The spectrum of epidemiology underlying sudden cardiac death

Brugada Syndrome as a Major Cause of Sudden Cardiac Death in Asians

Brugada syndrome (BrS) is one of the main inherited arrhythmia syndromes causing ventricular fibrillation (VF) and sudden cardiac death in young to middle-aged men, especially in Asians. The diagnosis of BrS is based on spontaneous or drug-provoked type 1 Brugada electrocardiogram. The current reliable therapy for BrS patients with VF history is the implantation of an implantable cardioverter-defibrillator. As for BrS patients without VF history, how asymptomatic BrS patients should effectively be treated is still uncertain because risk stratification of the BrS is still inadequate. Various parameters and combinations of several parameters have been reported for risk stratification of BrS. The SCN5A gene is believed to be the only gene that is responsible for BrS, and it has been reported to be useful for risk stratification. This review focuses on risk stratification of BrS patients, and focuses specifically on BrS patients of Asian descent.

Pleiotropic Benefits of Statins in Cardiovascular Diseases

In 1976, Japanese microbiologist Akira Endo discovered the first statin as a product of the fungus Penicillium citrinum that inhibited the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase. Their primary mode of action is to lower the blood cholesterol by decreasing hepatic cholesterol production, which upregulates hepatic low-density lipoprotein (LDL) receptors and increases LDL-cholesterol clearance. In addition to cholesterol lowering, statins inhibit other downstream products of the mevalonate pathway, causing the so-called pleiotropic effects. As a result of their pleiotropic effects statins modulate virtually all known processes of atherosclerosis and have beneficial effects outside the cardiovascular system Statins inhibit the post-translational prenylation of small GTP-binding proteins such as Rho, Rac, as well as their downstream effectors such as Rho kinase and nicotinamide adenine dinucleotide phosphate oxidases since they suppress the synthesis of isoprenoid intermediates in the cholesterol biosynthetic pathway altering the expression of endothelial nitric oxide synthase, the stability of atherosclerotic plaques, production of proinflammatory cytokines, reactive oxygen species, platelet reactivity, development of cardiac hypertrophy and fibrosis in cell culture and animal experiments. Inhibition of Rho and Rho-associated coiled-coil containing protein kinase (ROCK), has emerged as the principle mechanisms underlying the pleiotropic effects of statins. However, the relative contributions of statin pleiotropy to clinical outcomes are debatable and difficult to measure because the amount of isoprenoid inhibition by statins corresponds to some extent with the amount of LDL-cholesterol decrease. This article examines some of the existing molecular explanations underlying statin pleiotropy and discusses if they have clinical relevance in cardiovascular diseases.

Deep-Learning-Based Estimation of the Spatial QRS-T Angle from Reduced-Lead ECGs

The spatial QRS-T angle is a promising health indicator for risk stratification of sudden cardiac death (SCD). Thus far, the angle is estimated solely from 12-lead electrocardiogram (ECG) systems uncomfortable for ambulatory monitoring. Methods to estimate QRS-T angles from reduced-lead ECGs registered with consumer healthcare devices would, therefore, facilitate ambulatory monitoring. (1) Objective: Develop a method to estimate spatial QRS-T angles from reduced-lead ECGs. (2) Approach: We designed a deep learning model to locate the QRS and T wave vectors necessary for computing the QRS-T angle. We implemented an original loss function to guide the model in the 3D space to search for each vector's coordinates. A gradual reduction of ECG leads from the largest publicly available dataset of clinical 12-lead ECG recordings (PTB-XL) is used for training and validation. (3) Results: The spatial QRS-T angle can be estimated from leads {I, II, aVF, V2} with sufficient accuracy (absolute mean and median errors of 11.4° and 7.3°) for detecting abnormal angles without sacrificing patient comfortability. (4) Significance: Our model could enable ambulatory monitoring of spatial QRS-T angles using patch- or textile-based ECG devices. Populations at risk of SCD, like chronic cardiac and kidney disease patients, might benefit from this technology.

TRPM4 inhibition by meclofenamate suppresses Ca2+-dependent triggered arrhythmias

AIMS

Cardiac arrhythmias are a major factor in the occurrence of morbidity and sudden death in patients with cardiovascular disease. Disturbances of Ca2+ homeostasis in the heart contribute to the initiation and maintenance of cardiac arrhythmias. Extrasystolic increases in intracellular Ca2+ lead to delayed afterdepolarizations and triggered activity, which can result in heart rhythm abnormalities. It is being suggested that the Ca2+-activated nonselective cation channel TRPM4 is involved in the aetiology of triggered activity, but the exact contribution and in vivo significance are still unclear.

METHODS AND RESULTS

In vitro electrophysiological and calcium imaging technique as well as in vivo intracardiac and telemetric electrocardiogram measurements in physiological and pathophysiological conditions were performed. In two distinct Ca2+-dependent proarrhythmic models, freely moving Trpm4-/- mice displayed a reduced burden of cardiac arrhythmias. Looking further into the specific contribution of TRPM4 to the cellular mechanism of arrhythmias, TRPM4 was found to contribute to a long-lasting Ca2+ overload-induced background current, thereby regulating cell excitability in Ca2+ overload conditions. To expand these results, a compound screening revealed meclofenamate as a potent antagonist of TRPM4. In line with the findings from Trpm4-/- mice, 10 µM meclofenamate inhibited the Ca2+ overload-induced background current in ventricular cardiomyocytes and 15 mg/kg meclofenamate suppressed catecholaminergic polymorphic ventricular tachycardia-associated arrhythmias in a TRPM4-dependent manner.

CONCLUSION

The presented data establish that TRPM4 represents a novel target in the prevention and treatment of Ca2+-dependent triggered arrhythmias.

Risk Factors for Sudden Death in Athletes, Is There a Role for Screening?

Purpose of Review

Sudden cardiac death (SCD) in a young athlete is an infrequent yet devastating event often associated with substantial media attention. Screening athletes for conditions associated with SCD is a controversial topic with debate surrounding virtually each component including the ideal subject, method, and performer/interpreter of such screens. In fact, major medical societies such as the American College of Cardiology/American Heart Association and the European Society of Cardiology have discrepant recommendations on the matter, and major sporting associations have enacted a wide range of screening policies, highlighting the confusion on this subject. This review seeks to summarize the literature in this area to address the complex and disputed subject of screening young athletes for SCD.

