Epidemiology and genetics of sudden cardiac death

Long-term stress conditions and out-of-hospital cardiac arrest risk: a nested case-control study

OBJECTIVE

Patients with stress-related disorders and anxiety are at increased risk of developing cardiovascular disease. However, the risk of out-of-hospital cardiac arrest (OHCA) is scarcely investigated. We aimed to establish whether long-term stress (post-traumatic stress disorder, adjustment disorder) or anxiety is associated with OHCA in the general population.

METHODS

We conducted a nested case-control study in a nationwide cohort of individuals between 1 June 2001 and 31 December 2015 in Denmark. Cases were OHCA patients with presumed cardiac causes. Each case was matched by age, sex and date of OHCA with 10 non-OHCA controls from the general population. HRs for OHCA were derived from Cox models after controlling for common OHCA risk factors. Stratified analyses were performed according to sex, age and pre-existing cardiovascular disease.

RESULTS

We included 35 195 OHCAs and 351 950 matched controls (median age 72 years; 66.8% male). Long-term stress conditions were diagnosed in 324 (0.92%) OHCA cases and 1577 (0.45%) non-OHCA controls, and were associated with higher rate of OHCA (HR 1.44, 95% CI 1.27 to 1.64). Anxiety was diagnosed in 299 (0.85%) OHCA cases and 1298 (0.37%) controls, and was associated with increased rate of OHCA (HR 1.56, 95% CI1.37 to 1.79). We found no interaction with sex, age or history of cardiovascular diseases.

CONCLUSION

Patients with stress-related disorders or anxiety have an increased rate of OHCA. This association applies equally to men and women and is independent from the presence of cardiovascular disease. Awareness of the higher risks of OHCA in patients with stress-related disorders and anxiety is important when treating these patients.

Cardiac Magnetic Resonance as an Etiological Diagnosis Tool in Recovered Sudden Cardiac Death or Unstable Ventricular Arrhythmia Patients

BACKGROUND

Cardiac magnetic resonance (CMR) has an increasing diagnostic relevance in survivors of sudden cardiac death (SCD) or unstable ventricular arrhythmia (UVA) in developed countries.

OBJECTIVE

To evaluate retrospectively the additional role of CMR in a developing country where few resources are available, and should be used more effectively.

METHODS

The study included SCD or UVA survivors admitted between 2009 and 2019 at a tertiary academic institution referred to CMR. Demographic, clinical, and laboratory data were collected from the medical records. CMR images and reports were reviewed and their impact on the final etiological diagnosis was determined. A descriptive analysis was performed and p<0.05 established as significant.

RESULTS

Sixty-four patients, 54.9±15.4 years old, and 42 (71.9%) males. Most events (81.3%) were out of the hospital and ventricular tachycardia was the most common rhythm. Cardiovascular medications were previously used by 55 patients, and beta-blockers were the most used medications (37.5%). Electrocardiogram had electrical inactive areas in 21.9% and all of them had fibrosis at CMR. Mean left ventricular ejection fraction (LVEF) was 44±14%, with 60.9% ≤50% and only 29.7% ≤35%. Late gadolinium enhancement was identified in 71.9%, with a transmural pattern in 43.8%. Chagas cardiomyopathy was the most common etiology (28.1%), followed by ischemic cardiomyopathy (17.2%). Among 26 without a previously identified etiology, CMR could define it (15 patients - 57%).

CONCLUSION

In accordance with previous studies in developed countries, CMR was capable of increasing etiological diagnosis and identifying the arrhythmogenic substrate, allowing better care in half of the underdiagnosed patients.

Sudden Cardiac Death: An Update on Commotio Cordis

Sudden cardiac death (SCD) is one of the leading causes of cardiovascular mortality, and it is caused by a diverse array of conditions. Among these is commotio cordis, a relatively infrequent but still significant cause, often seen in young athletes involved in competitive or recreational sports. It is known to be caused by blunt trauma to the chest wall resulting in life-threatening arrhythmia (typically ventricular fibrillation). The current understanding pertains to blunt trauma to the precordium, with an outcome depending on factors such as the type of stimulus, the force of impact, the qualities of the projectile (shape, size, and density), the site of impact, and the timing of impact in relation to the cardiac cycle. In the management of commotio cordis, a history of preceding blunt chest trauma is usually encountered. Imaging is mostly unremarkable except for ECG, which may show malignant ventricular arrhythmias. Treatment is focused on emergent resuscitation with the advanced cardiac life support protocol algorithm, with extensive workup following the return of spontaneous circulation. In the absence of underlying cardiovascular pathologies, implantable cardiac defibrillator insertion is not beneficial, and patients can even resume physical activity if the workup is unremarkable. Proper follow-up is also key in the management and monitoring of re-entrant ventricular arrhythmias, which are amenable to ablative therapy. Prevention of this condition involves protecting the chest wall against blunt trauma, especially with the use of safety balls and chest protectors in certain high-risk sporting activities.  This study aims to elucidate the current epidemiology and clinical management of SCD with a particular focus on a rarely explored etiology, commotio cordis.

From Bumps to Binges: Overview of Deaths Associated with Cocaine in England, Wales and Northern Ireland (2000-2019)

The UK, as the "cocaine capital of Europe," currently accounts for ∼75% of all cocaine-related hospital admissions in Europe. This study aims to analyze the trends in cocaine-related deaths in England, Wales and Northern Ireland over 20 years (2000-2019). Cases reported to the National Programme on Substance Abuse Deaths (NPSAD) occurring between 2000 and 2019 where cocaine was detected at post-mortem (PM) were extracted for analysis. A total of 5,339 cases were retrieved, with an increase in the rate of reporting over time. Cocaine was deemed a cause of death and quantified in PM blood samples along with its major metabolite benzoylecgonine in 685 cases. Of these 685 cases, 25% (n = 170/685) occurred following acute use, 22% (n = 154/685) following chronic/binge use, 40% (n = 271/685) in combination with morphine, 4% (n = 29/685) in drug packer/swallower circumstances and 9% (n = 61/685) in a suicide context. Cardiac complications were evident in 22% of cases (n = 154/685). The average concentration of cocaine detected in cardiac cases (900 ng/mL) was considerably lower than that detected in cases where acute (19,100 ng/mL) or chronic/binge (6,200 ng/mL) dosing was evident. This is the first cocaine-related mortality study in these geographical areas. Deaths following cocaine use continue to rise despite its Class A drug listing in the UK. While underlying and external risk factors including polydrug use, cardiac complications and mental health can all contribute to the incidence of fatal drug toxicity following cocaine use, this study demonstrates that the risk of a cocaine overdose cannot be attributed to a specific blood concentration range.

Incidence of Cardiac Arrest During Sports Among Women in the European Union

BACKGROUND

Women represent a growing proportion of sports participants. Still, few original data regarding sudden cardiac arrest during sports (Sr-SCA) in women are available.

OBJECTIVES

The authors sought to assess the incidence, characteristics, and outcomes of women presenting with Sr-SCA.

METHODS

Data were analyzed from 3 population-based European registries (ESCAPE-NET 2020 Horizon Program) that prospectively and exhaustively collect every case of SCA: SDEC (Paris-Sudden Death Expertise Center), ARREST (AmsteRdam REsuscitation Studies), and SRCR (Swedish Register for Cardiopulmonary Resuscitation). Sr-SCA was defined as SCA during or ≤1 hour after cessation of sports activity.

RESULTS

Of 34,826 SCA between 2006 and 2017, 760 Sr-SCA (2.2%) were identified, including 54 in women. The average annual incidence of Sr-SCA in women in the 3 registries ranged from 0.10 per million (95% CI: 0.01-0.71 per million) to 0.38 per million (95% CI: 0.14-1.04 per million). Overall, the average annual incidence rate of Sr-SCA in women was 0.19 per million (95% CI: 0.14-0.24 per million), >10-fold lower compared with men (2.63 per million [95% CI: 2.45-2.83 per million]; P < 0.0001). When extrapolating to the total European population and accounting for age and sex, this yields 98 cases per year (95% CI: 72-123 cases per year) in women and 1,350 cases per year (95% CI: 1,256-1,451 cases per year) in men. Subject characteristics and circumstances of occurrence were similar in women vs men. Bystander response, time to defibrillation, and survival rate at hospital admission (58.8% vs 58.5%; P = 0.99) and 30 days did not differ significantly between women and men.

