Sudden cardiac death with apparently normal heart

Sudden Cardiac Death in Patients Under 49 Years Including Adolescents: A single-centre study from Oman

Objectives

This study aimed to identify the incidence of sudden cardiac death (SCD0 in adult patients under the age of 49 years, including adolescents with an out-of-hospital cardiac arrest that presented to the emergency department of a tertiary care hospital.

Methods

This retrospective cross-sectional study was conducted at the Royal Hospital, Muscat, Oman, between January 2015 and December 2019. All patients with out-of-hospital cardiac arrest were enrolled. The incidence of SCD was evaluated. Information about the patient's demographic data, the site of cardiac arrest, the mode of arrival, the duration of pre-arrest symptoms and if cardiopulmonary resuscitation was performed was gathered. Survival data at 3-year follow-up was obtained.

Results

A total of 117 out of 769 (15%) patients met the criteria for SCD. Male gender was predominant, with a median age of 33 years. In about 79.5% of the patients, cardiac arrest was witnessed. Only 43 patients (36.8%) received cardiopulmonary resuscitation at the arrest site; 21 patients (17.9%) had a shockable rhythm and 96 patients (82.1%) had a non-shockable rhythm. Spontaneous circulation was returned in 15 patients (12.8%). Nine patients (7.7%) were discharged from the hospital and 8 (6.8%) survived at least 36 months.

Conclusion

The study findings indicate the prevalence of SCD among patients who experienced a cardiac arrest outside the hospital. Unfortunately, only a small number of patients were able to survive in the long term. By implementing preemptive screening for individuals and their families, it may be possible to prevent SCD and improve outcomes for those affected.

Primary myocardial fibrosis - a distinct entity characterized by heterogeneous histology

Primary myocardial fibrosis (PMF), defined as myocardial fibrosis in the absence of identifiable causes, may represent a common alternative phenotype in various cardiomyopathies and contribute to sudden cardiac death (SCD). No previous definitions of histopathological characteristics exist for PMF. We aimed to evaluate whether common features of fibrosis could be identified. PMF cases (n = 28) were selected from the FinGesture cohort consisting of 5,869 SCD victims that underwent a medicolegal autopsy. Twelve trauma controls and 10 ischemic heart disease cases were selected as reference groups. Further 3 PMF cases and 5 ischemic heart disease cases from autopsies performed in the University of Copenhagen, Denmark, were selected for a validation substudy. Relative area of fibrosis, amount of diffuse and perivascular fibrosis, and location of fibrosis were assessed from left ventricle myocardial samples stained with Masson trichrome. Further evaluations were performed with alpha-smooth muscle actin (α-SMA), vimentin, and CD68 stainings. Mean relative area of fibrosis was 5.8 ± 10.7%, 1.0 ± 0.7%, and 7.0 ± 7.4% in PMF, trauma controls, and ischemic cases, respectively. Fibrosis in the PMF group was mostly located in other sites than the endocardium. Most cases with fibrosis had vimentin-positive but α-SMA-negative stromal cells within fibrotic areas. Histopathologically, PMF represents a heterogeneous entity with variable fibrotic lesions affecting the whole myocardium and a suggested significant role of fibroblasts. These findings may bring validation to PMF being a common manifestation of cardiomyopathies. Evidently, PMF stands out as a particular entity demanding special attention as a cause of SCD.

Trigger and Substrate Mapping and Ablation for Ventricular Fibrillation in the Structurally Normal Heart

Sudden cardiac death (SCD) represents approximately 50% of all cardiovascular mortality in the United States. The majority of SCD occurs in individuals with structural heart disease; however, around 5% of individuals have no identifiable cause on autopsy. This proportion is even higher in those <40 years old, where SCD is particularly devastating. Ventricular fibrillation (VF) is often the terminal rhythm leading to SCD. Catheter ablation for VF has emerged as an effective tool to alter the natural history of this disease among high-risk individuals. Important advances have been made in the identification of several mechanisms involved in the initiation and maintenance of VF. Targeting the triggers of VF as well as the underlying substrate that perpetuates these lethal arrhythmias has the potential to eliminate further episodes. Although important gaps remain in our understanding of VF, catheter ablation has become an important option for individuals with refractory arrhythmias. This review outlines a contemporary approach to the mapping and ablation of VF in the structurally normal heart, specifically focusing on the following major conditions: idiopathic ventricular fibrillation, short-coupled ventricular fibrillation, and the J-wave syndromes-Brugada syndrome and early-repolarization syndrome.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Electrocardiographic markers of ventricular repolarization in the obese population: A descriptive review