Recent Findings

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause myocarditis, which is one acquired cardiac disease associated with SCD. The coronavirus 2019 (COVID-19) pandemic has therefore resulted in an increased incidence of an otherwise less common condition, providing an expanded dataset for further study of this condition. Recent findings indicate that cardiac complications of athletes with myocardial involvement of SARS-CoV-2 infection are rare. Other contemporary work in SCD screening has been focused on the implementation of various screening protocols and measuring their effectiveness.

Summary

No universal consensus exists for athlete screening for conditions associated with SCD with varying guidelines and protocols across cardiology and sport-specific organizations. No screening program will prevent all SCD; however, small programs managed by physicians familiar with the examination of an athlete that carefully personalize screening to the individual may maximize detection of dangerous cardiac conditions while minimizing false positives.

Characterizing arrhythmia using machine learning analysis of Ca2+ cycling in human cardiomyocytes

Accurate modeling of the heart electrophysiology to predict arrhythmia susceptibility remains a challenge. Current electrophysiological analyses are hypothesis-driven models drawing conclusions from changes in a small subset of electrophysiological parameters because of the difficulty of handling and understanding large datasets. Thus, we develop a framework to train machine learning classifiers to distinguish between healthy and arrhythmic cardiomyocytes using their calcium cycling properties. By training machine learning classifiers on a generated dataset containing a total of 3,003 healthy derived cardiomyocytes and their various arrhythmic states, the multi-class models achieved >90% accuracy in predicting arrhythmia presence and type. We also demonstrate that a binary classifier trained to distinguish cardiotoxic arrhythmia from healthy electrophysiology could determine the key biological changes associated with that specific arrhythmia. Therefore, machine learning algorithms can be used to characterize underlying arrhythmic patterns in samples to improve in vitro preclinical models and complement current in vivo systems.

•

Calcium reporter enabled analysis of hPSC-derived CM electrophysiology

•

Calcium electrophysiology can be decomposed to train machine learning classifiers

•

Multi-class classifier distinguishes different forms of arrhythmias

•

Binary-class classifiers identify key electrophysiological changes a priori

Physical demands and physiological strain of American football referees while officiating

OBJECTIVES

Certain occupations are associated with greater risk of triggering a sudden cardiac event because of high levels of physical exertion and extreme thermal environments in which they occur. The extent to which sports officials--particularly high school (HS) American football referees--experience these conditions is unknown. Forty-six male HS officials (72% White/Caucasian; age = 48 ± 12 years, body mass index = 31.7 ± 6.6 kg·m^-2) were studied to quantify the physiological strain and physical demands of officiating.

METHODS

Referee demographics (e.g., experience, habitual exercise), pre-game urine specific gravity (U_SG), thermal (peak core temperature [T_core]) and cardiovascular (average heart rate [HR]) strain, kinematic activity (e.g., total distance, speed, mechanical intensity), and environmental conditions were measured during 10 regular season varsity HS football games (≈2.5 h each) in the Southeastern United States (average wet bulb globe temperature and relative humidity: 18.9 ± 6.0 °C and 78.2% ± 12.1%). Analyses included descriptive statistics, bivariate correlations, and linear regression.

RESULTS

Referees covered 5.2 ± 1.2 km per game, eliciting average HR and peak T_core of 71.5% ± 8.0% HR_max and 38.3 ± 0.5 °C, respectively; 38% began games dehydrated (U_SG = 1.026 ± 0.004). Multiple regression analyses revealed that obesity (β = 0.34), not participating in regular exercise (β = -0.36), and officiating at lower mechanical intensity (β = -0.33) predicted greater cardiovascular strain (all p ≤ 0.03). White/Caucasian race/ethnicity (β = 0.59), younger age (β = -0.46), and obesity (β = 0.28) predicted greater thermal strain (all p ≤ 0.01).

CONCLUSION

HS football referees experienced elevated levels of physiological strain while officiating, with individual factors modulating the magnitude of strain. Strategies aimed at reducing obesity, increasing exercise participation, and improving cardiovascular health should be emphasized to mitigate strain and prevent cardiac events.

German Cardiac Arrest Registry: rationale and design of G-CAR

BACKGROUND

In Germany, 70,000-100,000 persons per year suffer from out-of-hospital cardiac arrest (OHCA). Despite medical progress, survival rates with good neurological outcome remain low. For many important clinical issues, no or only insufficient evidence from randomised trials is available. Therefore, a systemic and standardised acquisition of the treatment course and of the outcome of OHCA patients is warranted.

STUDY DESIGN

The German Cardiac Arrest Registry (G-CAR) is an observational, prospective, multicentre registry. It will determine the characteristics, initial treatment strategies, invasive procedures, revascularisation therapies and the use of mechanical circulatory support devices with a focus on extracorporeal cardiopulmonary resuscitation. A special feature is the prospective 12-month follow-up evaluating mortality, neurological outcomes and several patient-reported outcomes in the psychosocial domain (health-related quality of life, cognitive impairment, depression/anxiety, post-traumatic stress disorder and social reintegration). In a pilot phase of 24 months, 15 centres will include approximately 400 consecutive OHCA patients ≥ 18 years. Parallel to and after the pilot phase, scaling up of G-CAR to a national level is envisaged.

CONCLUSION

G-CAR is the first national registry including a long-term follow-up for adult OHCA patients. Primary aim is a better understanding of the determinants of acute and long-term outcomes with the perspective of an optimised treatment.

TRIAL REGISTRY

NCT05142124. German Cardiac Arrest Registry (G-CAR).

Carbamazepine Increases the Risk of Sudden Cardiac Arrest by a Reduction of the Cardiac Sodium Current

Aim: To assess the risk of sudden cardiac arrest (SCA) associated with the use of carbamazepine (CBZ) and establish the possible underlying cellular electrophysiological mechanisms.