CONCLUSIONS

These findings emphasize the dramatically lower risk of Sr-SCA in women compared with men, despite similar subject characteristics. This should be considered in designing preparticipation screening strategies in the future.

Forensic identification of sudden cardiac death: a new approach combining metabolomics and machine learning

The determination of sudden cardiac death (SCD) is one of the difficult tasks in the forensic practice, especially in the absence of specific morphological changes in the autopsies and histological investigations. In this study, we combined the metabolic characteristics from corpse specimens of cardiac blood and cardiac muscle to predict SCD. Firstly, ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UPLC-HRMS)-based untargeted metabolomics was applied to obtain the metabolomic profiles of the specimens, and 18 and 16 differential metabolites were identified in the cardiac blood and cardiac muscle from the corpses of those who died of SCD, respectively. Several possible metabolic pathways were proposed to explain these metabolic alterations, including the metabolism of energy, amino acids, and lipids. Then, we validated the capability of these combinations of differential metabolites to distinguish between SCD and non-SCD through multiple machine learning algorithms. The results showed that stacking model integrated differential metabolites featured from the specimens showed the best performance with 92.31% accuracy, 93.08% precision, 92.31% recall, 91.96% F1 score, and 0.92 AUC. Our results revealed that the SCD metabolic signature identified by metabolomics and ensemble learning in cardiac blood and cardiac muscle has potential in SCD post-mortem diagnosis and metabolic mechanism investigations.

Type 2 diabetes mellitus and higher rate of complete atrioventricular block: a Danish Nationwide Registry

AIMS

The present study aimed to determine the association between Type 2 diabetes mellitus (T2DM) and third-degree (complete) atrioventricular block.

METHODS AND RESULTS

This nationwide nested case-control study included patients older than 18 years, diagnosed with third-degree atrioventricular block between 1 July 1995 and 31 December 2018. Data on medication, comorbidity, and outcomes were collected from Danish registries. Five controls, from the risk set of each case of third-degree atrioventricular block, were matched on age and sex to fit a Cox regression model with time-dependent exposure and time-dependent covariates. Subgroup analysis was conducted with Cox regression models for each subgroup. We located 25 995 cases with third-degree atrioventricular block that were matched with 130 004 controls. The mean age was 76 years and 62% were male. Cases had more T2DM (21% vs. 11%), hypertension (69% vs. 50%), atrial fibrillation (25% vs. 10%), heart failure (20% vs. 6.3%), and myocardial infarction (19% vs. 9.2%), compared with the control group. In Cox regression analysis, adjusting for comorbidities and atrioventricular nodal blocking agents, T2DM was significantly associated with third-degree atrioventricular block (hazard ratio: 1.63, 95% confidence interval: 1.57-1.69). The association remained in several subgroup analyses of diseases also suspected to be associated with third-degree atrioventricular block. There was a significant interaction with comorbidities of interest including hypertension, atrial fibrillation, heart failure, and myocardial infarction.

CONCLUSION

In this nationwide study, T2DM was associated with a higher rate of third-degree atrioventricular block compared with matched controls. The association remained independent of atrioventricular nodal blocking agents and other comorbidities known to be associated with third-degree atrioventricular block.

Molecular autopsy: Twenty years of post-mortem diagnosis in sudden cardiac death

In the forensic medicine field, molecular autopsy is the post-mortem genetic analysis performed to attempt to unravel the cause of decease in cases remaining unexplained after a comprehensive forensic autopsy. This negative autopsy, classified as negative or non-conclusive, usually occurs in young population. In these cases, in which the cause of death is unascertained after a thorough autopsy, an underlying inherited arrhythmogenic syndrome is the main suspected cause of death. Next-generation sequencing allows a rapid and cost-effectives genetic analysis, identifying a rare variant classified as potentially pathogenic in up to 25% of sudden death cases in young population. The first symptom of an inherited arrhythmogenic disease may be a malignant arrhythmia, and even sudden death. Early identification of a pathogenic genetic alteration associated with an inherited arrhythmogenic syndrome may help to adopt preventive personalized measures to reduce risk of malignant arrhythmias and sudden death in the victim's relatives, at risk despite being asymptomatic. The current main challenge is a proper genetic interpretation of variants identified and useful clinical translation. The implications of this personalized translational medicine are multifaceted, requiring the dedication of a specialized team, including forensic scientists, pathologists, cardiologists, pediatric cardiologists, and geneticists.

Risk of out-of-hospital cardiac arrest in patients with sarcoidosis: a Danish nationwide nested case-control study

ObjectiveSarcoidosis is over-represented among victims of cardiac arrest. We aimed to establish whether sarcoidosis is associated with out-of-hospital cardiac arrest (OHCA) in the general population.MethodsWe conducted a nested case-control study in a nationwide cohort of individuals between 1 June 2001 and 31 December 2015 in Denmark. OHCA cases from presumed cardiac causes were matched 1:10 by sex and age on OHCA date with non-OHCA controls from the general population. The association between sarcoidosis and OHCA was assessed using Cox regression by calculating HR and 95% CIs. Models were adjusted for cardiovascular disease. Finally, stratified analyses were performed according to sex, heart failure and ischaemic heart disease. RESULTS: We identified 35 195 OHCA cases and 351 950 matched controls without OHCA (median age 72 years and 66.8% male). Patients with sarcoidosis had higher rate of OHCA compared with the general population after adjustments for common OHCA risk factors (HR 1.51, 95% CI 1.19 to 1.92). This increased OHCA rate occurred in women (HR 2.11, 95% CI 1.42 to 3.12) but not in men (HR 1.27, 95% CI 0.93 to 1.72; p value interaction=0.033), and was larger in patients with than without heart failure (HR_{heart failure}: 2.59, 95% CI 1.42 to 4.73; HR_{no heart failure}: 1.33, 95% CI 1.01 to 1.74; p value interaction: 0.007). The HR associated with sarcoidosis did not vary by the presence of ischaemic heart disease. CONCLUSION: Patients with sarcoidosis have a higher OHCA rate than the general population. This increased OHCA rate occurred in women but not in men, and was larger in patients with than without heart failure.

Standing genetic variation affects phenotypic heterogeneity in an SCN5A-mutation founder population with excess sudden cardiac death

BACKGROUND

The Worm Study, ascertained from a multigeneration pedigree segregating a single amino acid deletion in SCN5A (c.4850_4852delTCT, p.(Phe1617del), rs749697698), is characterized by substantial phenotypic heterogeneity and overlap of sudden cardiac death, long-QT syndrome, cardiac conduction disease, Brugada syndrome, and isorhythmic atrioventricular dissociation. Linkage analysis for a synthetic trait derived from these phenotypes identified a single peak (logarithm of the odds [LOD] = 4.52) at the SCN5A/SCN10A/SCN11A locus on chromosome 3.

OBJECTIVE

This study explored the role of additional genetic variation in the chromosome 3 locus as a source of phenotypic heterogeneity in the Worm Study population.

METHODS

Genotypes underlying the linkage peak (n = 70) were characterized using microarrays. Haplotypes were determined using family-aware phasing and a population-specific reference panel. Variants with minor allele frequencies >0.10 were tested for association with cardiac conduction disease and isorhythmic dissociation using LAMP and logistic regression.

RESULTS

Only 1 haplotype carried the p.Phe1617del/rs749697698 deletion, suggesting relatively recent development (∼18 generations); this haplotype contained 5 other missense variants spanning SCN5A/SCN10A/SCN11A. Noncarrier haplotypes (n = 74) ranged in frequency from 0.5% to 5%. Although no variants were associated with cardiac conduction disease, a homozygous missense variant in SCN10A was associated with isorhythmic dissociation after correction for multiple comparisons (odds ratio 11.23; 95% confidence interval 2.76-23.39; P = 1.2 × 10^-4). This variant (rs12632942) was previously associated with PR interval.

