The spectrum of epidemiology underlying sudden cardiac death

Management of ST Elevation Myocardial Infarction (STEMI) in Different Settings

ST-segment elevation myocardial infarction (STEMI) is a life-threatening condition that requires emergent, complex, well-coordinated treatment. Although the primary goal of treatment is simple to describe-reperfusion as quickly as possible-the management process is complicated and is affected by multiple factors including location, patient, and practitioner characteristics. Hence, this narrative review will discuss the recommended management and treatment strategies of STEMI in the circumstances.

Temporal trends and sex differences in sudden cardiac death in the Copenhagen City Heart Study

OBJECTIVE

More knowledge about the development of sudden cardiac death (SCD) in the general population is needed to develop meaningful predictors of SCD. Our aim with this study was to estimate the incidence of SCD in the general population and examine the temporal changes, demographics and clinical characteristics.

METHODS

All participants in the Copenhagen City Heart Study were followed from 1993 to 2016. All death certificates, autopsy reports and national registry data were used to identify all cases of SCD.

RESULTS

A total of 14 562 subjects were included in this study. There were 8394 deaths with all information available, whereof 1335 were categorised as SCD. The incidence of SCD decreased during the study period by 41% for persons aged 40-90 years, and the standardised incidence rates decreased from 504 per 100 000 person-years (95% CI 447 to 569) to 237 per 100 000 person-years (95% CI 195 to 289). The incidence rate ratio of SCD between men and women ≤75 years was 1.99 (95% CI 1.62 to 2.46). The proportion of SCD of all cardiac deaths decreased during the observation period and decreased with increasing age. Men had more cardiovascular comorbidities (OR 1.34, 95% CI 1.07 to 1.68, p<0. 01), and SCD was the first registered manifestation of cardiac disease in 50% of all cases.

CONCLUSION

The incidence of SCD in the general population has declined significantly during the study period but should be further investigated for more recent variations as well as novel risk predictors for persons with low to medium risk of SCD.

Does the Age of Sudden Cardiac Death in Family Members Matter in Brugada Syndrome?

Background Brugada syndrome is an inherited cardiac channelopathy associated with major arrhythmic events (MAEs). The presence of a positive family history of sudden cardiac death (SCD) as a risk predictor of MAE remains controversial. We aimed to examine the association between family history of SCD and MAEs stratified by age of SCD with a systematic review and meta-analysis. Methods and Results We searched the databases of MEDLINE and EMBASE from January 1992 to January 2020. Data from each study were combined using the random-effects model. Fitted metaregression was performed to evaluate the association between the age of SCD in families and the risk of MAE. Twenty-two studies from 2004 to 2019 were included in this meta-analysis involving 3386 patients with Brugada syndrome. The overall family history of SCD was not associated with increased risk of MAE in Brugada syndrome (pooled odds ratio [OR], 1.11; 95% CI, 0.82-1.51; P=0.489, I²=45.0%). However, a history of SCD in family members of age younger than 40 years of age did increase the risk of MAE by ≈2-fold (pooled OR, 2.03; 95% CI, 1.11-3.73; P=0.022, I²=0.0%). When stratified by the age of cut point at 50, 45, 40, and 35 years old, a history of SCD in younger family member was significantly associated with a higher risk of MAE (pooled OR, 0.49, 1.30, 1.51, and 2.97, respectively; P=0.046). Conclusions A history of SCD among family members of age younger than 40 years was associated with a higher risk of MAE.

Simple electrocardiographic measures improve sudden arrhythmic death prediction in coronary disease

AIMS

To determine whether the combination of standard electrocardiographic (ECG) markers reflecting domains of arrhythmic risk improves sudden and/or arrhythmic death (SAD) risk stratification in patients with coronary heart disease (CHD).

METHODS AND RESULTS

The association between ECG markers and SAD was examined in a derivation cohort (PREDETERMINE; N = 5462) with adjustment for clinical risk factors, left ventricular ejection fraction (LVEF), and competing risk. Competing outcome models assessed the differential association of ECG markers with SAD and competing mortality. The predictive value of a derived ECG score was then validated (ARTEMIS; N = 1900). In the derivation cohort, the 5-year cumulative incidence of SAD was 1.5% [95% confidence interval (CI) 1.1-1.9] and 6.2% (95% CI 4.5-8.3) in those with a low- and high-risk ECG score, respectively (P for Δ < 0.001). A high-risk ECG score was more strongly associated with SAD than non-SAD mortality (adjusted hazard ratios = 2.87 vs. 1.38 respectively; P for Δ = 0.003) and the proportion of deaths due to SAD was greater in the high vs. low risk groups (24.9% vs. 16.5%, P for Δ = 0.03). Similar findings were observed in the validation cohort. The addition of ECG markers to a clinical risk factor model inclusive of LVEF improved indices of discrimination and reclassification in both derivation and validation cohorts, including correct reclassification of 28% of patients in the validation cohort [net reclassification improvement 28 (7-49%), P = 0.009].

CONCLUSION

For patients with CHD, an externally validated ECG score enriched for both absolute and proportional SAD risk and significantly improved risk stratification compared to standard clinical risk factors including LVEF.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT01114269. ClinicalTrials.gov ID NCT01114269.

Evaluation of histopathological findings of cardiac deaths in forensic autopsies

BACKGROUND

The vast majority of sudden and unexpected natural deaths are related to cardiovascular diseases, especially coronary artery diseases.

AIMS

In this study, we aimed to reveal the epidemiological differences between men and women and to investigate the most common pathologies that cause cardiac deaths.

METHODS

Five thousand seven hundred sixty-eight autopsy cases that were done in 2016 were reviewed for the autopsy information and histopathological findings. Of the 5768 autopsies performed, 866 were due to cardiac causes. Eight hundred thirty-two cases were reviewed due to lack of autopsy information in 34 cases.

RESULTS

One hundred sixteen (13.9%) were female, and 716 (86.1%) were male. Coronary artery disease was detected in 760 of 832 cases. There were findings of acute or previous myocardial infarction in 595 (71.5%), perivascular and interstitial fibrosis in 159 (19.1%), myocardial rupture and tamponade in 31 (%3.7), valvular disease in 6 (0.7%), cardiomyopathy in 4 (0.5%), and congenital heart disease in 3 (0.4%). In the study, it was observed that the mean age of death due to cardiac pathology other than coronary artery disease was significantly lower than deaths due to coronary artery disease (p < 0.05). The presence of coronary artery disease in men was found to be significantly higher than in women (p < 0.001).

CONCLUSION

In our study, it was found that deaths due to coronary artery disease are seen at an older age than cardiac deaths other than coronary artery disease. In addition, in line with current knowledge, it has been confirmed that the mortality rate of coronary artery disease is higher in men than in women.

Nationwide burden of sudden cardiac death: A study of 54,028 deaths in Denmark

BACKGROUND

A large proportion of all deaths are sudden cardiac deaths (SCDs). Reliable estimates of nationwide incidence of SCD, however, are missing.

OBJECTIVES

The goals of this study were to estimate SCD burden across all age groups in Denmark and to compare it with the estimates of other common causes of death.

METHODS

All deaths in Denmark (population of 5.5 million) in 2010 were manually reviewed case by case. Autopsy reports, death certificates, and information from nationwide health registries were systematically examined to identify all SCD cases in 2010. According to the level of detail of the available information, all deaths were categorized as either non-SCD, definite SCD, probable SCD, or possible SCD.

RESULTS

There were 54,028 deaths in Denmark in 2010, of which 6867 (13%) were categorized as SCD (591 (9%) definite SCD, 1568 (23%) probable SCD, and 4708 (68%) possible SCD). The incidence rate of definite SCD was 11 (95% confidence interval 10-12) per 100,000 person-years. Including definite, probable, and possible SCD cases, the highest possible overall SCD incidence rate was 124 (95% confidence interval 121-127) per 100,000 person-years. Estimated SCD burden was similar to or greater than the estimates of all other common causes of death. Of all SCD cases, 49% were not diagnosed with cardiovascular disease before death.

CONCLUSION

SCD accounted for up to 13% of all deaths. Almost half of all SCD cases occurred in persons without a history of cardiovascular disease. Consequently, the optimization of risk stratification and prevention of SCD in the general population should be given high priority.