Methods: The SCA risk association with CBZ was studied in general population cohorts using a case–control design (n = 5,473 SCA cases, 21,866 non-SCA controls). Effects of 1–100 µM CBZ on action potentials (APs) and individual membrane currents were determined in isolated rabbit and human cardiomyocytes using the patch clamp technique.

Results: CBZ use was associated with increased risk of SCA compared with no use (adjusted odds ratio 1.90 [95% confidence interval: 1.12–3.24]). CBZ reduced the AP upstroke velocity of rabbit and human cardiomyocytes, without prominent changes in other AP parameters. The reduction occurred at ≥30 µM and was frequency-dependent with a more pronounced reduction at high stimulus frequencies. The cardiac sodium current (I_Na) was reduced at ≥30 μM; this was accompanied by a hyperpolarizing shift in the voltage-dependency of inactivation. The recovery from inactivation was slower, which is consistent with the more pronounced AP upstroke velocity reduction at high stimulus frequencies. The main cardiac K⁺ and Ca²⁺ currents were unaffected, except reduction of L-type Ca²⁺ current by 100 µM CBZ.

Conclusion: CBZ use is associated with an increased risk of SCA in the general population. At concentrations of 30 µM and above, CBZ reduces AP upstroke velocity and I_Na in cardiomyocytes. Since the concentration of 30 µM is well within the therapeutic range (20–40 µM), we conclude that CBZ increases the risk of SCA by a reduction of the cardiac I_Na.

Risk of out-of-hospital cardiac arrest in patients with rheumatoid arthritis: a nationwide study

Aim

Inflammatory cytokines in patients with rheumatoid arthritis (RA) directly affect cardiac electrophysiology by inhibiting cardiac potassium currents, leading to delay of cardiac repolarisation and QT-prolongation. This may result in lethal arrhythmias. We studied whether RA increases the rate of out-of-hospital cardiac arrest (OHCA) in the general population.

Methods

We conducted a nested case–control in a cohort of individuals between 1 June 2001 and 31 December 2015. Cases were OHCA patients from presumed cardiac causes, and were matched with non-OHCA-controls based on age, sex and OHCA date. Cox-regression with time-dependent covariates was conducted to assess the association between RA and OHCA by calculating the HR and 95% CI. Stratified analyses were performed according to sex and presence of cardiovascular diseases. Also, the association between OHCA and use of non-steroidal anti-inflammatory drugs (NSAIDs) in patients with RA was studied.

Results

We included 35 195 OHCA cases of whom 512 (1.45%) had RA, and 351 950 non-OHCA controls of whom 3867 (1.10%) had RA. We found that RA was associated with increased rate of OHCA after adjustment for cardiovascular comorbidities and use of QT-prolonging drugs (HR: 1.22, 95% CI: 1.11 to 1.34). Stratification by sex revealed that increased OHCA rate occurred in women (HR: 1.32, 95% CI: 1.16 to 1.50) but not in men (HR: 1.12, 95% CI: 0.97 to 1.28; P value interaction=0.046). OHCA rate of RA was not further increased in patients with cardiovascular disease. Finally, in patients with RA, use of NSAIDs was not associated with OHCA.

Conclusion

In the general population, RA is associated with increased rate of OHCA in women but not in men.

Role of circular RNA in myocardial ischemia and ageing-related diseases

Circular RNA (circRNA) is a new endogenous transcription product, which has attracted significant attention in RNA biology research.CircRNA comprise exons or introns involved in regulation of various mechanisms.These molecules are stable and species-specific, as well as cell and tissue-specific.Cardiovascular diseases particularly myocardial ischemia and ageing-related diseases, pose a major health care burden and novel treatments and biomarkers should be explored.Recent findings indicate that circRNAs are implicated in biological processes, such as glucose metabolism, fatty acid oxidation, mitochondrial biosynthesis, implying that they are potential targets for myocardial ischemia treatment.In the present review, the functions of circRNAs in the heart are described, with emphasis given on in the relationship with myocardial ischemia and cardiac aging-related diseases.Directions for future research are also summarized.

Latent Causes of Sudden Cardiac Arrest

Inherited arrhythmia syndromes are a common cause of apparently unexplained cardiac arrest or sudden cardiac death. These include long QT syndrome and Brugada syndrome, with a well-recognized phenotype in most patients with sufficiently severe disease to lead to cardiac arrest. Less common and typically less apparent conditions that may not be readily evident include catecholaminergic polymorphic ventricular tachycardia, short QT syndrome and early repolarization syndrome. In cardiac arrest patients whose extensive testing does not reveal an underlying etiology, a diagnosis of idiopathic ventricular fibrillation or short-coupled ventricular fibrillation is assigned. This review summarizes our current understanding of the less common inherited arrhythmia syndromes and provides clinicians with a practical approach to diagnosis and management.

Burden of influenza in adults with cardiac arrest admissions in Australia

BACKGROUND

Cardiac arrest is the least preventable burden of cardiovascular disease, as treatment depends on timely resuscitation. The incidence of sudden cardiac arrest (SCA) is high, contributing 10-20% of cardiovascular mortality globally. The influenza vaccine reduces the risk of acute cardiovascular events. Little is known about the relationship of influenza infection to cardiac arrest.

METHODS

This study aimed to determine the estimated rate of SCA hospitalisations attributable to influenza in Australian adults. A generalised-additive statistical model was applied in the study. Weekly counts of laboratory-confirmed influenza notifications were used as independent variables in the model.

RESULTS

Our estimates showed that the yearly rate of SCA hospitalisations varied, and a significant association with influenza was observed in some years in older adults aged 65 years and over. On average, the annual estimated SCA hospitalisations rate due to influenza in adults aged 50-64 years and ≥ 65 years were 0.7 (95%CI: 0.4, 1.1) and 5.3 (95%CI: 4.4, 6.2) per 100,000 population, respectively.

CONCLUSION

The association between influenza and SCA is evident in adults and the disease burden is significant in older people. Prevention of influenza by vaccination may reduce SCA.