CONCLUSION

Our data suggest that other variants, alongside a pathogenic mutation, are associated with phenotypic heterogeneity. Single-mutation screening may be insufficient to predict electrical heart disease in patients and family members. In the Worm Study population, segregating a pathogenic SCN5A mutation, compound variation in the SCN5A/SCN10A/SCN11A locus determines arrhythmic outcome.

Sudden Cardiac Death in Athletes: Facts and Fallacies

The benefits of exercise for cardiovascular and general health are many. However, sudden cardiac death (SCD) may occur in apparently healthy athletes who perform at the highest levels. A diverse spectrum of diseases is implicated in SCD in athletes, and while atherosclerotic coronary artery disease predominates in individuals of >35 years of age, primary cardiomyopathies and ion channelopathies are prevalent in young individuals. Prevention of SCD in athletes relies on the implementation of health policies aimed at the early identification of arrhythmogenic diseases (such as cardiac screening) and successful resuscitation (such as widespread utilization of automatic external defibrillators and training members of the public on cardiopulmonary resuscitation). This review will focus on the epidemiology and aetiologies of SCD in athletes, and examine fallacies in the approach to this controversial field. Furthermore, potential strategies to prevent these tragic events will be discussed, analysing current practice, gaps in knowledge and future directions.

ST-segment elevation predicts the occurrence of malignant ventricular arrhythmia events in patients with acute ST-segment elevation myocardial infarction

BACKGROUND

ST-segment elevation (STE) represents a repolarization dispersion marker underlying arrhythmogenesis in ST-segment elevation myocardial infarction (STEMI); however, its value for predicting malignant ventricular arrhythmia events (MVAEs) remains uncertain.

METHODS

In total, 285 patients with STEMI and those with or without MVAEs who presented within 6 h of symptom onset were enrolled. The relationships between STE and clinical characteristics of MVAEs (defined as ventricular tachycardia or ventricular fibrillation) were analyzed using t-test, chi-square test, binary multivariate logistic regression, and receiver operating characteristic curve analysis.

RESULTS

Patients with STEMI and MVAEs had a shorter time from symptom onset to balloon time (p = 0.0285) and greater STE (p < 0.01) than those without MVAEs. The symptom-to-balloon time, age, and STE were associated with MVAEs after stepwise regression analysis in all cases. Only STE was significantly associated with the occurrence of MVAEs (all, p < 0.01). The area under the curve (AUC) of STE for predicting MVAEs was 0.905, and the cut-off value was 4.5 mV. When only infarct-related arteries were included in the analysis, the AUC of the left anterior descending artery was 0.925 with a cut-off value of 4.5 mV, that of the right coronary artery was 0.915 with a cut-off value of 4.5 mV, and that of the left circumflex artery was 0.929 with a cut-off value of 4.0 mV.

CONCLUSIONS

In patients with STEMI presenting within 6 h of symptom onset, age, symptom-to-balloon time, and STE were the main predictors for MVAEs. However, among these, STE was the strongest predictor for MVAEs and was an index for repolarization dispersion of cardiomyocytes in infarcted and non-infarcted areas.

Waterpipe Use and Its Cardiovascular Effects: A Systematic Review and Meta-Analysis of Case-Control, Cross-Sectional, and Non-Randomized Studies

Approximately 100 million people globally smoke cigarettes, making it a significant and quickly spreading global tobacco epidemic. Substance use disorders are frequently evaluated by non-randomized studies. Tobacco use and its impacts on the cardiovascular system were the subjects of a comprehensive search across five electronic databases: Cochrane, MEDLINE, Scopus, Embase, and PubMed. The findings demonstrated that waterpipe smokers in comparison to non-smokers have immediate elevations in heart rate and blood pressure, lower levels of high-density lipoprotein, higher levels of low-density lipoprotein, higher levels of triglycerides, higher levels of fasting blood glucose, and a higher heart rate. Users of waterpipes and cigarettes had similar average heart rates, blood pressure, and lipid levels, with the exception that waterpipe smokers had greater total cholesterol. Smoking a waterpipe has significant negative effects on the cardiovascular system comparable to cigarette smoking, and non-randomized studies proved to yield substantial evidence related to its cardiovascular effects. Such study designs can be used to evaluate substance use and its cardiovascular impact.

Alcohol and Arrhythmias

The association between alcohol consumption and abnormalities of heart rate and rhythm has long been recognized. Significant attention has focused on the risk of atrial fibrillation (AF) and sudden cardiac death (SCD) with excessive alcohol intake. Recent studies have advanced our understanding of these relationships and provided additional insights into potentially arrhythmogenic mechanisms. However, considerable uncertainty remains, such as the level of consumption at which harm begins and whether alcohol plays a role in other arrhythmias. This review characterizes the spectrum of conduction abnormalities and heart rhythm disorders in relation to alcohol consumption. In addition, it discusses the latest epidemiologic and experimental evidence, the potential importance of beverage type and constituent ingredients, and conflicting information on drink definitions, thresholds, and recommendations.

Androgen receptor (CAG)n repeat polymorphism contributes to risk of sudden cardiac death originated from coronary artery disease with sex discrepancy

Sudden cardiac death (SCD) is the leading cause of natural death worldwide which is responsible for almost half of all heart disease deaths, making it a substantial public health problem. Previous epidemiological studies from different countries have demonstrated the significant SCD incident difference rate between males and females. Besides environmental and social effects, differential genetic architecture also underlines the SCD incidence discrepancy. To this end, the functional (CAG)_n repeat polymorphism within Androgen Receptor (AR) gene was analyzed to evaluate its associations with SCD originated from coronary artery disease (SCD-CAD) susceptibility in Chinese populations using 182 SCD-CAD cases and 564 healthy controls. At allelic level, the (CAG)₂₆ allele conferred a lower SCD-CAD risk in males (adjusted odds ratio [OR] = 0.428; 95% confidence interval [CI] = 0.254, 0.915; P = 0.023). On the contrary, the (CAG)₂₆ allele was reversely associated with a higher SCD-CAD risk in females (OR = 2.581; 95% CI = 0.944, 7.056; P = 0.057). Further cutoff strategy analysis revealed that those male subjects carrying shorter allele (≤26 repeats) had significantly lower SCD-CAD risk (OR = 0.343; 95% CI = 0.221, 0.531; P = 8.1653e^-7). Additionally, an allele-dependent SCD risk tendency was observed in male subjects. Specifically, compared with males carrying allele longer than 26 repeats, the SCD-CAD risk (OR value) for male subjects carrying shorter alleles (from 25 to 21) gradually increased from 0.437 to 0.533, indicating the (CAG)₂₆ allele of the repeat polymorphism may be the watershed in male SCD etiology. Lastly, the length variations associated with multiple phenotypes were also summarized. Collectively, our results revealed for the first time that the (CAG)_n repeat polymorphism within the AR gene was associated with SCD-CAD risk in Chinese populations with sex discrepancy, proposing a new candidate genetic marker for molecular diagnosis of SCD-CAD. Furthermore, a sex-dependent SCD-CAD risk stratification and prevention approach was encouraged. Further studies with more female samples were warranted to validate our findings.

Age and the Risk of Ventricular Tachyarrhythmia in Patients With an Implantable Cardioverter-Defibrillator

BACKGROUND

The benefit of implantable cardioverter-defibrillators (ICDs) in elderly patients is controversial.

OBJECTIVES

The aims of this study were to evaluate the risk for ventricular tachyarrhythmia (VTA) and ICD shocks by age groups and to assess the competing risk for VTA and death without prior VTA.

METHODS

The study included 5,170 primary prevention ICD recipients enrolled in 5 landmark ICD trials (MADIT [Multicenter Automatic Defibrillator Implantation Trial] II, MADIT-Risk, MADIT-CRT [MADIT Cardiac Resynchronization Therapy], MADIT-RIT [MADIT Reduce Inappropriate Therapy], and RAID [Ranolazine in High-Risk Patients With Implanted Cardioverter-Defibrillator]). Fine and Gray regression analysis was used to evaluate the risk for fast VTA (ventricular tachycardia ≥200 beats/min or ventricular fibrillation) vs death without prior fast VTA in 3 prespecified age groups: <65, 65 to <75, and ≥75 years.