Inherited arrhythmia syndrome predisposing to sudden cardiac death

Inherited arrhythmia (IA) is one of the main causes of sudden cardiac death (SCD) in young people, and is reported to be a more prevalent cause of SCD in Asia than in Western countries. IAs are a group of genetic disorders caused by mutations in genes encoding cardiac ion channels, leading to electrophysiological characteristics that often occur in the absence of structural abnormalities. Channelopathies, such as long QT syndrome and Brugada syndrome, carry a potential risk of life-threatening ventricular tachyarrhythmias that predispose to SCD, although early prediction and prevention of the risk remain challenging. Recent advances in genetic testing have facilitated risk stratification as well as a precise diagnosis for IA, despite ongoing debates about the implications. Herein, we provide epidemiological data, a pathophysiological overview, and the current clinical approach to IAs related to SCD. In addition, we review the general issues arising from genetic testing for IAs.

Factors Predisposing to Survival After Resuscitation for Sudden Cardiac Arrest

BACKGROUND

In the POST SCD study, the authors autopsied all World Health Organization (WHO)-defined sudden cardiac deaths (SCDs) and found that only 56% had an arrhythmic cause; resuscitated sudden cardiac arrests (SCAs) were excluded because they did not die suddenly. They hypothesized that causes underlying resuscitated SCAs would be similarly heterogeneous.

OBJECTIVES

The aim of this study was to determine the causes and outcomes of resuscitated SCAs.

METHODS

The authors identified all out-of-hospital cardiac arrests (OHCAs) from February 1, 2011, to January 1, 2015, of patients aged 18 to 90 years in San Francisco County. Resuscitated SCAs were OHCAs surviving to hospitalization and meeting WHO criteria for suddenness. Underlying cause was determined by comprehensive record review.

RESULTS

The authors identified 734 OHCAs over 48 months; 239 met SCA criteria, 133 (55.6%) were resuscitated to hospitalization, and 47 (19.7%) survived to discharge. Arrhythmic causes accounted for significantly more resuscitated SCAs overall (92 of 133, 69.1%), particularly among survivors (43 of 47, 91.5%), than WHO-defined SCDs in POST SCD (293 of 525, 55.8%; p < 0.004 for both). Among resuscitated SCAs, arrhythmic cause, ventricular tachycardia/fibrillation initial rhythm, and white race were independent predictors of survival. None of the resuscitated SCAs due to neurologic causes survived.

CONCLUSIONS

In this 4-year countywide study of OHCAs, only one-third were sudden, of which one-half were resuscitated to hospitalization and 1 in 5 survived to discharge. Arrhythmic cause predicted survival and nearly one-half of nonsurvivors had nonarrhythmic causes, suggesting that SCA survivors are not equivalent to SCDs. Early identification of nonarrhythmic SCAs, such as neurologic emergencies, may be a target to improve OHCA survival.

Retrospective Analysis of Sudden Cardiac Deaths in a 10-Year Autopsy Series in the City of Isparta in Turkey

Sudden cardiac death (SCD) is an important public health problem that accounts for approximately 15% to 20% of global deaths. Our retrospective study aimed to analyze etiological distribution and epidemiological data of 128 cases with SCD as death cause based on autopsies between 2010 and 2019. The mean age of SCD cases was 57.09, with the highest incidence in older than 60 years (43.8%). Male/female ratio was 4.5:1, peaking with 9.2:1 in the 41- to 60-year age group. Deaths occurred mostly at home (41.4%). Coronary atherosclerotic heart disease (CAD) was main SCD cause (65.6%) with cardiac tamponade (10.9%), unexplained SCD (8.6%), and hypertrophic cardiomyopathy (7.8%) after it. A total of 71.2% of CAD cases had coronary artery stenosis of greater than 75% and 92.9% had atherosclerotic degeneration in the left anterior descending artery. Based on the body mass index-based normal heart weights table, 91.7% of CAD cases had cardiomegaly. This study showed CAD, cardiomegaly, and high body mass index concurrence as a very important SCD risk. Because SCD incidence increases in older than 40 years, determining risk groups through regular medical examinations and inspections, older than 30 years would provide implementation of preventive measures. Some cardiac diseases causing sudden death are undetectable despite detailed autopsy and histopathological examinations. Including postmortem cardiogenetic analysis among routine techniques in sudden deaths would lower sudden unexplained death diagnosis rates.

Sex and Racial Differences in Autopsy-Defined Causes of Presumed Sudden Cardiac Death

[Figure: see text].

Changes in Cardiovascular Health Status and Risk of Sudden Cardiac Death in Older Adults

PURPOSE

Cardiovascular health (CVH) status is associated with several cardiovascular outcomes; however, correlations between changes in CVH status and risk of sudden cardiac death (SCD) are unknown. We aimed to evaluate associations between changes in CVH status and risk of SCD and all-cause death in older adults.

MATERIALS AND METHODS

We used data from the Korea National Health Insurance Service-Senior cohort database (2005-2012). Six metrics from the American Heart Association (smoking, body mass index, physical activity, blood pressure, total cholesterol, and fasting blood glucose) were used to calculate CVH scores. Changes in CVH status between two health checkups were categorized as low to low, low to high, high to low, and high to high.

RESULTS

We included 105200 patients whose CVH status for an initial and follow-up health checkup (2-year interval) was available. During a median of 5.2 years of follow-up after a second health checkup, 688 SCDs occurred. Compared to patients with a persistent low CVH status, those with a consistently high CVH status had a reduced risk of SCD [adjusted hazard ratio (HR), 0.69; 95% confidence interval (CI), 0.56-0.86] and all-cause death (adjusted HR, 0.74; 95% CI, 0.69-0.78). The risk of all-cause death followed similar trends. However, an inconsistent linear relationship was observed for changes in CVH status and the risk of SCD, but not of all-cause death.

CONCLUSION

Maintaining a high CVH status was associated with future risks of SCD and all-cause death among an older adult population.

Age Effect on Incidence, Physical, and Psychiatric Comorbidity for Sudden Cardiac Death in Schizophrenia: Effet de l'âge sur l'incidence, la comorbidité physique et psychiatrique de la mort cardiaque subite dans la schizophrénie

OBJECTIVE

The pathogenesis of sudden cardiac death may differ between younger and older adults in schizophrenia, but evidence remains scant. This study investigated the age effect on the incidence and risk of the physical and psychiatric comorbidity for sudden cardiac death.

METHODS

Using 2000 to 2016 data from the Taiwan National Health Insurance Research Database and Department of Health Death Certification System, we identified a national cohort of 170,322 patients with schizophrenia, 1,836 of whom had a sudden cardiac death. Standardized mortality ratios (SMRs) were estimated. Hazard ratios and population attributable fractions of distinctive comorbidities for sudden cardiac death were assessed.

RESULTS

The SMRs of sudden cardiac death were all >1.00 across each age group for both sexes, with the highest SMR in male patients aged <35 years (30.88, 95% CI: 26.18-36.18). The fractions of sudden cardiac death attributable to hypertension and congestive heart failure noticeably increased with age. By contrast, the fraction attributable to drug-induced mental disorder decreased with age. Additionally, chronic hepatic disease and sleep disorder increased the risk of sudden cardiac death in patients aged <35 years. Dementia and organic mental disorder elevated the risk in patients aged between 35-54 years. Ischemic heart disease raised the risk in patients aged ≥55 years.

CONCLUSIONS

The risk is increased across the lifespan in schizophrenia, particularly for younger male patients. Furthermore, physical and psychiatric comorbidities have age-dependent risks. The findings suggest that prevention strategies targeted toward sudden cardiac death in patients with schizophrenia must consider the age effect.

European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances

These European Resuscitation Council (ERC) Cardiac Arrest in Special Circumstances guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required to basic and advanced life support for the prevention and treatment of cardiac arrest in special circumstances; specifically special causes (hypoxia, trauma, anaphylaxis, sepsis, hypo/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), special settings (operating room, cardiac surgery, catheter laboratory, dialysis unit, dental clinics, transportation (in-flight, cruise ships), sport, drowning, mass casualty incidents), and special patient groups (asthma and COPD, neurological disease, obesity, pregnancy).

