = 44, 91.7%). The underlying cause of death was fatal atherosclerotic coronary disease in 18 (37.5%), sudden unexplained death in 16 (33.3%), and hypertrophic cardiomyopathy in six (12.5%). Compared with controls, there were no statistically significant differences in adjudicated cause of death. On autopsy, there were no differences in cardiac mass, ventricular wall thickness, or presence of atherosclerosis in those known to be taking identified supplements compared to a control population. In the subject ≥35 years, and known to be taking supplements, there was a significant increase in causality of death as due to sudden unexplained death (relative risk = 5.1 [95% confidence interval, 1.4-18.7]).

CONCLUSIONS

Active surveillance of mortality in an autopsy-derived series of young adults finds atherosclerotic coronary disease and idiopathic sudden death are common etiologies of death when taking supplements, but no cardiac structural or histologic mechanism to suggest different pathologic process than a matched control population.

The molecular autopsy: should the evaluation continue after the funeral?

Sudden cardiac death (SCD) is one of the most common causes of death in developed countries, with most SCDs involving the elderly, and structural heart disease evident at autopsy. Each year, however, thousands of sudden deaths involving individuals younger than 35 years of age remain unexplained after a comprehensive medicolegal investigation that includes an autopsy. In fact, several epidemiologic studies have estimated that at least 3% and up to 53% of sudden deaths involving previously healthy children, adolescents, and young adults show no morphologic abnormalities identifiable at autopsy. Cardiac channelopathies associated with structurally normal hearts such as long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and Brugada syndrome (BrS) yield no evidence to be found at autopsy, leaving coroners, medical examiners, and forensic pathologists only to speculate that a lethal arrhythmia might lie at the heart of a sudden unexplained death (SUD). In cases of autopsy-negative SUD, continued investigation through either a cardiologic and genetic evaluation of first- or second-degree relatives or a molecular autopsy may elucidate the underlying mechanism contributing to the sudden death and allow for identification of living family members with the pathogenic substrate that renders them vulnerable, with an increased risk for cardiac events including syncope, cardiac arrest, and sudden death.

Effectiveness of screening for life-threatening chest pain in children

OBJECTIVE

We sought to determine the incidence of sudden cardiac death among patients discharged from the cardiology clinic with presumed noncardiac chest pain (CP).

METHODS

The records of children >6 years of age who presented to Children's Hospital Boston between January 1, 2000, and December 31, 2009, with a complaint of CP were reviewed for demographic features, clinical characteristics, resource utilization, and presumed diagnosis. Patients were searched for in the US National Death Index and Social Security Death Index.

RESULTS

Data for a total of 3700 patients with CP (median age at evaluation: 13.4 years [range: 7-22.3 years]) were reviewed. The median follow-up period was 4.4 years (range: 0.5-10.4 years), for total of 17 886 patient-years of follow-up data. CP with exertion occurred in 1222 cases (33%), including 15 with associated syncope. A cardiac cause was determined in 37 cases; the remaining 3663 patients (99%) had CP of unknown (n = 1928), musculoskeletal (n = 1345), pulmonary (n = 242), gastrointestinal (n = 108), anxiety-related (n = 34), or drug-related (n = 4) origin. Emergency department visits for CP were documented for 670 patients (18%), and 263 patients (7%) had cardiology follow-up visits related to CP. There were 3 deaths, including 2 suicides and 1 spontaneous retroperitoneal hemorrhage.

CONCLUSION

CP in children is a common complaint and rarely has a cardiac cause. Review of 1 decade of cardiology visits (nearly 18 000 patient years) revealed that no patient discharged from the clinic died as a result of a cardiac condition.

Sudden cardiac death in young athletes

Athletic activity is associated with an increased risk of sudden death for individuals with some congenital or acquired heart disorders. This review considers in particular the causes of death affecting athletes below 35 years of age. In this age group the largest proportion of deaths are caused by diseases with autosomal dominant inheritance such as hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, long QT-syndrome, and Marfan's syndrome. A policy of early cascade-screening of all first-degree relatives of patients with these disorders will therefore detect a substantial number of individuals at risk. A strictly regulated system with preparticipation screening of all athletes following a protocol pioneered in Italy, including school-age children, can also detect cases caused by sporadic new mutations and has been shown to reduce excess mortality among athletes substantially. Recommendations for screening procedure are reviewed. It is concluded that ECG screening ought to be part of preparticipation screening, but using criteria that do not cause too many false positives among athletes. One such suggested protocol will show positive in approximately 5% of screened individuals, among whom many will be screened for these diseases. On this point further research is needed to define what kind of false-positive and false-negative rate these new criteria result in. A less formal system based on cascade-screening of relatives, education of coaches about suspicious symptoms, and preparticipation questionnaires used by athletic clubs, has been associated over time with a sizeable reduction in sudden cardiac deaths among Swedish athletes, and thus appears to be worth implementing even for junior athletes not recommended for formal preparticipation screening. It is strongly argued that in families with autosomal dominant disorders the first screening of children should be carried out no later than 6 to 7 years of age.