RESULTS

The cumulative incidence of fast VTA at 3 years was similar for patients <65 years of age and those 65 to <75 years of age (17% vs 15%) and was lowest among patients ≥75 years of age (10%) (P < 0.001). Multivariate Fine and Gray analysis showed a 40% lower risk for fast VTA in patients ≥75 years of age (HR: 0.60; 95% CI: 0.46-0.78; P < 0.001) compared with patients <65 years of age. In patients ≥75 years of age, a risk reversal was observed whereby the risk for death without prior fast VTA exceeded the risk for developing fast VTA. A history of nonsustained ventricular tachycardia, male sex, and the presence of nonischemic cardiomyopathy were identified as predictors of fast VTA in patients ≥75 years of age.

CONCLUSIONS

Patients ≥75 years of age have a significantly lower risk for VTA and ICD shocks compared with younger patients. Aging is associated with a higher risk for death compared with the risk for fast VTA, the reverse of what is seen in younger patients.

Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals

Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. Although recent advances in cell-based models, including human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM), are contributing to our understanding of electrophysiology and arrhythmia mechanisms, preclinical animal studies of cardiovascular disease remain a mainstay. Over the past several decades, animal models of cardiovascular disease have advanced our understanding of pathological remodeling, arrhythmia mechanisms, and drug effects and have led to major improvements in pacing and defibrillation therapies. There exist a variety of methodological approaches for the assessment of cardiac electrophysiology and a plethora of parameters may be assessed with each approach. This guidelines article will provide an overview of the strengths and limitations of several common techniques used to assess electrophysiology and arrhythmia mechanisms at the whole animal, whole heart, and tissue level with a focus on small animal models. We also define key electrophysiological parameters that should be assessed, along with their physiological underpinnings, and the best methods with which to assess these parameters.

Ventricular arrhythmias in acute myocardial ischaemia-Focus on the ageing and sex

Annually, approximately 17 million people die from cardiovascular diseases worldwide, half of them suddenly. The most common direct cause of sudden cardiac death is ventricular arrhythmia triggered by an acute coronary syndrome (ACS). The study summarizes the knowledge of the mechanisms of arrhythmia onset during ACS in humans and in animal models and factors that may influence the susceptibility to life-threatening arrhythmias during ACS with particular focus on the age and sex. The real impact of age and sex on the arrhythmic susceptibility within the setting of acute ischaemia is masked by the fact that ACSs result from coronary artery disease appearing with age much earlier among men than among women. However, results of researches show that in ageing process changes with potential pro-arrhythmic significance, such as increased fibrosis, cardiomyocyte hypertrophy, decrease number of gap junction channels, disturbances of the intracellular Ca²⁺ signalling or changes in electrophysiological parameters, occur independently of the development of cardiovascular diseases and are more severe in male individuals. A review of the literature also indicates a marked paucity of research in this area in female and elderly individuals. Greater awareness of sex differences in the aging process could help in the development of personalized prevention methods targeting potential pro-arrhythmic factors in patients of both sexes to reduce mortality during the acute phase of myocardial infarction. This is especially important in an era of aging populations in which women will predominate due to their longer lifespan.

Psychological Distress After Sudden Cardiac Arrest and Its Impact on Recovery

PURPOSE OF REVIEW

To summarize the prevalence, correlates, and health consequences of poor mental health in the increasingly sizable population of survivors of Sudden cardiac arrest (CA) and to describe current intervention research in this area.

RECENT FINDINGS

After CA many patients report high psychological distress, including depression, generalized anxiety, and posttraumatic stress. Emerging evidence suggests that distressed patients' attention may narrow such that anxious awareness of afferent cardiac signals e.g., changes in heart rate or blood pressure, becomes predominant and a cause for concerned, constant monitoring. This cardiac-specific anxiety followed by behavioral avoidance and physiological hyperreactivity may increase patients' already high risk of secondary cardiovascular disease and undermine their health-related quality of life (HRQoL). Unlike other cardiovascular diseases, no clinical practice guidelines exist for assessing or treating psychological sequelae of CA. Future research should identify modifiable psychological targets to reduce secondary cardiovascular disease risk and improve HRQoL.

In-hospital arrhythmic burden reduction in diabetic patients with acute myocardial infarction treated with SGLT2-inhibitors: Insights from the SGLT2-I AMI PROTECT study

Background

Sodium-glucose co-transporter 2 inhibitors (SGLT2-i) have shown significant cardiovascular benefits in patients with and without type 2 diabetes mellitus (T2DM). They have also gained interest for their potential anti-arrhythmic role and their ability to reduce the occurrence of atrial fibrillation (AF) and ventricular arrhythmias (VAs) in T2DM and heart failure patients.

Objectives

To investigate in-hospital new-onset cardiac arrhythmias in a cohort of T2DM patients presenting with acute myocardial infarction (AMI) treated with SGLT2-i vs. other oral anti-diabetic agents (non-SGLT2-i users).

Methods

Patients from the SGLT2-I AMI PROTECT registry (NCT05261867) were stratified according to the use of SGLT2-i before admission for AMI, divided into SGLT2-i users vs. non-SGLT2-i users. In-hospital outcomes included the occurrence of in-hospital new-onset cardiac arrhythmias (NOCAs), defined as a composite of new-onset AF and sustained new-onset ventricular tachycardia (VT) and/or ventricular fibrillation (VF) during hospitalization.

Results

The study population comprised 646 AMI patients categorized into SGLT2-i users (111 patients) and non-SGLT2-i users (535 patients). SGLT2-i users had a lower rate of NOCAs compared with non-SGLT2-i users (6.3 vs. 15.7%, p = 0.010). Moreover, SGLT2-i was associated with a lower rate of AF and VT/VF considered individually (p = 0.032). In the multivariate logistic regression model, after adjusting for all confounding factors, the use of SGLT2-i was identified as an independent predictor of the lower occurrence of NOCAs (OR = 0.35; 95%CI 0.14-0.86; p = 0.022). At multinomial logistic regression, after adjusting for potential confounders, SGLT2-i therapy remained an independent predictor of VT/VF occurrence (OR = 0.20; 95%CI 0.04-0.97; p = 0.046) but not of AF occurrence.

Conclusions

In T2DM patients, the use of SGLT2-i was associated with a lower risk of new-onset arrhythmic events during hospitalization for AMI. In particular, the primary effect was expressed in the reduction of VAs. These findings emphasize the cardioprotective effects of SGLT2-i in the setting of AMI beyond glycemic control.

Trial registration

Data are part of the observational international registry: SGLT2-I AMI PROTECT. ClinicalTrials.gov, identifier: NCT05261867.

Sex-Based Differences in 30-Day Readmissions After Cardiac Arrest: Analysis of the Nationwide Readmissions Database

Background There are limited data on the sex-based differences in the outcome of readmission after cardiac arrest. Methods and Results Using the Nationwide Readmissions Database, we analyzed patients hospitalized with cardiac arrest between 2010 and 2015. Based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, we identified comorbidities, therapeutic interventions, and outcomes. Multivariable logistic regression was performed to assess the independent association between sex and outcomes. Of 835 894 patients, 44.4% (n=371 455) were women, of whom 80.7% presented with pulseless electrical activity (PEA)/asystole. Women primarily presented with PEA/asystole (80.7% versus 72.4%) and had a greater comorbidity burden than men, as assessed using the Elixhauser Comorbidity Score. Thirty-day readmission rates were higher in women than men in both PEA/asystole (20.8% versus 19.6%) and ventricular tachycardia/ventricular fibrillation arrests (19.4% versus 17.1%). Among ventricular tachycardia/ventricular fibrillation arrest survivors, women were more likely than men to be readmitted because of noncardiac causes, predominantly infectious, respiratory, and gastrointestinal illnesses. Among PEA/asystole survivors, women were at higher risk for all-cause (adjusted odds ratio [aOR], 1.07; [95% CI, 1.03-1.11]), cardiac-cause (aOR, 1.15; [95% CI, 1.06-1.25]), and noncardiac-cause (aOR, 1.13; [95% CI, 1.04-1.22]) readmission. During the index hospitalization, women were less likely than men to receive therapeutic procedures, including coronary angiography and targeted therapeutic management. While the crude case fatality rate was higher in women, in both ventricular tachycardia/ventricular fibrillation (51.8% versus 47.4%) and PEA/asystole (69.3% versus 68.5%) arrests, sex was not independently associated with increased crude case fatality after adjusting for differences in baseline characteristics. Conclusions Women are at increased risk of readmission following cardiac arrest, independent of comorbidities and therapeutic interventions.