Sudden Cardiac Death-A New Insight Into Potentially Fatal Genetic Markers

Sudden cardiac death (SCD) is an unexpected and dramatic event. It draws special attention especially in young, seemingly healthy athletes. Our scientific paper is based on the death of a young, 23-year-old professional footballer, who died on the football field after a two-year history of cardiac symptoms. In this study we analyzed clinical, ECG and laboratory data, as well as results of genetic testing analysis in family members. To elucidate potential genetic etiology of SCD in this family, our analysis included 294 genes related to various cardiac conditions.

Post-Stroke Cardiovascular Complications and Neurogenic Cardiac Injury: JACC State-of-the-Art Review

Over 1.5 million deaths worldwide are caused by neurocardiogenic syndromes. Furthermore, the consequences of deleterious brain-heart interactions are not limited to fatal complications. Cardiac arrhythmias, heart failure, and nonfatal coronary syndromes are also common. The brain-heart axis is implicated in post-stroke cardiovascular complications known as the stroke-heart syndrome, sudden cardiac death, and Takotsubo syndrome, among other neurocardiogenic syndromes. Multiple pathophysiological mechanisms with the potential to be targeted with novel therapies have been identified in the last decade. In the present state-of-the-art review, we describe recent advances in the understanding of anatomical and functional aspects of the brain-heart axis, cardiovascular complications after stroke, and a comprehensive pathophysiological model of stroke-induced cardiac injury.

Arrhythmogenic effects of ultra-long and bistable cardiac action potentials

Contemporary accounts of the initiation of cardiac arrhythmias typically rely on after-depolarizations as the trigger for reentrant activity. The after-depolarizations are usually triggered by calcium entry or spontaneous release within the cells of the myocardium or the conduction system. Here we propose an alternative mechanism whereby arrhythmias are triggered autonomously by cardiac cells that fail to repolarize after a normal heartbeat. We investigated the proposal by representing the heart as an excitable medium of FitzHugh-Nagumo cells where a proportion of cells were capable of remaining depolarized indefinitely. As such, those cells exhibit bistable membrane dynamics. We found that heterogeneous media can tolerate a surprisingly large number of bistable cells and still support normal rhythmic activity. Yet there is a critical limit beyond which the medium is persistently arrhythmogenic. Numerical analysis revealed that the critical threshold for arrhythmogenesis depends on both the strength of the coupling between cells and the extent to which the abnormal cells resist repolarization. Moreover, arrhythmogenesis was found to emerge preferentially at tissue boundaries where cells naturally have fewer neighbors to influence their behavior. These findings may explain why atrial fibrillation typically originates from tissue boundaries such as the cuff of the pulmonary vein.

Cardiac fibrillation is a medical condition where normal heart function is compromised as electrical activity becomes disordered. How fibrillation arises spontaneously is not fully understood. It is generally thought to be triggered by premature depolarization of the cardiac action potential in one or more cells. Those premature beats, known as after-depolarizations, subsequently initiate a self-sustaining rotor in the otherwise normal heart tissue. In this study, we propose an alternative mechanism whereby arrhythmias are initiated by cardiac cells that fail to repolarize of their own accord but still operate normally when embedded in functional heart tissue. We find that such cells can act as focal ectopic sources under appropriate conditions of inter-cellular coupling. Moreover, those cells are more prone to initiating arrhythmia when they are located on natural tissue boundaries. This may explain why atrial fibrillation typically originates from the site where the pulmonary vein attaches to the wall of the heart.

The increased risk of atrial fibrillation in inflammatory arthritis: a systematic review and meta-analysis of cohort studies

Background: Atrial fibrillation (AF) is the most common cardiac arrhythmia contributing to stroke and sudden cardiac death. Numbers of studies indicated that patients with inflammatory arthritis have an increased risk of AF. The present study aims to assess the risk of AF in inflammatory arthritis patients.Methods: We systematically searched cohort studies regarding the risk of AF in patients with rheumatoid arthritis, or spondyloarthritis through PubMed, Web of Science, Cochrane Library, Clinical Trials Registry, and China National Knowledge from inception to August 1, 2019. Meta-analysis was performed using fixed effect model, estimating both crude and adjusted hazard ratios (HRs) with 95% confidence intervals (CIs). Subgroup analysis and meta-regression based on geographic characteristics, comorbidities, and medication use were conducted to explore the source of heterogeneity.Results: Literature search identified 388 potentially relevant studies, and five studies containing seven cohorts of rheumatoid arthritis or spondyloarthritis were included in the meta-analysis. The AF risk of inflammatory arthritis patients was significantly increased compared with health controls (HR = 1.42, 95% CI: 1.36 to 1.49, Z = 14.17, P < .001), and the pooled HR of studies adjusted factor, like demographic characteristics, medications use, and comorbidities, was 1.37 (95% CI: 1.29 to 1.46; Z = 9.82, P < .001).Conclusion: Patients with inflammatory arthritis have increased risk of AF, probably due to the underlying chronic inflammation. Although various confounders have been adjusted like medications use and comorbidities, the risk of AF is still significantly increased in inflammatory arthritis patients.Abbreviations: AF: Atrial fibrillation; AS: Ankylosing spondylitis; CI: Confidence interval; HR: Hazard ratio; NOS: Newcastle-Ottawa scale; NSAIDs: Non-steroid anti-inflammatory drugs; PsA: Psoriatic arthritis; RA: Rheumatoid arthritis; SpA: Spondyloarthritis; TNFi: Tumor necrosis factors inhibitor; uSpA: Undifferentiated spondyloarthritis.

Comprehensive Analysis of ceRNA Regulation Network Involved in the Development of Coronary Artery Disease

Background

Coronary artery disease (CAD) is one of the most common causes of sudden death with high morbidity in recent years. This paper is aimed at exploring the early peripheral blood biomarkers of sudden death and providing a new perspective for clinical diagnosis and forensic pathology identification by integrated bioinformatics analysis.

Methods

Two microarray expression profiling datasets (GSE113079 and GSE31568) were downloaded from the Gene Expression Omnibus (GEO) database, and we identified differentially expressed lncRNAs, miRNAs, and mRNAs in CAD. Gene Ontology (GO) and KEGG pathway analyses of DEmRNAs were executed. A protein-protein interaction (PPI) network was constructed, and hub genes were identified. Finally, we constructed a competitive endogenous RNA (ceRNA) regulation network among lncRNAs, miRNAs, and mRNAs. Also, the 5 miRNAs of the ceRNA network were verified by RT-PCR.

Results

In total, 86 DElncRNAs, 148 DEmiRNAs, and 294 DEmRNAs were dysregulated in CAD. We received 12 GO terms and 5 pathways of DEmRNAs. 31 nodes and 78 edges were revealed in the PPI network. The top 10 genes calculated by degree method were identified as hub genes. Moreover, there were a total of 26 DElncRNAs, 5 DEmiRNAs, and 13 DEmRNAs in the ceRNA regulation network. We validated the 5 miRNAs of the ceRNA network by RT-PCR, which were consistent with the results of the microarray.

Conclusions

In this paper, a CAD-specific ceRNA network was successfully constructed, contributing to the understanding of the relationship among lncRNAs, miRNAs, and mRNAs. We identified potential peripheral blood biomarkers in CAD and provided novel insights into the development and progress of CAD.

Regulation of muscle potassium: exercise performance, fatigue and health implications

This review integrates from the single muscle fibre to exercising human the current understanding of the role of skeletal muscle for whole-body potassium (K⁺) regulation, and specifically the regulation of skeletal muscle [K⁺]. We describe the K⁺ transport proteins in skeletal muscle and how they contribute to, or modulate, K⁺ disturbances during exercise. Muscle and plasma K⁺ balance are markedly altered during and after high-intensity dynamic exercise (including sports), static contractions and ischaemia, which have implications for skeletal and cardiac muscle contractile performance. Moderate elevations of plasma and interstitial [K⁺] during exercise have beneficial effects on multiple physiological systems. Severe reductions of the trans-sarcolemmal K⁺ gradient likely contributes to muscle and whole-body fatigue, i.e. impaired exercise performance. Chronic or acute changes of arterial plasma [K⁺] (hyperkalaemia or hypokalaemia) have dangerous health implications for cardiac function. The current mechanisms to explain how raised extracellular [K⁺] impairs cardiac and skeletal muscle function are discussed, along with the latest cell physiology research explaining how calcium, β-adrenergic agonists, insulin or glucose act as clinical treatments for hyperkalaemia to protect the heart and skeletal muscle in vivo. Finally, whether these agents can also modulate K⁺-induced muscle fatigue are evaluated.