The Risk of Sudden Cardiac Death Associated with QRS, QTc and JTc intervals in the General Population Revision #4

BACKGROUND

QRS duration and QTc interval have been associated with sudden cardiac death (SCD), but no data is available on the significance of repolarization component (JTc interval) of QTc as an independent risk marker in the general population.

OBJECTIVE

In this study, we sought to quantify the risk of SCD associated with QRS, QTc and JTc.

METHODS

This study was conducted using data from 3 population cohorts from different eras, comprising a total of 20,058 individuals. The follow-up was limited to 10 years and age at baseline to 30-61 years. QRS duration and QT interval (Bazett's) were measured from standard 12-lead electrocardiograms at baseline. JTc interval was defined as QTc - QRS duration. Cox proportional hazard models that controlled for confounding clinical factors identified at baseline were used to estimate the relative risk of SCD.

RESULTS

During a mean period of 9.7 years, 207 SCDs occurred (1.1 per 1000 person-years). QRS duration was associated with a significantly increased risk of SCD in each cohort (pooled hazard ratio 1.030 per 1 ms increase (95% confidence interval 1.017-1.043). The QTc interval had borderline to significant associations with SCD and varied among cohorts (pooled HR 1.007, 95%CI 1.001-1.012). JTc interval as a continuous variable was not associated with SCD (pooled HR 1.001, 95%CI 0.996-1.007).

CONCLUSIONS

Prolonged QRS durations and QTc intervals are associated with an increased risk of sudden cardiac death. However, when QTc is deconstructed into QRS and JTc intervals, the repolarization component (JTc) appears to have no independent prognostic value.

Anger recall mental stress decreases 123I-metaiodobenzylguanidine (123I-MIBG) uptake and increases heterogeneity of cardiac sympathetic activity in the myocardium in patients with ischemic cardiomyopathy

BACKGROUND

Acute psychological stressors such as anger can precipitate ventricular arrhythmias, but the mechanism is incompletely understood. Quantification of regional myocardial sympathetic activity with 123I-metaiodobenzylguanidine (123I-mIBG) SPECT imaging in conjunction with perfusion imaging during mental stress may identify a mismatch between perfusion and sympathetic activity that may exacerbate a mismatch between perfusion and sympathetic activity that could create a milieu of increased vulnerability to ventricular arrhythmia.

METHODS

Five men with ischemic cardiomyopathy (ICM), and five age-matched healthy male controls underwent serial 123I-mIBG and 99mTc-Tetrofosmin SPECT/CT imaging during an anger recall mental stress task and dual isotope imaging was repeated approximately 1 week later during rest. Images were reconstructed using an iterative reconstruction algorithm with CT-based attenuation correction. The mismatch of left ventricular myocardial 123I-mIBG and 99mTc-Tetrofosmin was assessed along with radiotracer heterogeneity and the 123I-mIBG heart-to-mediastinal ratios (HMR) were calculated using custom software developed at Yale.

RESULTS

The hemodynamic response to mental stress was similar in both groups. The resting-HMR was greater in healthy control subjects (3.67 ± 0.95) than those with ICM (3.18 ± 0.68, P = .04). Anger recall significantly decreased the HMR in ICM patients (2.62 ± 0.3, P = .04), but not in normal subjects. The heterogeneity of 123I-mIBG uptake in the myocardium was significantly increased in ICM patients during mental stress (26% ± 8.23% vs. rest: 19.62% ± 9.56%; P = .01), whereas the 99mTc-Tetrofosmin uptake pattern was unchanged.

CONCLUSION

Mental stress decreased the 123I-mIBG HMR, increased mismatch between sympathetic activity and myocardial perfusion, and increased the heterogeneity of 123I-mIBG uptake in ICM patients, while there was no significant change in myocardial defect size or the heterogeneity of 99mTc-Tetrofosmin perfusion. The changes observed in this proof-of-concept study may provide valuable information about the trigger-substrate interaction and the potential vulnerability for ventricular arrhythmias.

Sudden cardiac death in heart failure with preserved ejection fraction: an updated review

Despite the advances in medical and device therapies for heart failure (HF), sudden cardiac death (SCD) remains a tremendous global burden in patients with HF. Among the risk factors for SCD, HF has the greatest impact. Previous studies focusing on patients with systolic dysfunction have found several predictive factors associated with SCD, leading to the subsequent development of strategies of primary prevention, like placement of implantable cardioverter-defibrillator (ICD) in high-risk patients. Although patients with HF with preserved ejection fraction (HFpEF) were less prone to SCD compared to patients with HF with reduced ejection fraction (HFrEF), patients with HFpEF did account for a significant proportion of all HF patients who encountered SCD. The cutoff value of left ventricular ejection fraction (LVEF) to define the subset of HF did not reach consensus until 2016 when the European Society of Cardiology proposed a new classification system by LVEF. There is a great unmet need in the field of SCD in HFpEF regarding risk stratification and appropriate device therapy with ICD implantation. In this article, we will approach SCD in HFpEF from HFrEF subsets. We also aim at clarifying the mechanisms, risk factors, and prevention of SCD in HFpEF.

Arrhythmic sudden death survival prediction using deep learning analysis of scarring in the heart

Sudden cardiac death from arrhythmia is a major cause of mortality worldwide. Here, we develop a novel deep learning (DL) approach that blends neural networks and survival analysis to predict patient-specific survival curves from contrast-enhanced cardiac magnetic resonance images and clinical covariates for patients with ischemic heart disease. The DL-predicted survival curves offer accurate predictions at times up to 10 years and allow for estimation of uncertainty in predictions. The performance of this learning architecture was evaluated on multi-center internal validation data and tested on an independent test set, achieving concordance index of 0.83 and 0.74, and 10-year integrated Brier score of 0.12 and 0.14. We demonstrate that our DL approach with only raw cardiac images as input outperforms standard survival models constructed using clinical covariates. This technology has the potential to transform clinical decision-making by offering accurate and generalizable predictions of patient-specific survival probabilities of arrhythmic death over time.