Imaging for risk stratification of sudden cardiac death

Sudden cardiac death (SCD) can be effectively prevented with the use of implantable cardioverter-defibrillator (ICD). Current guidelines advocate an ICD for primary prevention in the presence of an left ventricular ejection fraction (LVEF) ≤ 35%. The majority of individuals that experience SCD, however, have an LVEF > 35%. Multimodality cardiac imaging has the ability to visualize the three factors responsible for arrhythmia-mediated SCD, namely substrate, trigger and modulator. Advances in cardiac imaging techniques have allowed improved SCD risk stratification, especially in the group of patients with an LVEF > 35%. However, clinical integration of cardiac imaging for SCD risk stratification will require more comparative data between modalities and parameters, as well as evidence of an impact on outcomes. The current review represents an update on the use of multimodality imaging techniques for SCD risk stratification.

Polygenic Risk Score Predicts Sudden Death in Patients With Coronary Disease and Preserved Systolic Function

BACKGROUND

A familial predisposition to sudden and/or arrhythmic death (SAD) in the setting of coronary artery disease (CAD) exists; however, the genetic basis is poorly understood.

OBJECTIVES

The purpose of this study was to determine whether a genome-wide polygenic score for coronary artery disease (GPSCAD) might have utility in SAD risk stratification in CAD patients without severe systolic dysfunction.

METHODS

A previously validated GPSCAD was generated utilizing genome-wide genotyping in 4,698 PRE-DETERMINE participants of European ancestry with CAD and left ventricular ejection fraction >30%-35%. The population was dichotomized according to top GPSCAD decile as defined by the general population, and absolute, proportional, and relative risks for SAD and non-SAD were estimated using competing risk analyses.

RESULTS

Over a median follow-up of 8.0 years, participants in the top GPSCAD decile were at elevated absolute SAD risk (8.0%; 95% CI: 5.1%-12.4% vs 4.8%; 95% CI: 3.3%-7.0%; P = 0.005) and proportional SAD risk (29% vs 16%; P = 0.0003) compared with the remainder. After controlling for left ventricular ejection fraction, clinical factors, and electrocardiogram parameters, the top GPSCAD decile was associated with SAD (subdistribution HR: 1.77; 95% CI: 1.23-2.54; P = 0.002) but not non-SAD (subdistribution HR: 1.00; 95% CI: 0.80-1.25; P = 0.98) (P for Δ = 0.003). The addition of the top GPSCAD decile to the multivariable model significantly improved net reclassification indexes (NRIs) (continuous NRI: 14.0%; P = 0.024; and categorical NRI: 6.6%; P = 0.005) but not the C-index (difference in C-index: 0.007; P = 0.143).

CONCLUSIONS

Among CAD patients without severe systolic dysfunction, high GPSCAD specifically predicted SAD and enriched for both absolute and proportional SAD risk, identifying a population who might benefit from defibrillator therapy.

Use of sodium-glucose cotransporter-2 inhibitors and the risk for sudden cardiac arrest and for all-cause death in patients with type 2 diabetes mellitus

AIMS

Sodium-glucose cotransporter-2 inhibitors (SGLT-2is) are antidiabetic agents that can have direct cardiac effects by impacting on cardiac ion transport mechanisms that control cardiac electrophysiology. We studied the association between SGLT-2i use and all-cause mortality and the risk of sudden cardiac arrest (SCA) in patients with type 2 diabetes.

METHODS

Using data from the UK Clinical Practice Research Datalink, a cohort study among patients initiating a new antidiabetic drug class on or after January 2013 through September 2020 was conducted. A Cox regression with time-dependent covariates was performed to estimate the hazard ratios (HRs) of SCA and all-cause mortality comparing SGLT-2is with other second- to third-line antidiabetic drugs. Stratified analyses were performed according to sex, diabetes duration (<5 or ≥5 years), and the presence of cardiovascular disease.

RESULTS

A total of 152 591 patients were included. Use of SGLT-2i was associated with a reduced HR of SCA when compared with other second- to third-line antidiabetic drugs after adjustment for common SCA risk factors, although this association marginally failed to reach statistical significance [HR: 0.62, 95% confidence interval (95% CI): 0.38-1.01]. The HR of all-cause mortality associated with SGLT-2i use when compared with other second- to third-line antidiabetics was 0.43 (95% CI: 0.39-0.48) and did not vary by sex, diabetes duration, or the presence of cardiovascular disease. SGLT-2i use remained associated with lower all-cause mortality in patients without concomitant insulin use (HR: 0.56, 95% CI: 0.50-0.63).

CONCLUSION

SGLT-2i use was associated with reduced all-cause mortality in patients with type 2 diabetes. The association between use of SGLT-2i and reduced risk of SCA was not statistically significant.

Ischaemic electrocardiogram patterns and its association with survival in out-of-hospital cardiac arrest patients without ST-segment elevation myocardial infarction: a COACT trials’ post-hoc subgroup analysis

Aims

ST-depression and T-wave inversion are frequently present on the post-resuscitation electrocardiogram (ECG). However, the prognostic value of ischaemic ECG patterns is unknown.

Methods and results

In this post-hoc subgroup analysis of the Coronary Angiography after Cardiac arrest (COACT) trial, the first in-hospital post-resuscitation ECG in out-of-hospital cardiac arrest patients with a shockable rhythm was analysed for ischaemic ECG patterns. Ischaemia was defined as ST-depression of ≥0.1 mV, T-wave inversion in ≥2 contiguous leads, or both. The primary endpoint was 90-day survival. Secondary endpoints were rate of acute unstable lesions, levels of serum troponin-T, and left ventricular function. Of the 510 out-of-hospital cardiac arrest patients, 340 (66.7%) patients had ischaemic ECG patterns. Patients with ischaemic ECG patterns had a worse 90-day survival compared with those without [hazard ratio 1.51; 95% confidence interval (CI) 1.08–2.12; P = 0.02]. A higher sum of ST-depression was associated with lower survival (log-rank = 0.01). The rate of acute unstable lesions (14.5 vs. 15.8%; odds ratio 0.90; 95% CI 0.51–1.59) did not differ between the groups. In patients with ischaemic ECG patterns, maximum levels of serum troponin-T (μg/L) were higher [0.595 (interquartile range 0.243–1.430) vs. 0.359 (0.159–0.845); ratio of geometric means 1.58; 1.13–2.20] and left ventricular function (%) was worse (44.7 ± 12.5 vs. 49.9 ± 13.3; mean difference −5.13; 95% CI −8.84 to −1.42). Adjusted for age and time to return of spontaneous circulation, ischaemic ECG patterns were no longer associated with survival.

Conclusion

Post-arrest ischaemic ECG patterns were associated with worse 90-day survival. A higher sum of ST-depression was associated with lower survival. Adjusted for age and time to return of spontaneous circulation, ischaemic ECG patterns were no longer associated with survival.