Anxiety, Mental Stress, and Sudden Cardiac Arrest: Epidemiology, Possible Mechanisms and Future Research

Sudden cardiac arrest (SCA) is a leading cause of mortality and morbidity in affluent societies, which underscores the need to identify persons at risk. The etiology of SCA is however complex, with predisposing and precipitating factors interacting. Although anxiety and mental stress have been linked to SCA for decades, their precise role and impact remain unclear and the biological underpinnings are insufficiently understood. In this paper, we systematically reviewed various types of observational studies (total n = 20) examining the association between anxiety or mental stress and SCA. Multiple methodological considerations challenged the summarizing and interpretation of the findings. For anxiety, the overall picture suggests that it predisposes for SCA in physically healthy populations (unadjusted OR = 2.44; 95% CI: 1.06-5.59; n = 3). However, in populations at risk for SCA (n = 4), associations were heterogeneous but not significant. Anxiety may partly predispose to SCA by contributing to other risk factors such as cardiovascular disease and diabetes mellitus via mechanisms such as unhealthy lifestyle and metabolic abnormalities. Mental stress appears to precipitate SCA, presumably by more directly impacting on the cardiac ion channels that control the heart's electrical properties. This may lead to ventricular fibrillation, the arrhythmia that underlies SCA. To advance this field of research, experimental studies that unravel the underlying biological mechanisms are deemed important, and most easily designed for mental stress as a precipitating factor because of the short timeframe. These proof-of-concept studies should examine the whole pathway from the brain to the autonomic nervous system, and eventually to cardiac ion channels. Ultimately, such studies may facilitate the identification of persons at risk and the development of novel preventive strategies.

Circadian Rhythms of Early Afterdepolarizations and Ventricular Arrhythmias in a Cardiomyocyte Model

Sudden cardiac arrest is a malfunction of the heart's electrical system, typically caused by ventricular arrhythmias, that can lead to sudden cardiac death (SCD) within minutes. Epidemiological studies have shown that SCD and ventricular arrhythmias are more likely to occur in the morning than in the evening, and laboratory studies indicate that these daily rhythms in adverse cardiovascular events are at least partially under the control of the endogenous circadian timekeeping system. However, the biophysical mechanisms linking molecular circadian clocks to cardiac arrhythmogenesis are not fully understood. Recent experiments have shown that L-type calcium channels exhibit circadian rhythms in both expression and function in guinea pig ventricular cardiomyocytes. We developed an electrophysiological model of these cells to simulate the effect of circadian variation in L-type calcium conductance. In our simulations, we found that there is a circadian pattern in the occurrence of early afterdepolarizations (EADs), which are abnormal depolarizations during the repolarization phase of a cardiac action potential that can trigger fatal ventricular arrhythmias. Specifically, the model produces EADs in the morning, but not at other times of day. We show that the model exhibits a codimension-2 Takens-Bogdanov bifurcation that serves as an organizing center for different types of EAD dynamics. We also simulated a two-dimensional spatial version of this model across a circadian cycle. We found that there is a circadian pattern in the breakup of spiral waves, which represents ventricular fibrillation in cardiac tissue. Specifically, the model produces spiral wave breakup in the morning, but not in the evening. Our computational study is the first, to our knowledge, to propose a link between circadian rhythms and EAD formation and suggests that the efficacy of drugs targeting EAD-mediated arrhythmias may depend on the time of day that they are administered.

Oxidized Low-Density Lipoprotein Associates with Ventricular Stress in Young Adults and Triggers Intracellular Ca2+ Alterations in Adult Ventricular Cardiomyocytes

Oxidized low-density lipoprotein (oxLDL) is associated with cardiac damage and causes injury to multiple cell types. We aimed to investigate the role of oxLDL in ventricular stress. We first examined the association between circulating oxLDL and N-terminal pro-brain natriuretic peptide (NT-proBNP), a marker of myocardial stress, in young subjects (30-50 years) with or without stable coronary artery disease (SCAD). oxLDL and NT-proBNP were significantly higher in subjects at high cardiovascular risk (CVR) than in subjects at low CVR and were associated independently of traditional CVR factors and C-reactive protein. Furthermore, the levels of oxLDL and NT-proBNP were significantly lower in subjects with SCAD than in peers at high CVR. To determine the intracellular mechanisms involved in the cardiac effects of oxLDL, we analyzed the in vitro effect of oxLDL on intracellular Ca²⁺ handling in adult rat ventricular cardiomyocytes using confocal microscopy. Acute challenge of adult ventricular cardiomyocytes to oxLDL reduced systolic Ca²⁺ transients and sarcoplasmic reticulum Ca²⁺ load. Moreover, diastolic spontaneous Ca²⁺ leak increased significantly after acute exposure to oxLDL. Thus, we demonstrate that oxLDL associates with NT-proBNP in young subjects, and can directly induce Ca²⁺ mishandling in adult ventricular cardiomyoyctes, predisposing cardiomyocytes to cardiac dysfunction and arrhythmogenicity.

The cardiac arrest centre for the treatment of sudden cardiac arrest due to presumed cardiac cause: aims, function, and structure: position paper of the ACVC association of the ESC, EAPCI, EHRA, ERC, EUSEM, and ESICM

Approximately 10% of patients resuscitated from out-of-hospital cardiac arrest (OHCA) survive to hospital discharge. Improved management to improve outcomes are required, and it is proposed that such patients should be preferentially treated in cardiac arrest centres (CACs). The minimum requirements of therapy modalities for the CAC are 24/7 availability of an on-site coronary angiography laboratory, an emergency department, an intensive care unit, imaging facilities, such as echocardiography, computed tomography, and magnetic resonance imaging, and a protocol outlining transfer of selected patients to CACs with additional resources (OHCA hub hospitals). These hub hospitals are regularly treating a high volume of patients and offer further treatment modalities. This consensus document describes the aims, the minimal requirements for therapeutic modalities and expertise, and the structure, of a CAC. It represents a consensus among the major European medical associations and societies involved in the treatment of OHCA patients.

Sudden cardiac arrest in epilepsy patients undergoing continuous video electroencephalogram monitoring: The national inpatient sample

OBJECTIVE

To examine the relationship between epilepsy and sudden cardiac arrest (SCA) and identify clinical and healthcare system related predictors of SCA in patients with a discharge diagnosis of epilepsy undergoing continuous video EEG (cVEEG) monitoring.

METHODS

The national inpatient sample was used as data source to identify adults (18 years and older) with a primary discharge diagnosis of epilepsy who were at some point during their hospitalization on cVEEG monitoring. We applied a logistic regression model to identify independent patient-related and hospital/healthcare system-related factors associated with SCA.

RESULTS

A total of weighted 10,059 (0.71 %) patients with epilepsy on cVEEG had a secondary discharge diagnosis of SCA. The main independent factors associated with SCA were the presence of any of the following secondary discharge diagnoses: paroxysmal arrhythmia (OR: 2.29, 95 %CI: 1.96-2.66), myocardial infarction (OR: 3.78, 95 %CI: 2.83-5.05), congestive heart failure (OR: 2.27, 95 %CI: 1.93-2.62), and anoxic brain injury (OR: 57.6, 95 %CI: 50.83-67.27). There was no association between refractory epilepsy and SCA (OR: 0.99, 95 %CI: 0.51-1.93).

CONCLUSION

SCA is a rare event occurring in < 1% of patients with epilepsy undergoing cVEEG monitoring in the United States. Key independent contributors to occurrence of SCA are presence of select cardiovascular conditions and anoxic brain injury.