New diagnostic and therapeutic strategies for myocardial infarction via nanomaterials

Myocardial infarction is lethal to patients because of insufficient blood perfusion to vital organs. Several attempts have been made to improve its prognosis, among which nanomaterial research offers an opportunity to address this problem at the molecular level and has the potential to improve disease prevention, diagnosis, and treatment significantly. Up to now, nanomaterial-based technology has played a crucial role in broad novel diagnostic and therapeutic strategies for cardiac repair. This review summarizes various nanomaterial applications in myocardial infarction from multiple aspects, including high precision detection, pro-angiogenesis, regulating immune homeostasis, and miRNA and stem cell delivery vehicles. We also propose promising research hotspots that have not been reported much yet, such as conjugating pro-angiogenetic elements with nanoparticles to construct drug carriers, developing nanodrugs targeting other immune cells except for macrophages in the infarcted myocardium or the remote region. Though most of those strategies are preclinical and lack clinical trials, there is tremendous potential for their further applications in the future.

Trends and associated factors in place of death among individuals with cardiovascular disease in China, 2008-2020: A population-based study

Background

Cardiovascular disease (CVD) is the leading cause of death (COD) in China. Understanding the characteristics of place of death (POD) among CVD deaths would be of great importance to evaluate the healthcare service utilization at the end stage of life. Limited studies have reported the POD distribution among CVD deaths, and little was known about the associated factors of hospital CVD deaths.

Methods

By using data from National Mortality Surveillance System (NMSS) in China, this study presented the characteristics of POD distribution during 2008 and 2020. Afterwards, multilevel logistic regression was used to explore associated factors of hospital CVD deaths and quantify the magnitude to which the spatial variations of hospital CVD deaths could be explained by those associated factors.

Findings

During 2008-2020, there was 7101871 CVD deaths collected by NMSS in China, with 77·13% home deaths and 18·49% hospital deaths. Shanghai (59·40%) had the highest percentage of hospital CVD deaths. Age, sex, ethnicity, marital status, education, occupation, underlying COD were significant influential factors of hospital CVD deaths. Spatial variations were shown at provincial level, with 33·88% of them being explained by factors at individual level.

Interpretation

Home was the leading POD among CVD deaths in China, those CVD decedents characterized as the female, the youngest, Han population, the married, the retiree, lived in urban areas, with higher socioeconomic status and died of chronic CVDs had a higher probability of hospital deaths. Providing accessible and available healthcare services were priorities to improve quality of end-of-life care, significant variations among provinces and sub-population also reminded us of the requirements for equal healthcare resources allocation and multiple options for minorities of POD preference at the end stage of life.

Funding

National Key Research & Development Program of China (grant number 2018YFC1315301)

Clinical Phenotypes of Cardiovascular and Heart Failure Diseases Can Be Reversed? The Holistic Principle of Systems Biology in Multifaceted Heart Diseases

Recent advances in cardiology and biological sciences have improved quality of life in patients with complex cardiovascular diseases (CVDs) or heart failure (HF). Regardless of medical progress, complex cardiac diseases continue to have a prolonged clinical course with high morbidity and mortality. Interventional coronary techniques together with drug therapy improve quality and future prospects of life, but do not reverse the course of the atherosclerotic process that remains relentlessly progressive. The probability of CVDs and HF phenotypes to reverse can be supported by the advances made on the medical holistic principle of systems biology (SB) and on artificial intelligence (AI). Studies on clinical phenotypes reversal should be based on the research performed in large populations of patients following gathering and analyzing large amounts of relative data that embrace the concept of complexity. To decipher the complexity conundrum, a multiomics approach is needed with network analysis of the biological data. Only by understanding the complexity of chronic heart diseases and explaining the interrelationship between different interconnected biological networks can the probability for clinical phenotypes reversal be increased.

Clinicopathological correlates of out‐of‐hospital cardiac arrests

Background

Methods

Results

Conclusion

Sudden cardiac deaths have higher proportion of left stellate ganglionitis

One of the hypothesized mechanisms of sudden cardiac death in humans is an arrhythmia precipitated by increased sympathetic outflow to a compromised heart. The stellate ganglia provide the main sympathetic innervation to the heart, where the left stellate ganglion appears to play a role in arrhythmogenesis. Case reports of sudden cardiac death have described left stellate ganglion inflammation but no larger studies have been performed. Thus, we have specifically assessed whether the left stellate ganglion was inflamed in those dying from sudden cardiac death versus other causes of death. Thirty-one left stellate ganglia were resected from cadavers diagnosed with sudden cardiac deaths and compared with 18 ganglia from cadavers diagnosed with non-sudden cardiac deaths. Ganglia were stained with hematoxylin and eosin and lymphocytic aggregates compared. The proportion of left stellate ganglion inflammation (77%) was significantly higher in deaths from sudden cardiac deaths than non-sudden cardiac deaths (33%). This study provides information on a previously recognized, but understudied, structure that may help understand sudden cardiac death. We found high prevalence of stellate ganglion inflammation and propose that this may trigger sympathetic storms.

Pattern of sudden cardiac deaths

BACKGROUND AND OBJECTIVE

Sudden cardiac death can be defined as a sudden, unexpected death caused by loss of heart function. Notwithstanding major developments in the diagnosis and treatment of heart disease, it remains the major contributing factor for deaths. This considers the pattern of sudden cardiac deaths.Methodology: This prospective study was conducted on all cases subjected to medico-legal autopsy in the forensic medicine department at a tertiary care hospital for a period of 18 months. All sudden cardiac deaths satisfying the WHO criteria were included. Unknown cases and bodies in advanced stage of decomposition were excluded.

RESULTS

Sudden cardiac deaths accounted for 55% (82 cases) of 149 cases of sudden natural deaths and 6.5% of total autopsies conducted. The age group most commonly affected by sudden cardiac death ranged from 31 to 50 years. The majority of the cadavers had 90-95% degree of stenosis of left anterior descending artery, 70-80% of right coronary artery and 60-70% left circumflex artery. Coronary insufficiency was the major cause for sudden cardiac deaths with a total of 53 (64.63%) cases.

CONCLUSION

Sudden cardiac deaths accounted for 6.5% of all the autopsies conducted and males outnumbered females with M:F ratio of 10.7:1, with mean age of 44.5 ± 12.63 years. The largest number - 60.97% - were aged between 31 and 50 years. Coronary insufficiency accounted for 64.63% of sudden cardiac deaths.