Cardiorespiratory Fitness, Inflammation, and Risk of Sudden Cardiac Death in Middle-Aged Men

Inflammation and cardiorespiratory fitness (CRF) are each independently related to the risk of sudden cardiac death (SCD). The interplay between CRF, inflammation and SCD is not well understood. We aimed to study the separate and joint associations of inflammation (high-sensitivity C-reactive protein [hsCRP]) and CRF with SCD risk in a cohort of Caucasian men. In 1,749 men aged 42 to 61 years without a history of coronary heart disease at baseline, serum hsCRP was measured using an immunometric assay, and CRF was assessed using a respiratory gas exchange analyzer during exercise testing. hsCRP was categorized as normal and high (≤3 and >3 mg/L, respectively) and CRF as low and high (median cutoff). A total of 148 SCD events occurred during a median follow-up of 28.9 years. Comparing high versus normal hsCRP, the multivariable-adjusted hazard ratio (95% confidence interval) for SCD was 1.65 (1.11 to 2.45), which remained similar on further adjustment for CRF 1.62 (1.09 to 2.40). Comparing high versus low CRF, the multivariable-adjusted hazard ratio for SCD was 0.61 (0.42 to 0.89), which remained persistent after adjustment for hsCRP 0.64 (0.44 to 0.93). Compared with normal hsCRP-low CRF, normal hsCRP-high CRF was associated with a decreased SCD risk of 0.65 (0.43 to 0.99), high hsCRP-low CRF was associated with an increased SCD risk of 1.72 (1.10 to 2.69), with no evidence of a relationship between high hsCRP-high CRF and SCD risk 0.86 (0.39 to 1.88). Positive additive and multiplicative interactions were found between hsCRP and CRF. In a middle-aged Finnish male population, both hsCRP and CRF are independently associated with SCD risk. However, high CRF levels appear to offset the increased SCD risk related to high hsCRP levels.

Emergency vs Delayed Coronary Angiogram in Survivors of Out-of-Hospital Cardiac Arrest: Results of the Randomized, Multicentric EMERGE Trial

Importance

Although an emergency coronary angiogram (CAG) is recommended for patients who experience an out-of-hospital cardiac arrest (OHCA) with ST-segment elevation on the postresuscitation electrocardiogram (ECG), this strategy is still debated in patients without ST-segment elevation.

Objective

To assess the 180-day survival rate with Cerebral Performance Category (CPC) 1 or 2 of patients who experience an OHCA without ST-segment elevation on ECG and undergo emergency CAG vs delayed CAG.

Design, Setting, and Participants

The Emergency vs Delayed Coronary Angiogram in Survivors of Out-of-Hospital Cardiac Arrest (EMERGE) trial randomly assigned survivors of an OHCA without ST-segment elevation on ECG to either emergency or delayed (48 to 96 hours) CAG in 22 French centers. The trial took place from January 19, 2017, to November 23, 2020. Data were analyzed from November 24, 2020, to July 30, 2021.

Main Outcomes and Measures

The primary outcome was the 180-day survival rate with CPC of 2 or less. The secondary end points were occurrence of shock, ventricular tachycardia, and/or fibrillation within 48 hours, change in left ventricular ejection fraction between baseline and 180 days, CPC scale at intensive care unit discharge and day 90, survival rate, and hospital length of stay.

Results

A total of 279 patients (mean [SD] age, 64.7 [14.6] years; 195 men [69.9%]) were enrolled, with 141 (50.5%) in the emergency CAG group and 138 (49.5%) in the delayed CAG group. The study was underpowered. The mean (SD) time delay between randomization and CAG was 0.6 (3.7) hours in the emergency CAG group and 55.1 (37.2) hours in the delayed CAG group. The 180-day survival rates among patients with a CPC of 2 or less were 34.1% (47 of 141) in the emergency CAG group and 30.7% (42 of 138) in the delayed CAG group (hazard ratio [HR], 0.87; 95% CI, 0.65-1.15; P = .32). There was no difference in the overall survival rate at 180 days (emergency CAG, 36.2% [51 of 141] vs delayed CAG, 33.3% [46 of 138]; HR, 0.86; 95% CI, 0.64-1.15; P = .31) and in secondary outcomes between the 2 groups.

Conclusions and Relevance

In this randomized clinical trial, for patients who experience an OHCA without ST-segment elevation on ECG, a strategy of emergency CAG was not better than a strategy of delayed CAG with respect to 180-day survival rate and minimal neurologic sequelae.

Trial Registration

ClinicalTrials.gov Identifier: NCT02876458.

Chronically elevated branched chain amino acid levels are pro-arrhythmic

AIMS

Cardiac arrhythmias comprise a major health and economic burden and are associated with significant morbidity and mortality, including cardiac failure, stroke, and sudden cardiac death (SCD). Development of efficient preventive and therapeutic strategies is hampered by incomplete knowledge of disease mechanisms and pathways. Our aim is to identify novel mechanisms underlying cardiac arrhythmia and SCD using an unbiased approach.

METHODS AND RESULTS

We employed a phenotype-driven N-ethyl-N-nitrosourea mutagenesis screen and identified a mouse line with a high incidence of sudden death at young age (6-9 weeks) in the absence of prior symptoms. Affected mice were found to be homozygous for the nonsense mutation Bcat2p.Q300*/p.Q300* in the Bcat2 gene encoding branched chain amino acid transaminase 2. At the age of 4-5 weeks, Bcat2p.Q300*/p.Q300* mice displayed drastic increase of plasma levels of branch chain amino acids (BCAAs-leucine, isoleucine, valine) due to the incomplete catabolism of BCAAs, in addition to inducible arrhythmias ex vivo as well as cardiac conduction and repolarization disturbances. In line with these findings, plasma BCAA levels were positively correlated to electrocardiogram indices of conduction and repolarization in the German community-based KORA F4 Study. Isolated cardiomyocytes from Bcat2p.Q300*/p.Q300* mice revealed action potential (AP) prolongation, pro-arrhythmic events (early and late afterdepolarizations, triggered APs), and dysregulated calcium homeostasis. Incubation of human pluripotent stem cell-derived cardiomyocytes with elevated concentration of BCAAs induced similar calcium dysregulation and pro-arrhythmic events which were prevented by rapamycin, demonstrating the crucial involvement of mTOR pathway activation.

CONCLUSIONS

Our findings identify for the first time a causative link between elevated BCAAs and arrhythmia, which has implications for arrhythmogenesis in conditions associated with BCAA metabolism dysregulation such as diabetes, metabolic syndrome, and heart failure.

Association between Intra-Arrest Blood Glucose Level and Outcomes of Resuscitation at the Emergency Department: A Retrospective Study

Since current cardiac arrest guidelines do not address the benefit of blood glucose measurement, the ideal ranges and target of blood glucose (BG) levels during cardiac arrest to achieve a better result are warranted. We intended to investigate the associations between intra-arrest BG levels and outcomes of cardiac arrest resuscitation at the emergency department (ED). We conducted a retrospective observational study at a single university hospital. Cardiac arrest patients at the ED between 2017 and 2020 were included. Multivariable logistic regression analysis was performed to examine the associations between intra-arrest BG levels and clinical outcomes. We categorized intra-arrest BG into five groups: <70 mg/dL, 70−99 mg/dL, 100−180 mg/dL, 181−250 mg/dL, and >250 mg/dL. Eight hundred and nineteen patients experienced ED cardiac arrest during the study period. Of all, 385 intra-arrest BG measurements were included in the data analysis. The mean age was 60.4 years. The mean intra-arrest BG level was 171.1 mg/dL, with 64 (16.6%) patients who had intra-arrest BG level below 70 mg/dL and 73 (19.0%) patients who had intra-arrest BG level more than 250 mg/dL. Markedly low (<70 mg/dL) and low (70−99 mg/dL) intra-arrest BG levels were significantly associated with a lower chance of return of spontaneous circulation (ROSC, OR 0.36, 95% CI 0.14−0.99, p = 0.05 and OR 0.33, 95% CI 0.12−0.93, p = 0.04, respectively). For patients who experienced cardiac arrest at the ED, an intra-arrest BG level of less than 100 was inversely correlated with sustained ROSC. Although we could not draw a causal relationship between variables concerning this study design, normalizing intra-arrest BG was shown to result in good clinical outcomes.

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.

Allele-specific silencing by RNAi of R92Q and R173W mutations in cardiac troponin T

Autosomal dominant mutations in sarcomere proteins such as the cardiac troponin T (TNNT2) are the main genetic causes of human hypertrophic cardiomyopathy and dilated cardiomyopathy. Allele-specific silencing by RNA interference (ASP-RNAi) holds promise as a therapeutic strategy for downregulating a single mutant allele with minimal suppression of the corresponding wild-type allele. Here, we propose ASP-RNAi as a possible strategy to specifically knockdown mutant alleles coding for R92Q and R173W mutant TNNT2 proteins, identified in hypertrophic and dilated cardiomyopathy, respectively. Different siRNAs were designed and validated by luciferase reporter assay and following analysis in HEK293T cells expressing either the wild-type or mutant TNNT2 alleles. This study is the first exploration of ASP-RNAi on TNNT2-R173W and TNNT2-R92Q mutations in vitro and gives a base for further application of allele silencing as a therapeutic treatment for TNNT2-mutation-associated cardiomyopathies.