Obese cardiogenic arrest survivors with significant coronary artery disease had worse in-hospital mortality and neurological outcomes

Cardiogenic arrest is the major cause of sudden cardiac arrest (SCA), accounting for 20% of all deaths annually. The association between obesity and outcomes in cardiac arrest survivors is debatable. However, the effect of obesity on the prognosis of patients with significant coronary artery disease (CAD) successfully resuscitated from cardiogenic arrest is unclear. Thus, the association between body mass index (BMI) and outcomes in cardiogenic arrest survivors with significant CAD was investigated. This multicentre retrospective cohort study recruited 201 patients from January 2011 to September 2017. The eligible cardiogenic arrest survivors were non-traumatic adults who had undergone emergency coronary angiography after sustained return of spontaneous circulation and had significant coronary artery stenosis. BMI was used to classify the patients into underweight, normal-weight, overweight, and obese groups (< 18.5, 18.5–24.9, 25.0–29.9, and ≥ 30 kg/m²; n = 9, 87, 72, and 33, respectively). In-hospital mortality and unsatisfactory neurological outcomes (cerebral performance scale scores = 3–5) were compared among the groups. The obese group presented higher in-hospital mortality and unsatisfactory neurological outcome risks than the normal-weight group (in-hospital mortality: adjusted hazard ratio = 4.27, 95% confidence interval (CI) 1.87–12.04, P = 0.008; unsatisfactory neurological outcomes: adjusted odds ratio = 3.33, 95% CI 1.42–8.78, P = 0.009). Subgroup analysis showed significantly higher in-hospital mortality in the obese patients than in the others in each clinical characteristic. In cardiogenic arrest survivors with significant CAD, obesity was associated with high risks of mortality and unsatisfactory neurological recovery.

An Investigation into the Association Between Inflammatory Bowel Disease and Cardiac Arrhythmias: An Examination of the United States National Inpatient Sample Database

Background:

Inflammatory bowel diseases (IBD) associated-chronic inflammation and autonomic dysregulation may predispose to arrhythmias. However, its exact prevalence is unknown. Thus, we aimed to ascertain the prevalence of arrhythmias in patients with IBD.

Methods:

We queried the Nationwide Inpatient Sample (the largest publicly available all-payer inpatient USA database) from 2012 to 2014. We used the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9 CM) discharge codes to identify adult patients (⩾18 years) with IBD and dysrhythmias (supraventricular tachycardia (SVT), atrial fibrillation, atrial flutter, ventricular tachycardia (VT), or ventricular fibrillation). Furthermore, we identified risk factors for cardiovascular disease. We divided patients into 2 cohorts, IBD cohorts, and non-IBD cohort. The independent effect of a diagnosis of IBD on the risk of dysrhythmias was examined using a multivariable logistic regression model controlling for multiple confounders.

Results:

We identified 847 235 and 84 757 349 weighted hospitalizations among patients with IBD and non-IBD cohorts, respectively. Patients with IBD were less likely to be hospitalized for dysrhythmias than the non-IBD (9.7% vs 14.2%, P < .001). The hospitalization odds for dysrhythmias among patients with IBD were less than the general population (OR 0.87; 95% CI 0.85-0.88). However, the prevalence of SVT and VT was indifferent between the 2 groups. Male sex, age of over 60, and white race were risk factors for dysrhythmias.

Conclusion:

Despite prior reports of a higher prevalence of arrhythmias among patients with IBD, in a nationwide inpatient database, we found lower rates of hospitalization-related-arrhythmias in the IBD population compared to that of the general population.

Insights Into the Spatiotemporal Patterns of Complexity of Ventricular Fibrillation by Multilead Analysis of Body Surface Potential Maps

Background

Ventricular fibrillation (VF) is the main cause of sudden cardiac death, but its mechanisms are still unclear. We propose a noninvasive approach to describe the progression of VF complexity from body surface potential maps (BSPMs).

Methods

We mapped 252 VF episodes (16 ± 10 s) with a 252-electrode vest in 110 patients (89 male, 47 ± 18 years): 50 terminated spontaneously, otherwise by electrical cardioversion (DCC). Changes in complexity were assessed between the onset (“VF start”) and the end (“VF end”) of VF by the nondipolar component index (NDI_BSPM), measuring the fraction of energy nonpreserved by an equivalent 3D dipole from BSPMs. Higher NDI reflected lower VF organization. We also examined other standard body surface markers of VF dynamics, including fibrillatory wave amplitude (A_BSPM), surface cycle length (BsCL_BSPM) and Shannon entropy (ShEn_BSPM). Differences between patients with and without structural heart diseases (SHD, 32 vs. NSHD, 78) were also tested at those stages. Electrocardiographic features were validated with simultaneous endocardium cycle length (CL) in a subset of 30 patients.

Results

All BSPM markers measure an increase in electrical complexity during VF (p < 0.0001), and more significantly in NSHD patients. Complexity is significantly higher at the end of sustained VF episodes requiring DCC. Intraepisode intracardiac CL shortening (VF start 197 ± 24 vs. VF end 169 ± 20 ms; p < 0.0001) correlates with an increase in NDI, and decline in surface CL, f-wave amplitude, and entropy (p < 0.0001). In SHD patients VF is initially more complex than in NSHD patients (NDI_BSPM, p = 0.0007; ShEn_BSPM, p < 0.0001), with moderately slower (BsCL_BSPM, p = 0.06), low-amplitude f-waves (A_BSPM, p < 0.0001). In this population, lower NDI (p = 0.004) and slower surface CL (p = 0.008) at early stage of VF predict self-termination. In the NSHD group, a more abrupt increase in VF complexity is quantified by all BSPM parameters during sustained VF (p < 0.0001), whereas arrhythmia evolution is stable during self-terminating episodes, hinting at additional mechanisms driving VF dynamics.

Conclusion

Multilead BSPM analysis underlines distinct degrees of VF complexity based on substrate characteristics.

Left atrial dysfunction as marker of poor outcome in patients with hypertrophic cardiomyopathy

BACKGROUND

The incremental prognostic value of left atrial (LA) dysfunction, emerging in various clinical contexts, remains poorly explored in hypertrophic cardiomyopathy (HCM).

OBJECTIVE

To assess LA strain correlation with outcome in HCM.

METHODS

A cohort of all 307 consecutive patients presenting with HCM between 2007 and 2017 (54±17 years; 34% women), with comprehensive echocardiography at diagnosis and LA peak longitudinal strain (PALS) and LA peak contraction strain (PACS) measurement, was enrolled and occurrence of HCM related cardiac events analysed.

RESULTS

Clinically, atrial fibrillation (AF) was present in 13%, New York Heart Association functional class II-III in 54%, and B-type natriuretic peptide (BNP) concentration was 199±278pg/mL. By echocardiography, left ventricular (LV) ejection fraction (EF) was 67±10%, LV thickness 21±5mm and European Society of Cardiology HCM risk score 3±3%, with 109 patients (36%) presenting obstructive HCM (LV outflow gradient 21±32mmHg). LA diameter was 41±8mm [with 109 (36%) presenting LA diameter ≥40mm], LA volume index 50±26mL/m², PALS 24±13%, PACS 11±7% and LA peak systolic strain rate (LASRs) 1.7±0.6 s^-1. In addition to AF, age, BNP, LVEF and LV thickness were all independent determinants of lower PALS, with odd ratios almost unchanged after adjustment (all P ≤0.0004). At a mean follow-up of 21 (range 18-23) months, patients with adverse cardiac events (n=65) presented with more impaired LA function (all P ≤0.0005), with a significant association between impaired PALS and worse outcome, hazard ratio 0.94 [95% confidence interval (CI) 0.92-0.97, P<0.0001]. After comprehensive adjustment, PALS remained strongly associated with worse outcome, adjusted hazard ratio 0.86 (95% CI 0.79-0.94; P=0.0008).

CONCLUSIONS

The present study, by gathering a unique HCM cohort, suggests a strong link between LA dysfunction and poor outcome, to be further investigated.

Recommendations for genetic testing in cardiology: Review of major international guidelines

In recent years, the importance of genetic causes of cardiovascular diseases has been increasingly recognized, as the result of significant advances in molecular diagnosis techniques. This growing knowledge has enabled the identification of new phenotypes and the subclassification of clinical syndromes, impacting the therapeutic approach and genetic counseling offered to affected families. This paper describes the state of the art of genetic testing in the main cardiovascular diseases, aiming to provide a useful tool to help cardiologists and other health professionals involved in the care of individuals with hereditary heart diseases and their families.

Artificial intelligence algorithm for predicting cardiac arrest using electrocardiography

BACKGROUND

In-hospital cardiac arrest is a major burden in health care. Although several track-and-trigger systems are used to predict cardiac arrest, they often have unsatisfactory performances. We hypothesized that a deep-learning-based artificial intelligence algorithm (DLA) could effectively predict cardiac arrest using electrocardiography (ECG). We developed and validated a DLA for predicting cardiac arrest using ECG.