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.

The effect of age, gender, economic state, and urbanization on the temporal trend in sudden cardiac arrest: a nationwide population-based cohort study

Background

Sudden cardiac arrest (SCA) has not been well studied in Asian countries. This study investigated the temporal trends in the incidence and outcomes of SCA and the impact of age, gender, economic state, and urbanization on SCA using a nationwide population-based sample cohort of South Korea.

Methods

In the Korean National Health Insurance Service—Sample Cohort consisting of one million persons from 2003 through 2013, we identified 5,675 (0.56%) patients with SCA using ICD-10 code I46 and I49.0. We evaluated the impact of the age, gender, household income, and urbanization level on the incidence and outcome of SCA.

Results

During the study period, the overall age- and gender-adjusted annual incidence of SCA increased by 46.9% from 30.9 in 2003 to 45.4 in 2013 (per 100,000 person-years, p < 0.001 for trend). The medical cost per 100,000 person-years also greatly increased about four times (p < 0.001 for trend). The overall adjusted survival to hospital discharge rate increased from 8.9% in 2003 to 13.2% in 2013 (adjusted rate ratio per year 1.05; p < 0.001 for trend). Old age and low household incomes of the population was related to increased SCA and poor survival to hospital discharge rate. The proportion of patients with intensive or advanced therapeutic modalities after SCA greatly increased from 1.6% in 2003 to 10.0% in 2013 (p < 0.001 for trend). This increase was consistent regardless of age, gender, economic state, and urbanization level.

Conclusions

Although the incidence of SCA was increased, the outcome was improved for the decade. However, in the elderly and low-income population, the incidence of SCA continued to rise and survival outcome was not improved.

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.

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.

N-Terminal Pro-B-Type Natriuretic Peptide in Risk Stratification of Heart Failure Patients With Implantable Cardioverter-Defibrillator

Background

The prognostic value of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in heart failure (HF) is well-established. However, whether it could facilitate the risk stratification of HF patients with implantable cardioverter-defibrillator (ICD) is still unclear.

Objective

To determine the associations between baseline NT-proBNP and outcomes of all-cause mortality and first appropriate shock due to sustained ventricular tachycardia/ventricular fibrillation (VT/VF) in ICD recipients.

Methods and results

N-terminal pro-B-type natriuretic peptide was measured before ICD implant in 500 patients (mean age 60.2 ± 12.0 years; 415 (83.0%) men; 231 (46.2%) Non-ischemic dilated cardiomyopathy (DCM); 136 (27.2%) primary prevention). The median NT-proBNP was 854.3 pg/ml (interquartile range [IQR]: 402.0 to 1,817.8 pg/ml). We categorized NT-proBNP levels into quartiles and used a restricted cubic spline to evaluate its nonlinear association with outcomes. The incidence rates of mortality and first appropriate shock were 5.6 and 9.1%, respectively. After adjusting for confounding factors, multivariable Cox regression showed a rise in NT-proBNP was associated with an increased risk of all-cause mortality. Compared with the lowest quartile, the hazard ratios (HRs) with 95% CI across increasing quartiles were 1.77 (0.71, 4.43), 3.98 (1.71, 9.25), and 5.90 (2.43, 14.30) for NT-proBNP (p for trend &lt; 0.001). A restricted cubic spline demonstrated a similar pattern with an inflection point found at 3,231.4 pg/ml, beyond which the increase in NT-proBNP was not associated with increased mortality (p for nonlinearity &lt; 0.001). Fine-Gray regression was used to evaluate the association between NT-proBNP and first appropriate shock accounting for the competing risk of death. In the unadjusted, partial, and fully adjusted analysis, however, no significant association could be found regardless of NT-proBNP as a categorical variable or log-transformed continuous variable (all p &gt; 0.05). No nonlinearity was found, either (p = 0.666). Interactions between NT-proBNP and predefined factors were not found (all p &gt; 0.1).

Conclusion

In HF patients with ICD, the rise in NT-proBNP is independently associated with increased mortality until it reaches the inflection point. However, its association with the first appropriate shock was not found. Patients with higher NT-proBNP levels might derive less benefit from ICD implant.

Knowledge, Attitude and Decision-making of Nurses in the Resuscitation Team towards Terminating Resuscitation and Do-not-Resuscitate Order

Background

Making appropriate decisions for cardiopulmonary resuscitation (CPR) is very challenging for healthcare providers. This study aimed to evaluate knowledge, attitude, and decision making about do-not-resuscitate (DNR) and termination of resuscitation (ToR) among nurses in the resuscitation team.

Methods

This descriptive cross-sectional study was conducted in April-September 2020. Participants were 128 nurses from the CPR teams of two hospitals in Kermanshah and Hamedan, Iran. A valid and reliable researcher-made instrument was used for data collection. Data were analyzed using the Chi-square, Fisher's exact, and Mann-Whitney U tests, the Spearman's correlation analysis, and the logistic and rank regression analyses.

Results

Only 22.7% and 37.5% of participants had adequate knowledge about ToR and DNR. The significant predictor of DNR and ToR knowledge was educational level and the significant predictors of decision making for CPR were educational level, gender, and history of receiving CPR-related education (P<0.05). When facing a cardiac arrest and indication of DNR or ToR, 12.5% of participants reported that they would not start CPR, 21.5% of them reported that they would terminate CPR, and 14.8% of them reported that they would perform slow code. The DNR decision had significant relationship with educational level, DNR knowledge, and ToR knowledge (P< 0.05), while the ToR decision had significant relationship with educational level and ToR knowledge (P<0.05).

Conclusion

Nurses' limited DNR and ToR knowledge and physicians' conflicting orders and documentation can cause ethical challenges for nurses. Clear guidelines for DNR orders or TOR is necessary for nurses, in order to prevent any potential confusion, legal or psychosocial issues and concerns surrounding CPR and improve their involvement in CPR decision making process.