Role of Carotenoids in Cardiovascular Disease

Carotenes are fat-soluble pigments found in a variety of foods, the majority of which are fruits and vegetables. They may have antioxidant biological properties due to their chemical makeup and relationship to cellular membranes. And over 700 carotenoids have been found, with—carotene, lutein, lycopene, and zeaxanthin is the most significant antioxidant food pigments. Their capacity to absorb lipid peroxides, reactive oxygen species (ROS) and nitrous oxide is likely linked to their anti-oxidative properties (NO). The daily requirements for carotenoids are also discussed in this chapter. Heart disease is still a prominent source of sickness and mortality in modern societies. Natural antioxidants contained in fruits and vegetables, such as lycopene, a-carotene, and B-carotene, may help prevent CVD by reducing oxidative stress, which is a major factor in the disease’s progression. Numerous epidemiological studies have backed up the idea that antioxidants might be utilized to prevent and perhaps treat cardiovascular illnesses at a low cost. Supplements containing carotenoids are also available, and their effectiveness has been proven. This article provides an overview of carotenoids’ chemistry, including uptake, transport, availability, metabolism, and antioxidant activity, including its involvement with disease prevention, notably cardiovascular disease.

Novel Indel Variation of NPC1 Gene Associates With Risk of Sudden Cardiac Death

Background and Aims: Sudden cardiac death (SCD) was defined as an unexpected death from cardiac causes during a very short duration. It has been reported that Niemann-Pick type C1 (NPC1) gene mutations might be related to cardiovascular diseases. The purpose of the study is to investigate whether common genetic variants of NPC1 is involved in SCD susceptibility.

Methods: Based on a candidate-gene-based approach and systematic screening strategy, this study analyzed an 8-bp insertion/deletion polymorphism (rs150703258) within downstream of NPC1 for the association with SCD risk in Chinese populations using 158 SCD cases and 524 controls. The association of rs150703258 and SCD susceptibility was analyzed using logistic regression. Genotype-phenotype correlation analysis was performed using public database including 1000G, expression quantitative trait loci (eQTL), and further validated by human heart tissues using PCR. Dual-luciferase assay was used to explore the potential regulatory role of rs150703258. Gene expression profiling interactive analysis and transcription factors prediction were performed.

Results: Logistic regression analysis exhibited that the deletion allele of rs150703258 significantly increased the risk of SCD [odds ratio (OR) = 1.329; 95% confidence interval (95%CI):1.03–1.72; p = 0.0289]. Genotype-phenotype correlation analysis showed that the risk allele was significantly associated with higher expression of NPC1 at mRNA and protein expressions level in human heart tissues. eQTL analysis showed NPC1 and C18orf8 (an adjacent gene to NPC1) are both related to rs150703258 and have higher expression level in the samples with deletion allele. Dual-luciferase activity assays indicate a significant regulatory role for rs150703258. Gene expression profiling interactive analysis revealed that NPC1 and C18orf8 seemed to be co-regulated in human blood, arteries and heart tissues. In silico analysis showed that the rs150703258 deletion variant may create transcription factor binding sites. In addition, a rare 12-bp allele (4-bp longer than the insertion allele) of rs150703258 was discovered in the current cohort.

Conclusion: In summary, our study revealed that rs150703258 might contribute to SCD susceptibility by regulating NPC1 and C18orf8 expression. This indel may be a potential marker for risk stratification and molecular diagnosis of SCD. Validations in different ethnic groups with larger sample size and mechanism explorations are warranted to confirm our findings.

Getting to the heart of rhythm: A century of progress

The human heart beats over eighty thousand times a day, and the average person's heart may have beaten up to 3 billion times by the age of 80. During the early stages of pregnancy, the heart beat provides the first visual and auditory sign of life of the foetus. Conversely, the first audible sound that the foetus is likely to hear is the heart beat of the mother. How fitting then, that at the "birth" Physiological Reviews the very first article published in 1921 written by Eyster and Meek addressed "The origin and conduction of the heart beat".¹ In their insightful review, the authors discussed the landmark discoveries made from the mid-19^th century on the electrical function of the heart. Now, a hundred years later, at the start of the next century of Physiological Reviews, an update on the huge progress made in the "exciting" field of cardiac electrophysiology is warranted. Guided by a number of excellent reviews published in Physiological Reviews since 1921 as well as a large body of literature, an overview of the important advancements made on the topic is provided here.

Racial Disparities in Ion Channelopathies and Inherited Cardiovascular Diseases Associated With Sudden Cardiac Death

Cardiovascular disease (CVD) continues to be the most common cause of death worldwide, and cardiac arrhythmias account for approximately one half of these deaths. The morbidity and mortality from CVD have been reduced significantly over the past few decades; however, disparities in racial or ethnic populations still exist. This review is based on available literature to date and focuses on known cardiac channelopathies and other inherited disorders associated with sudden cardiac death in African American/Black subjects and the role of epigenetics in phenotypic manifestations of CVD, and illustrates existing disparities in treatment and outcomes. The review also highlights the knowledge gaps that limit understanding of the manifestation of phenotypic abnormalities across racial or ethnic groups and discusses disparities associated with device underuse in the management of patients at risk for sudden cardiac death. We discuss factors related to reports in the United States, that the overall mortality attributed to CVD and the number of out-of-hospital cardiac arrests are higher among African American/Black subjects when compared with other racial or ethnic groups. African American/Black subjects are disproportionally affected by CVD, including cardiac arrhythmias and sudden cardiac death, thus highlighting a major concern in this population that remains underrepresented in clinical trials with limited genetic testing and device underuse. The proposed solutions include (1) early identification of genetic variants, which is crucial in tailoring a preventive management strategy; (2) inclusion of diverse racial or ethnic groups in clinical trials; (3) compliance with guideline-directed medical treatment and referral to cardiovascular subspecialists; and (4) training and mentoring of underrepresented junior faculty in cardiovascular health disparities research.

Sex differences in sudden cardiac death in a nationwide study of 54 028 deaths

Objective

Sudden cardiac death (SCD) is a leading cause of death and is more common among males than females. Epidemiological studies of sex differences in SCD cases of all ages are sparse. The aim of this study was to examine differences in incidence rates, clinical characteristics, comorbidities and autopsy findings between male and female SCD cases.

Methods

All deaths in Denmark in 2010 (54 028) were reviewed. Autopsy reports, death certificates, discharge summaries and nationwide health registries were reviewed to identify cases of SCD. Based on the available information, all deaths were subcategorised into definite, probable and possible SCD.

Results

A total of 6867 SCD cases were identified, of which 3859 (56%) were males and 3008 (44%) were females. Incidence rates increased with age and were higher for male population across all age groups in the adult population. Average age at time of SCD was 71 years among males compared with 79 among females (p<0.01). The greatest difference in SCD incidence between males and females was found among the 35–50 years group with an incidence rate ratio of 3.7 (95% CI: 2.8 to 4.8). Compared with female SCD victims, male SCD victims more often had cardiovascular diseases and diabetes mellitus (p<0.01).

Conclusion

This is the first nationwide study of sex differences in SCD across all ages. Differences in incidence rates between males and females were greatest among young adults and the middle-aged. Incidence rates of SCD among older female population approached that of the male population, despite having significantly more cardiovascular disease and diabetes in male SCD cases.

Harmonization of the definition of sudden cardiac death in longitudinal cohorts of the European Sudden Cardiac Arrest network - towards Prevention, Education, and New Effective Treatments (ESCAPE-NET) consortium

BACKGROUND

The burden of sudden cardiac death (SCD) in the general population is substantial and SCD frequently occurs among people with few or no known risk factors for cardiac disease. Reported incidences of SCD vary due to differences in definitions and methodology between cohorts. This study aimed to develop a method for adjudicating SCD cases in research settings and to describe uniform case definitions of SCD in an international consortium harmonizing multiple longitudinal study cohorts.