METHODS

We conducted a retrospective study that included 47,505 ECGs of 25,672 adult patients admitted to two hospitals, who underwent at least one ECG from October 2016 to September 2019. The endpoint was occurrence of cardiac arrest within 24 h from ECG. Using subgroup analyses in patients who were initially classified as non-event, we confirmed the delayed occurrence of cardiac arrest and unexpected intensive care unit transfer over 14 days.

RESULTS

We used 32,294 ECGs of 10,461 patients and 4483 ECGs of 4483 patients from a hospital were used as development and internal validation data, respectively. Additionally, 10,728 ECGs of 10,728 patients from another hospital were used as external validation data, which confirmed the robustness of the developed DLA. During internal and external validation, the areas under the receiver operating characteristic curves of the DLA in predicting cardiac arrest within 24 h were 0.913 and 0.948, respectively. The high risk group of the DLA showed a significantly higher hazard for delayed cardiac arrest (5.74% vs. 0.33%, P < 0.001) and unexpected intensive care unit transfer (4.23% vs. 0.82%, P < 0.001). A sensitivity map of the DLA displayed the ECG regions used to predict cardiac arrest, with the DLA focused most on the QRS complex.

CONCLUSIONS

Our DLA successfully predicted cardiac arrest using diverse formats of ECG. The results indicate that cardiac arrest could be screened and predicted not only with a conventional 12-lead ECG, but also with a single-lead ECG using a wearable device that employs our DLA.

Effects of empagliflozin versus placebo on cardiac sympathetic activity in acute myocardial infarction patients with type 2 diabetes mellitus: the EMBODY trial

Background

Protection from lethal ventricular arrhythmias leading to sudden cardiac death (SCD) is a crucial challenge after acute myocardial infarction (AMI). Cardiac sympathetic and parasympathetic activity can be noninvasively assessed using heart rate variability (HRV) and heart rate turbulence (HRT). The EMBODY trial was designed to determine whether the Sodium–glucose cotransporter 2 (SGLT2) inhibitor improves cardiac nerve activity.

Methods

This prospective, multicenter, randomized, double-blind, placebo-controlled trial included patients with AMI and type 2 diabetes mellitus (T2DM) in Japan; 105 patients were randomized (1:1) to receive once-daily 10-mg empagliflozin or placebo. The primary endpoints were changes in HRV, e.g., the standard deviation of all 5-min mean normal RR intervals (SDANN) and the low-frequency–to–high-frequency (LF/HF) ratio from baseline to 24 weeks. Secondary endpoints were changes in other sudden cardiac death (SCD) surrogate markers such as HRT.

Results

Overall, 96 patients were included (46, empagliflozin group; 50, placebo group). The changes in SDANN were + 11.6 and + 9.1 ms in the empagliflozin (P = 0.02) and placebo groups (P = 0.06), respectively. Change in LF/HF ratio was – 0.57 and – 0.17 in the empagliflozin (P = 0.01) and placebo groups (P = 0.43), respectively. Significant improvement was noted in HRT only in the empagliflozin group (P = 0.01). Whereas intergroup comparison on HRV and HRT showed no significant difference between the empagliflozin and placebo groups. Compared with the placebo group, the empagliflozin group showed significant decreases in body weight, systolic blood pressure, and uric acid. In the empagliflozin group, no adverse events were observed.

Conclusions

This is the first randomized clinical data to evaluate the effect of empagliflozin on cardiac sympathetic and parasympathetic activity in patients with T2DM and AMI. Early SGLT2 inhibitor administration in AMI patients with T2DM might be effective in improving cardiac nerve activity without any adverse events.

Trial Registration: The EMBODY trial was registered by the UMIN in November 2017 (ID: 000030158). UMIN000030158; https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000034442.

Comparison of different resuscitation methods with regard to injury patterns in cardiac arrest survivors based on computer tomography

PURPOSE

To ensure that patients survive cardiac arrest, cardiopulmonary resuscitation (CPR) is needed. However, the procedure itself can lead to severe injuries. This study aims to examine both possibilities of resuscitation - mechanical or manual - with regard to their risk of injury. To this end, we compare the injuries patterns in both groups of patients after successful resuscitation based on computer tomography (CT).

METHODS

This single-centre retrospective study included 32 patients (female: 21.87 %, male: 78.12 %, Mean age: 60.22 ± 13.93 years) with cardiac arrest followed by successful mechanical CPR, who underwent an early whole-body CT. A control group of 32 patients (female: 21.87 %, male: 78.12 %, mean age: 60.75 ± 13.34 years) that had been resuscitated successfully with manual CPR was matched according to gender and age for a better statistical comparison. Patients with cardiac arrest due to trauma were excluded from the study population.

RESULTS

Mechanically resuscitated patients showed significantly more CPR-related injuries than those who were resuscitated manually (100 % vs. 84.37 %; p = 0.02). In particular, dislocated rib fractures (40.47 vs. 23.80 mean rank, p < 0.01), sternal fractures (74.19 % vs. 25 %; p < 0,01), bleeding complications (29.03 % vs. 3.12 %; p = 0.01), pneumothorax (38.71 % vs. 9.37 %; p = 0.01), mediastinal haematomas (58.01 % vs. 25 %, p = 0.01) and liver lacerations (29.03 % vs. 0 %, p = 0.04) were observed significantly more in patients after mechanical CPR compared to those with manual resuscitation.

CONCLUSIONS

The guideline-based use of mechanical CPR results in a significant increase of internal and musculoskeletal injuries compared to manual CPR.

Secondary prevention of sudden cardiac death

The prevention and treatment of sudden cardiac death (SCD) remains a significant public health challenge. For patients with a history of sudden death attributable to ventricular arrhythmia, implantable cardioverter-defibrillator (ICD) therapy is a mainstay of treatment, although these patients remain at high risk for recurrent ventricular arrhythmia and defibrillator therapies. In this review, we summarize landmark clinical trials evaluating the efficacy of ICD therapy in secondary prevention patients, review clinical outcomes including mode of death in survivors of SCD, and highlight the role for systematic diagnostic evaluation. We additionally discuss the invasive electrophysiological management of these patients, including ICD selection and programming as well as the role and timing of antiarrhythmic drug therapy and catheter ablation. Finally, we frame future challenges and needs to advance the care for secondary prevention patients.

Diabetes and the Risk of Sudden Cardiac Death

PURPOSE OF REVIEW

Persons with diabetes mellitus (DM) have increased morbidity and mortality rates compared with persons without DM. Sudden cardiac death (SCD) is a leading cause of death, and multiple studies have found an increased risk of SCD among individuals with DM. This review sought to collect the latest knowledge of the epidemiological and pathophysiological interplay between DM and SCD.

RECENT FINDINGS

Persons with DM have a two- to tenfold increased risk of SCD compared with persons without DM. The underlying mechanisms for the increased risk of SCD are complex and multifactorial. The main pathophysiological contributors are DM-induced cardiac autonomic neuropathy (CAN), metabolic changes, silent ischemia, and polypharmacy. Persons with DM have an increased risk of SCD. Future studies should focus on CAN and the combined risk of QT prolongation from the interplay between CAN, hypoglycemia, and polypharmacy. Genes and pathways involved in control of the autonomic nervous system and cardiac ion channels could be a future focal point.

Disparities in Premature Cardiac Death Among US Counties From 1999-2017: Temporal Trends and Key Drivers

Background Disparities in premature cardiac death (PCD) might stagnate the progress toward the reduction of PCD in the United States and worldwide. We estimated disparities across US counties in PCD rates and investigated county-level factors related to the disparities. Methods and Results We used US mortality data for cause-of-death and demographic data from death certificates and county-level characteristics data from multiple databases. PCD was defined as any death that occurred at an age between 35 and 74 years with an underlying cause of death caused by cardiac disease based on International Classification of Diseases, Tenth Revision (ICD-10), codes. Of the 1 598 173 PCDs that occurred during 1999-2017, 60.9% were out of hospital. Although the PCD rates declined from 1999-2017, the proportion of out-of-hospital PCDs among all cardiac deaths increased from 58.3% to 61.5%. The geographic disparities in PCD rates across counties widened from 1999 (Theil index=0.10) to 2017 (Theil index=0.23), and within-state differences accounted for the majority of disparities (57.4% in 2017). The disparities in out-of-hospital PCD rates (and in-hospital PCD rates) associated with demographic composition were 36.51% (and 37.51%), socioeconomic features were 18.64% (and 18.36%), healthcare environment were 18.64% (and 13.90%), and population health status were 23.73% (and 30.23%). Conclusions Disparities in PCD rates exist across US counties, which may be related to the decelerated trend of decline in the rates among middle-aged adults. The slower declines in out-of-hospital rates warrants more precision targeting and sustained efforts to ensure progress at better levels of health (with lower PCD rates) against PCD.