Kynurenine Pathway Metabolites as Potential Clinical Biomarkers in Coronary Artery Disease

Coronary artery disease (CAD) is one of the leading cause of mortality worldwide. Several risk factors including unhealthy lifestyle, genetic background, obesity, diabetes, hypercholesterolemia, hypertension, smoking, age, etc. contribute to the development of coronary atherosclerosis and subsequent coronary artery disease. Inflammation plays an important role in coronary artery disease development and progression. Pro-inflammatory signals promote the degradation of tryptophan via the kynurenine pathway resulting in the formation of several immunomodulatory metabolites. An unbalanced kynurenic pathway has been implicated in the pathomechanisms of various diseases including CAD. Significant improvements in detection methods in the last decades may allow simultaneous measurement of multiple metabolites of the kynurenine pathway and such a thorough analysis of the kynurenine pathway may be a valuable tool for risk stratification and determination of CAD prognosis. Nevertheless, imbalance in the activities of different branches of the kynurenine pathway may require careful interpretation. In this review, we aim to summarize clinical evidence supporting a possible use of kynurenine pathway metabolites as clinical biomarkers in various manifestations of CAD.

Arrhythmias in Female Patients: Incidence, Presentation and Management

There is a growing appreciation for differences in epidemiology, treatment, and outcomes of cardiovascular conditions by sex. Historically, cardiovascular clinical trials have under-represented females, but findings have nonetheless been applied to clinical care in a sex-agnostic manner. Thus, much of the collective knowledge about sex-specific cardiovascular outcomes result from post hoc and secondary analyses. In some cases, these investigations have revealed important sex-based differences with implications for optimizing care for female patients with arrhythmias. This review explores the available evidence related to cardiac arrhythmia care among females, with emphasis on areas in which important sex differences are known or suggested. Considerations related to improving female enrollment in clinical trials as a way to establish more robust clinical evidence for the treatment of females are discussed. Areas of remaining evidence gaps are provided, and recommendations for areas of future research and specific action items are suggested. The overarching goal is to improve appreciation for sex-based differences in cardiac arrhythmia care as 1 component of a comprehensive plan to optimize arrhythmia care for all patients.

Altered Expression of Zonula occludens-1 Affects Cardiac Na+ Channels and Increases Susceptibility to Ventricular Arrhythmias

Zonula occludens-1 (ZO-1) is an intracellular scaffolding protein that orchestrates the anchoring of membrane proteins to the cytoskeleton in epithelial and specialized tissue including the heart. There is clear evidence to support the central role of intracellular auxiliary proteins in arrhythmogenesis and previous studies have found altered ZO-1 expression associated with atrioventricular conduction abnormalities. Here, using human cardiac tissues, we identified all three isoforms of ZO-1, canonical (Transcript Variant 1, TV1), CRA_e (Transcript Variant 4, TV4), and an additionally expressed (Transcript Variant 3, TV3) in non-failing myocardium. To investigate the role of ZO-1 on ventricular arrhythmogenesis, we generated a haploinsufficient ZO-1 mouse model (ZO-1^+/-). ZO-1^+/- mice exhibited dysregulated connexin-43 protein expression and localization at the intercalated disc. While ZO-1^+/- mice did not display abnormal cardiac function at baseline, adrenergic challenge resulted in rhythm abnormalities, including premature ventricular contractions and bigeminy. At baseline, ventricular myocytes from the ZO-1^+/- mice displayed prolonged action potential duration and spontaneous depolarizations, with ZO-1^+/- cells displaying frequent unsolicited (non-paced) diastolic depolarizations leading to spontaneous activity with multiple early afterdepolarizations (EADs). Mechanistically, ZO-1 deficient myocytes displayed a reduction in sodium current density (I_Na) and an increased sensitivity to isoproterenol stimulation. Further, ZO-1 deficient myocytes displayed remodeling in I_Ca current, likely a compensatory change. Taken together, our data suggest that ZO-1 deficiency results in myocardial substrate susceptible to triggered arrhythmias.

Proteomics-Based Serum Alterations of the Human Protein Expression after Out-of-Hospital Cardiac Arrest: Pilot Study for Prognostication of Survivors vs. Non-Survivors at Day 1 after Return of Spontaneous Circulation (ROSC)

Background: Targeted temperature management (TTM) is considered standard therapy for patients after out-of-hospital cardiac arrest (OHCA), cardiopulmonary resuscitation (CPR), and return of spontaneous circulation (ROSC). To date, valid protein markers do not exist to prognosticate survivors and non-survivors before the end of TTM. The aim of this study is to identify specific protein patterns/arrays, which are useful for prediction in the very early phase after ROSC. Material and Methods: A total of 20 adult patients with ROSC (19 male, 1 female; 69.9 ± 9.5 years) were included and dichotomized in two groups (survivors and non-survivors at day 30). Serum samples were drawn at day 1 after ROSC (during TTM). Three panels (organ failure, metabolic, neurology, inflammation; OLINK, Uppsala, Sweden) were utilised. A total of four proteins were found to be differentially regulated (>2- or <−0.5-fold decrease; t-test). Bioinformatic platforms were utilised to analyse pathways and identify signalling cascades and to screen for potential biomarkers. Results: A total of 276 proteins were analysed and revealed only 11 statistically significant protein alterations (Siglec-9, LAYN, SKR3, JAM-B, N2DL-2, TNF-B, BAMBI, NUCB2, STX8, PTK7, and PVLAB). Following the Bonferroni correction, no proteins were found to be regulated as statistically significant. Concerning the protein fold change for clinical significance, four proteins (IL-1 alpha, N-CDase, IL5, CRH) were found to be regulated in a clinically relevant context. Conclusions: Early analysis at 1 day after ROSC was not sufficiently possible during TTM to prognosticate survival or non-survival after OHCA. Future studies should evaluate protein expression later in the course after ROSC to identify promising protein candidates.

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.

The Differences of CPR Duration Between Shockable and Non-shockable Rhythms in Predicting The Benefit of Target Temperature Management

BACKGROUND

Among cardiac arrest (CA) survivors, whether the combination of duration of cardiopulmonary resuscitation (CPR) and shockable/nonshockable rhythms during resuscitation can help predict the benefit of targeted temperature management (TTM) remains un-investigated.