METHODS

The harmonized SCD definitions include both case definitions using data from multiple sources (eg, autopsy reports, medical history, eyewitnesses) as well as a method using only information from registers (eg, cause of death registers, ICD-10 codes). Validation of the register-based method was done within the consortium using the multiple sources definition as gold standard and presenting sensitivity, specificity, accuracy and positive predictive value.

RESULTS

Consensus definitions of "definite," "possible" and "probable" SCD for longitudinal study cohorts were reached. The definitions are based on a stratified approach to reflect the level of certainty of diagnosis and degree of information. The definitions can be applied to both multisource and register-based methods. Validation of the method using register-information in a cohort comprising 1335 cases yielded a sensitivity of 74%, specificity of 88%, accuracy of 86%, and positive predictive value of 54%.

CONCLUSIONS

This study demonstrated that a harmonization of SCD classification across different methodological approaches is feasible. The developed classification can be used to study SCD in longitudinal cohorts and to merge cohorts with different levels of information.

The role of metabolic syndrome in sudden cardiac death risk: Recent evidence and future directions

Metabolic syndrome (MetS) is a frequent condition whose deleterious effects on the cardiovascular system are often underestimated. MetS is nowadays considered a real pandemic with an estimated prevalence of 25% in general population. Individuals with MetS are at high risk of sudden cardiac death (SCD) as this condition accounts for 50% of all cardiac deaths in such a population. Of interest, recent studies demonstrated that individuals with MetS show 70% increased risk of SCD even without previous history of coronary heart disease (CHD). However, little is known about the interplay between the two conditions. MetS is a complex disease determined by genetic predisposition, unhealthy lifestyle and ageing with deleterious effects on different organs. MetS components trigger a systemic chronic low-grade pro-inflammatory state, associated with excess of sympathetic activity, cardiac hypertrophy, arrhythmias and atherosclerosis. Thus, MetS has an important burden on the cardiovascular system as demonstrated by both preclinical and clinical evidence. The aim of this review is to summarize recent evidence concerning the association between MetS and SCD, showing possible common aetiological processes, and to indicate prospective for future studies and therapeutic targets.

Current and investigational therapies for the treatment of refractory ventricular fibrillation

DISCLAIMER

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

Esmolol, dual sequential defibrillation, vector change defibrillation, and left stellate ganglion block are presented and reviewed for the treatment of refractory ventricular fibrillation.

SUMMARY

Although no formal definition has been established for refractory ventricular fibrillation, the literature describes it as a pulseless ventricular arrhythmia that persists despite 3 standard defibrillation attempts, administration of amiodarone 300 mg intravenously, and provision of three 1-mg intravenous doses of epinephrine. Evolving literature surrounding resuscitation in this particular subset of cardiac arrest challenges the efficacy of traditional therapies, such as epinephrine, and suggests that other treatment modalities may improve outcomes. Case reports, case series, and small retrospective studies have pointed to benefit when utilizing a variety of therapies, namely, esmolol, dual sequential defibrillation, vector change defibrillation, or left stellate ganglion block, in patients with refractory ventricular fibrillation arrest.

CONCLUSION

A mounting, although limited, body of evidence suggests that esmolol, dual sequential defibrillation, vector change defibrillation, or left stellate ganglion block may be effective at terminating refractory ventricular fibrillation and improving patient outcomes. Further evidence is required before these therapies can be adopted as standard practice; however, as key members of the code response team, it is imperative for pharmacists to be familiar with the supporting evidence, safety considerations, and logistical challenges of utilizing these treatments during arrest.

Sudden cardiac death in diabetes and obesity: mechanisms and therapeutic strategies

Ventricular arrhythmias and sudden cardiac death (SCD) occur most frequently in the setting of coronary artery disease, cardiomyopathy and heart failure, but are also increasingly observed in individuals suffering from diabetes mellitus and obesity. The incidence of these metabolic disorders is rising in Western countries, but adequate prevention and treatment of arrhythmias and SCD in affected patients is limited due to our incomplete knowledge of the underlying disease mechanisms. Here, an overview is presented of the prevalence of electrophysiological disturbances, ventricular arrhythmias and SCD in the clinical setting of diabetes and obesity. Experimental studies are reviewed, which have identified disease pathways and associated modulatory factors, in addition to pro-arrhythmic mechanisms. Key processes are discussed, including mitochondrial dysfunction, oxidative stress, cardiac structural derangements, abnormal cardiac conduction, ion channel dysfunction, prolonged repolarization and dysregulation of intracellular sodium and calcium homeostasis. In addition, the recently identified pro-arrhythmic effects of dysregulated branched chain amino acid metabolism, a common feature in patients with metabolic disorders, are addressed. Finally, current management options are discussed, in addition to the potential development of novel preventive and therapeutic strategies based on recent insight gained from translational studies.

Coronary Calcium Scanning and Cardiovascular Risk Assessment Among Firefighters

INTRODUCTION

Sudden cardiac death is the main cause of death among firefighters. The goal of this study is to identify firefighters at risk for cardiovascular disease using coronary artery calcium screening.

METHODS

Asymptomatic firefighters aged ≥40 years without known cardiovascular disease or diabetes (N=487) were recruited from fire departments in 3 Maryland counties from 2016 to 2018, with data analysis from 2018 to 2019. The cardiovascular disease prevention program included an evaluation of blood pressure, cholesterol, BMI, fasting glucose, medications, and a coronary calcium scan. A subset (n=100) was evaluated in more detail, including family history, metabolic syndrome, diet, exercise, smoking, and atherosclerotic cardiovascular disease risk score.

RESULTS

Results indicated that 191 (39%) firefighters had a coronary artery calcium score >0, of which 91% were above the average for age, sex, and ethnicity. On univariable logistic regression, older age, male sex, hypertension, BMI, and glucose were significantly (p<0.05) associated with a higher likelihood of having any coronary artery calcium. Multiple logistic regression found that older age; male sex; taking lipid-lowering or antihypertensive medications; and higher low-density lipoprotein cholesterol, BMI, and fasting blood glucose were significantly associated with a higher likelihood of having coronary artery calcium. Of those with coronary artery calcium, 141 (74%) were not on lipid-lowering medication. In addition, 47 (94%) of those on lipid-lowering medication had a low-density lipoprotein cholesterol >70 mg/dL. In the detailed subset, 30 (30%) had coronary artery calcium. Among these, 28 (93%) had an atherosclerotic cardiovascular disease risk score <7.5%. Thus, if atherosclerotic cardiovascular disease scores alone were used to assess risk in this subset, an opportunity would have been missed to identify and treat firefighters who may have benefited from more aggressive treatment.

CONCLUSIONS

A coronary artery calcium scan may identify the firefighters at increased risk for cardiovascular disease. A comprehensive cardiovascular disease prevention program implemented early in a firefighter's career may help reduce cardiovascular disease risk and thus death and disability in this high-risk population.

Targeting Parasympathetic Activity to Improve Autonomic Tone and Clinical Outcomes

In this review we will briefly summarize the evidence that autonomic imbalance, more specifically reduced parasympathetic activity to the heart, generates and/or maintains many cardiorespiratory diseases and will discuss mechanisms and sites, from myocytes to the brain, that are potential translational targets for restoring parasympathetic activity and improving cardiorespiratory health.

Sudden unexpected death in Parkinson's disease: Insights from clinical practice

Classified as the second most common neurodegenerative disorder associated with aging after Alzheimer's disease, Parkinson's disease (PD) is the most common movement disorder. In the last decade, despite advances in treatment, mortality rates linked with PD continued to reach significant figures. Available studies have shown that compared with healthy controls, patients with PD are accompanied by high rates of premature death. This is usually caused by factors such as pneumonia and cerebrovascular and cardiovascular diseases. Recently, it has been demonstrated that a significant proportion of patients with PD die suddenly. This is referred to as a sudden and unexpected death in PD (SUDPAR). Here, we focus on the magnitude of SUDPAR. Finally, it is important to learn more about SUDPAR for the implementation of effective prevention strategies.