Sudden cardiac death in asymptomatic patients with aortic stenosis

OBJECTIVE

We retrospectively analysed outcome data from the Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study to assess the incidence and potential risk factors of sudden cardiac death (SCD) in this prospectively followed cohort of asymptomatic patients with aortic stenosis (AS).

METHODS

Of the 1873 patients included in SEAS, 1849 (99%) with mild to moderate AS (jet velocity 2.5-4.0 m/s at baseline) and available clinical, echocardiographic and follow-up data were analysed. Patients undergoing aortic valve replacement were censored at the time of operation.

RESULTS

During an overall follow-up of 46.1±14.6 months, SCD occurred in 27 asymptomatic patients (1.5%) after a mean of 28.3±16.6 months. The annualised event rate was 0.39%/year. The last follow-up echocardiography prior to the event showed mild to moderate stenosis in 22 and severe stenosis (jet velocity >4 m/s) in 5 victims of SCD. The annualised event rate after the diagnosis of severe stenosis was 0.60%/year compared with 0.46%/year in patients who did not progress to severe stenosis (p=0.79). Patients with SCD were older (p=0.01), had a higher left ventricular mass index (LVMI, p=0.001) and had a lower body mass index (BMI, p=0.02) compared with patients surviving follow-up. Cox regression analysis identified age (HR 1.06, 95% CI 1.01 to 1.11 per year, p=0.02), increased LVMI (HR 1.20, 95% CI 1.10 to 1.32 per 10 g/m², p<0.001) and lower BMI (HR 0.87, 95% CI 0.79 to 0.97 per kg/m², p=0.01) as independent risk factors of SCD.

CONCLUSION

SCD in patients with asymptomatic mild to moderate AS is rare and strongly related to left ventricular hypertrophy but not stenosis severity.

Association of Silent Myocardial Infarction and Sudden Cardiac Death

Importance

Myocardial infarction in the absence of major or unrecognized symptoms are characterized as silent (SMI). The prevalence of SMI among individuals who experience sudden cardiac death (SCD), with or without concomitant electrocardiographic (ECG) changes, has not previously been described in detail from large studies to our knowledge.

Objective

To determine the prevalence of SMI in individuals who experience SCD without a prior diagnosis of coronary artery disease (CAD) and to detect ECG abnormalities associated with SMI-associated SCD.

Design, Setting, and Participants

This case-control study compared autopsy findings, clinical characteristics, and ECG markers associated with SMI in a consecutive cohort of individuals in the Finnish Genetic Study of Arrhythmic Events (Fingesture) study population who were verified to have had SCD. The Fingesture study consists of individuals who had autopsy-verified SCD in Northern Finland between 1998 and 2017. Individuals who had SCD with CAD and evidence of SMI were regarded as having had cases; those who had SCD with CAD without SMI were considered control participants. Analyses of ECG tests were carried out by investigators blinded to the SMI data. Data analysis was completed from October 2018 through November 2018.

Main Outcomes and Measures

Silent MI was defined as a scar detected by macroscopic and microscopic evaluation of myocardium without previously diagnosed CAD. Clinical history was obtained from medical records, previously recorded ECGs, and a standardized questionnaire provided to the next of kin. The hypothesis tested was that SMI would be prevalent in the population who had had SCD with CAD, and it might be detected or suspected from findings on ECGs prior to death in many individuals.

Results

A total of 5869 individuals were included (2459 males [78.8%]; mean [SD] age, 64.9 [12.4] years). The cause of SCD was CAD in 4392 individuals (74.8%), among whom 3122 had no history of previously diagnosed CAD. Two individuals were excluded owing to incomplete autopsy information. An ECG recorded prior to SCD was available in 438 individuals. Silent MI was detected in 1322 individuals (42.4%) who experienced SCD without a clinical history of CAD. The participants with SMI were older than participants without MI scarring (mean [SD] age, 66.9 [11.1] years; 65.5 [11.6] years; P < .001) and were more often men (1102 of 1322 [83.4%] vs 1357 of 1798 [75.5%]; P < .001). Heart weight was higher in participants with SMI (mean [SD] weight, 483 [109] g vs 438 [106] g; P < .001). In participants with SMI, SCD occurred more often during physical activity (241 of 1322 [18.2%] vs 223 of 1798 [12.4%]; P < .001). A prior ECG was abnormal in 125 of the 187 individuals (66.8%) who had SCD after SMI compared with 139 of 251 (55.4%) of those who had SCD without SMI (P = .02).

Conclusions and Relevance

Many individuals who experienced SCD associated with CAD had a previously undetected MI at autopsy. Previous SMI was associated with myocardial hypertrophy and SCD during physical activity. Premortem ECGs in a subset with available data were abnormal in 67% of the individuals who had had a SCD after an SMI.

Diagnostic yield and long-term outcome of nonischemic sudden cardiac arrest survivors and their relatives: Results from a tertiary referral center

BACKGROUND

Cardiac arrest may be the first manifestation of most inherited cardiac diseases. International guidelines recommend screening of relatives of sudden cardiac arrest (SCA) survivors if an inherited cardiac disorder is suspected.

OBJECTIVE

The purpose of this study was to assess the prevalence and spectrum of inherited cardiac diseases and the long-term outcome in a consecutive cohort of nonischemic SCA survivors (probands) and their relatives.

METHODS

This retrospective study consecutively included probands and their relatives referred to our tertiary center for family screening between 2005 and 2018. All participants underwent a systematic workup and follow-up protocol. Data were retrieved from medical records.

RESULTS

We included 155 probands (age 41.2 ± 15.5 years; 61% male) and 282 relatives (age 35.7 ± 18.8 years; 51% male). Mean follow-up was 7.1 years for probands and 4.4 years for relatives. We identified an inherited cardiac disease in 76 (49%) probands and 42 (15%) relatives. An implantable cardioverter-defibrillator was inserted in 147 (95%) probands and 9 (3%) relatives. During follow-up, 4 (3%) probands and 3 (1%) relatives died, and 37 probands and 2 relatives received appropriate shock therapy. All relatives received genetic counseling, and 18 (6%) relatives started pharmacologic treatment during follow-up.

CONCLUSION

Systematic workup of nonischemic SCA survivors and their relatives identified an inherited cardiac disease in 49% of referred probands and 15% of their relatives. The favorable long-term prognosis of diagnosed relatives probably not only reflects lower age but also the effects of early diagnosis, treatment, and follow-up. These findings support systematic workup of SCA survivors and their relatives.

The 10-Year Prognosis and Prevalence of Brugada-Type Electrocardiograms in Elderly Women: A Longitudinal Nationwide Community-Based Prospective Study

BACKGROUND

Brugada syndrome is a disorder associated with sudden cardiac death and characterized by an abnormal electrocardiogram (ECG). Previous studies were predominantly conducted in men, and the data on long-term prognosis are limited. Information about women, especially elderly women, is lacking.

OBJECTIVE

The aim of this study was to investigate the long-term prognosis of the Brugada ECG pattern in elderly women.

METHOD

We investigated the 10-year prognosis of the Brugada ECG pattern in elderly women in a nationwide community-based population in Taiwan. Community-dwelling women older than 55 years were prospectively recruited from December 2008 to March 2013 by a stratified random sampling method. All enrolled individuals were followed up annually until April 2019, and the cause of death was documented by citizen death records.

RESULTS

Among 2597 women, 60 (2.31%) had a Brugada-type ECG, and this prevalence was higher than the mean global prevalence of 0.23%. One woman had a type 1 ECG (0.04%), whereas 15 (0.58%) and 44 (1.70%) women had type 2 and type 3 ECG patterns, respectively. Cox survival analysis revealed that all-cause mortality and cardiac mortality were similar in the individuals with and without a Brugada-type ECG during a mean follow-up of 96.1 ± 20.5 months.