MATERIALS AND METHODS

This multicenter retrospective cohort study enrolled 479 nontraumatic adult CA survivors with TTM and CPR duration <60 min during January 2014 to June 2019 from the TaIwan network of targeted temperature ManagEment for CARDiac arrest (TIMECARD) registry. The differences of CPR duration between shockable and nonshockable rhythms in predicting outcomes in the studied population was evaluated.

RESULTS

We observed that 205 patients (42.8%) survived to hospital discharge and 100 patients (20.9%) presented favorable neurological outcomes at discharge. The enrolled patients were further re-classified into four groups according to shockable/nonshockable rhythms and CPR duration. Patients with shockable rhythms and shorter CPR duration had better survival-to-discharge (adjusted odds ratio [OR] = 2.729, 95% confidence interval [CI] = 1.384-5.383, P = 0.004) and neurological recovery (adjusted OR = 9.029, 95%CI = 3.263-24.983, P < 0.001) than did those with nonshockable rhythms and longer CPR duration.

CONCLUSION

The CPR duration for predicting outcomes differs between CA patients with shockable and nonshockable rhythms. The combination of shockable/nonshockable rhythms and CPR duration may help predict the prognosis in CA survivors undergoing TTM.

Clinical Genetics of Inherited Arrhythmogenic Disease in the Pediatric Population

Sudden death is a rare event in the pediatric population but with a social shock due to its presentation as the first symptom in previously healthy children. Comprehensive autopsy in pediatric cases identify an inconclusive cause in 40-50% of cases. In such cases, a diagnosis of sudden arrhythmic death syndrome is suggested as the main potential cause of death. Molecular autopsy identifies nearly 30% of cases under 16 years of age carrying a pathogenic/potentially pathogenic alteration in genes associated with any inherited arrhythmogenic disease. In the last few years, despite the increasing rate of post-mortem genetic diagnosis, many families still remain without a conclusive genetic cause of the unexpected death. Current challenges in genetic diagnosis are the establishment of a correct genotype-phenotype association between genes and inherited arrhythmogenic disease, as well as the classification of variants of uncertain significance. In this review, we provide an update on the state of the art in the genetic diagnosis of inherited arrhythmogenic disease in the pediatric population. We focus on emerging publications on gene curation for genotype-phenotype associations, cases of genetic overlap and advances in the classification of variants of uncertain significance. Our goal is to facilitate the translation of genetic diagnosis to the clinical area, helping risk stratification, treatment and the genetic counselling of families.

OUP accepted manuscript

Aims

Genetic testing is recommended in specific inherited heart diseases but its role remains unclear and it is not currently recommended in unexplained cardiac arrest (UCA). We sought to assess the yield and clinical utility of genetic testing in UCA using whole-exome sequencing (WES).

Methods and results

Survivors of UCA requiring external defibrillation were included from the Cardiac Arrest Survivor with Preserved Ejection fraction Registry. Whole-exome sequencing was performed, followed by assessment of rare variants in previously reported cardiovascular disease genes. A total of 228 UCA survivors (mean age at arrest 39 ± 13 years) were included. The majority were males (66%) and of European ancestry (81%). Following advanced clinical testing at baseline, the likely aetiology of cardiac arrest was determined in 21/228 (9%) cases. Whole-exome sequencing identified a pathogenic or likely pathogenic (P/LP) variant in 23/228 (10%) of UCA survivors overall, increasing the proportion of ‘explained’ cases from 9% only following phenotyping to 18% when combining phenotyping with WES. Notably, 13 (57%) of the 23 P/LP variants identified were located in genes associated with cardiomyopathy, in the absence of a diagnosis of cardiomyopathy at the time of arrest.

Conclusions

Genetic testing identifies a disease-causing variant in 10% of apparent UCA survivors. The majority of disease-causing variants was located in cardiomyopathy-associated genes, highlighting the arrhythmogenic potential of such variants in the absence of an overt cardiomyopathy diagnosis. The present study supports the use of genetic testing including assessment of arrhythmia and cardiomyopathy genes in survivors of UCA.

The Outcome of Long QT Syndrome, a Korean Single Center Study

Congenital long QT syndrome is an inherited cardiac channelopathy, causing fatal arrhythmia. In this study, we conducted a retrospective cohort study on 105 congenital LQTS patients and its outcome in a tertiary center. The 10-year event free survival rate was 73.2%, and the outcome was different according to the genotypes. With treatment, all survived except one. The genetic analysis and risk stratification may be essential for better outcome and further nationwide and large scaled studies are required.

Background and Objectives

Although long QT syndrome (LQTS) is a potentially life-threatening inherited cardiac channelopathy, studies documenting the long-term clinical data of Korean patients with LQTS are scarce.

Methods

This retrospective cohort study included 105 patients with LQTS (48 women; 45.7%) from a single tertiary center. The clinical outcomes were analyzed for the rate of freedom from breakthrough cardiac events (BCEs), additional treatment needed, and death.

Results

LQTS was diagnosed at a median age of 11 (range, 0.003–80) years. Genetic testing was performed on 90 patients (yield, 71.1%). The proportions of genetically confirmed patients with LQTS types 1, 2, 3, and others were 34.4%, 12.2%, 12.2%, and 12.2%, respectively. In the symptomatic group (n=70), aborted cardiac arrest was observed in 30% of the patients. Treatments included medications in 60 patients (85.7%), implantable cardioverter-defibrillators in 27 (38.6%; median age, 17 years; range, 2–79 years), and left cardiac sympathetic denervation surgery in 7 (10%; median age, 13 years; range, 2–34). The 10-year BCE-free survival rate was 73.2%. By genotype, significant differences were observed in BCEs despite medication (p<0.001). The 10-year BCE-free survival rate was the highest in patients with LQTS type 1 (81.8%) and the lowest in those with multiple LQTS-associated mutations (LQTM). All patients with LQTS survived, except for one patient who had LQTM.

Conclusions

Good long-term outcomes can be achieved by using recently developed genetically tailored management strategies for patients with LQTS.