CONCLUSIONS

Our findings suggest that Brugada ECG patterns are not infrequent in elderly women but are not associated with increased risk of mortality in long-term follow-up; these findings may help reduce unnecessary anxiety for physicians, nurses, allied health caregivers, and patients.

Development a clinical prediction model of the neurological outcome for patients with coma and survived 24 hours after cardiopulmonary resuscitation

Background

Cardiac arrest is still a global public health problem at present. The neurological outcome is the core indicator of the prognosis of cardiac arrest. However, there is no effective means or tools to predict the neurological outcome of patients with coma and survived 24 hours after successful cardiopulmonary resuscitation (CPR).

Hypothesis

Therefore, we expect to construct a prediction model to predict the neurological outcome for patients with coma and survived 24 hours after successful CPR.

Methods

A retrospective cohort study was used to construct a prediction model of the neurological function for patients with coma and survived 24 hours after successful CPR. From January 2007 to December 2015, a total of 262 patients met the inclusion and exclusion criteria.

Results

The predictive model was developed using preselected variables by a systematic review of the literature. Finally, we get five sets of models (three sets of construction models and two sets of internal verification models) which with similar predictive value. The stepwise model, which including seven variables (age, noncardiac etiology, nonshockable rhythm, bystander CPR, total epinephrine dose, APTT, and SOFA score), was the simplest model, so we choose it as our final predictive model. The area under the ROC curve (AUC), specificity, and sensitivity of the stepwise model were respectively 0.82 (0.77, 0.87), 0.72and 0.82. The AUC, specificity, and sensitivity of the bootstrap stepwise (BS stepwise) model were respectively 0.82 (0.77, 0.87), 0.71, and 0.82.

Conclusion

This new and validated predictive model may provide individualized estimates of neurological function for patients with coma and survived 24 hours after successful CPR using readily obtained clinical risk factors. External validation studies are required further to demonstrate the model's accuracy in diverse patient populations.

Association between an indel polymorphism within CTH and the risk of sudden cardiac death in a Chinese population

Individuals harbouring specific genetic variations might trend towards suffering sudden cardiac death. Cystathionine-γ-lyase is one of the key enzymes of endogenous hydrogen sulfide production, and a key factor on the expression regulation of hydrogen sulfide in human heart. Compelling studies have suggested the cardioprotective effects of hydrogen sulfide, while it remains controversial whether cystathionine-γ-lyase and hydrogen sulfide are beneficial to cardiovascular diseases. In this study, we performed a candidate-gene-based study to evaluate the association of the Indel polymorphism rs113044851 within the 3' untranslated region of Cystathionine-γ-lyase gene and risk of sudden cardiac death in a Chinese Han population. Logistic regression analysis showed that the insertion allele of rs113044851 significantly decreased the risk of sudden cardiac death [odds ratio = 0.58; 95% confidence interval:0.38-0.88; P = 0.0076]. Further genotype-phenotype association analysis indicated that the insertion allele was significantly associated with lower expression of cystathionine-γ-lyase in myocardium tissues. The subsequently in-silico predication revealed that compared with the deletion allele, the binding of the insertion allele with miR-1324 matched better. Finally, dual-luciferase activity assay validated the prediction that the gene transcriptional activity indicated by firefly luciferase activity with ins/ins genotype was lower than that with del/del genotype. In summary, our data suggested that rs113044851 might contribute to susceptibility of sudden cardiac death via regulating gene expression at post-transcriptional level. This indel has the potential to become a molecular diagnosis marker and genetic counseling of sudden cardiac death.

Ventricular arrhythmias and ARNI: is it time to reappraise their management in the light of new evidence?

The remarkable scientific progress in the treatment of patients with heart failure (HF) and reduced ejection fraction (HFrEF) has more than halved the risk of sudden cardiac death (SCD) in this setting. However, SCD remains one of the major causes of death in this patient population. Beyond the acknowledged role of beta blockers and inhibitors of the renin-angiotensin-aldosterone system (RAAS), a new class of drugs, the angiotensin receptor neprilysin inhibitors (ARNI), proved to reduce the overall cardiovascular mortality and, more specifically, the risk of SCD in HFrEF patients. The mechanism by which ARNI may reduce the mortality connected with harmful ventricular arrhythmias is not utterly clear. A variety of direct and indirect mechanisms have been suggested, but a favorable left ventricular reverse remodeling seems to play a key role in this setting. Furthermore, the well-known protective effect of implantable cardioverter-defibrillator (ICD) has been debated in HFrEF patients with non-ischemic cardiomyopathy (NICM) arguing against the role of primary prevention ICD in this setting, particularly when ARNI therapy is considered. The purpose of this review was to provide insights into the SCD mechanisms involved in HFrEF patients together with the current role of electrical therapies and new drug agents in this setting. Graphical abstract.

Improving Clinical Translation of Machine Learning Approaches Through Clinician-Tailored Visual Displays of Black Box Algorithms: Development and Validation

BACKGROUND

Despite the promise of machine learning (ML) to inform individualized medical care, the clinical utility of ML in medicine has been limited by the minimal interpretability and black box nature of these algorithms.

OBJECTIVE

The study aimed to demonstrate a general and simple framework for generating clinically relevant and interpretable visualizations of black box predictions to aid in the clinical translation of ML.

METHODS

To obtain improved transparency of ML, simplified models and visual displays can be generated using common methods from clinical practice such as decision trees and effect plots. We illustrated the approach based on postprocessing of ML predictions, in this case random forest predictions, and applied the method to data from the Left Ventricular (LV) Structural Predictors of Sudden Cardiac Death (SCD) Registry for individualized risk prediction of SCD, a leading cause of death.

RESULTS

With the LV Structural Predictors of SCD Registry data, SCD risk predictions are obtained from a random forest algorithm that identifies the most important predictors, nonlinearities, and interactions among a large number of variables while naturally accounting for missing data. The black box predictions are postprocessed using classification and regression trees into a clinically relevant and interpretable visualization. The method also quantifies the relative importance of an individual or a combination of predictors. Several risk factors (heart failure hospitalization, cardiac magnetic resonance imaging indices, and serum concentration of systemic inflammation) can be clearly visualized as branch points of a decision tree to discriminate between low-, intermediate-, and high-risk patients.

CONCLUSIONS

Through a clinically important example, we illustrate a general and simple approach to increase the clinical translation of ML through clinician-tailored visual displays of results from black box algorithms. We illustrate this general model-agnostic framework by applying it to SCD risk prediction. Although we illustrate the methods using SCD prediction with random forest, the methods presented are applicable more broadly to improving the clinical translation of ML, regardless of the specific ML algorithm or clinical application. As any trained predictive model can be summarized in this manner to a prespecified level of precision, we encourage the use of simplified visual displays as an adjunct to the complex predictive model. Overall, this framework can allow clinicians to peek inside the black box and develop a deeper understanding of the most important features from a model to gain trust in the predictions and confidence in applying them to clinical care.

Common Genetic Variants Modulate the Electrocardiographic Tpeak-to-Tend Interval

Sudden cardiac death is responsible for half of all deaths from cardiovascular disease. The analysis of the electrophysiological substrate for arrhythmias is crucial for optimal risk stratification. A prolonged T-peak-to-Tend (Tpe) interval on the electrocardiogram is an independent predictor of increased arrhythmic risk, and Tpe changes with heart rate are even stronger predictors. However, our understanding of the electrophysiological mechanisms supporting these risk factors is limited. We conducted genome-wide association studies (GWASs) for resting Tpe and Tpe response to exercise and recovery in ∼30,000 individuals, followed by replication in independent samples (∼42,000 for resting Tpe and ∼22,000 for Tpe response to exercise and recovery), all from UK Biobank. Fifteen and one single-nucleotide variants for resting Tpe and Tpe response to exercise, respectively, were formally replicated. In a full dataset GWAS, 13 further loci for resting Tpe, 1 for Tpe response to exercise and 1 for Tpe response to exercise were genome-wide significant (p ≤ 5 × 10^-8). Sex-specific analyses indicated seven additional loci. In total, we identify 32 loci for resting Tpe, 3 for Tpe response to exercise and 3 for Tpe response to recovery modulating ventricular repolarization, as well as cardiac conduction and contraction. Our findings shed light on the genetic basis of resting Tpe and Tpe response to exercise and recovery, unveiling plausible candidate genes and biological mechanisms underlying ventricular excitability.