Obesity is a global epidemiological problem that significantly contributes to the development of cardiovascular diseases. It is a proven factor for an increased risk of overall mortality and the occurrence of sudden cardiac death (SCD). The disease is accompanied by a structural and functional myocardium remodeling, which often results in ventricular repolarization abnormalities and contributes to the triggering of life-threatening arrhythmias. This heightened state of readiness for proarrhythmia is the cause of the sudden cardiac deaths which are recorded in this group of patients and which often constitute the first manifestation of ongoing cardiac pathology. One of the reasons for these arrhythmias may be abnormalities of ventricular muscle repolarization. In this descriptive review, we demonstrate electrocardiographic markers of ventricular repolarization (J point, QT/QTc/QTc-d, JT/JTc/JTc-d, ST segment, T wave and Tp-e/Tp-ed/Tp-e/QT), analyze their abnormalities in the obese population, and discuss their changes after weight loss.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Diagnostic and therapeutic characteristics of diabetes mellitus and risk of out-of-hospital cardiac arrest

This study aimed to evaluate the risks of diabetes mellitus (DM) on out-of-hospital cardiac arrest (OHCA) and to investigate whether the risks of DM on OHCA varied according to the diagnostic and therapeutic characteristics of diabetes. We conducted a multicenter prospective case–control study in 17 University hospitals in Korea from September 2017 to December 2020. Cases were EMS-treated OHCA patients aged 20 to 79 with a presumed cardiac etiology. Community-based controls were recruited at a 1:2 ratio after matching for age, sex, and urbanization level of residence. A structured questionnaire and laboratory findings were collected from cases and controls. Multivariable conditional logistic regression analyses were conducted to estimate the risk of DM on OHCA by characteristics. A total of 772 OHCA cases and 1544 community-based controls were analyzed. A total of 242 (31.3%) OHCAs and 292 (18.9%) controls were previously diagnosed with DM. The proportions of type I DM (10.7% vs. 2.1%) and insulin therapy (15.3% vs. 6.5%) were higher in OHCAs with DM than in controls with DM. The duration of DM was longer in OHCAs than in controls (median 12 vs. 7 years). DM was associated with an increased risk of OHCA (aOR (95% CI), 2.13 (1.64–2.75)). Compared to the no diabetes group, the risks of OHCA increased in the diabetes patients with type I DM (5.26 (1.72–16.08)) and type II DM group (1.63 (1.18–2.27)), a long duration of DM prevalence (1.04 (1.02–1.06) per 1-year prevalence duration), and a high HbA1c level (1.38 (1.19–1.60) per 1% increase). By treatment modality, the aOR (95% CI) was lowest in the oral hypoglycemic agent (1.47 (1.08–2.01)) and highest in the insulin (6.63 (3.04–14.44)) groups. DM was associated with an increased risk of OHCA, and the risk magnitudes varied according to the diagnostic and therapeutic characteristics.

The Postmortem Interpretation of Cardiac Genetic Variants of Unknown Significance in Sudden Death in the Young: A Case Report and Review of the Literature

Sudden cardiac death (SCD) in adolescents and young adults is a major traumatic event for families and communities. In these cases, it is not uncommon to have a negative autopsy with structurally and histologically normal heart. Such SCD cases are generally attributed to channelopathies, which include long QT syndrome, short QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia. Our understanding of the causes for SCDs has changed significantly with the advancements in molecular and genetic studies, where many mutations are now known to be associated with certain channelopathies. Postmortem analysis provides great value in informing decision-making with regard to screening tests and prophylactic measures that should be taken to prevent sudden death in first degree relatives of the decedent. As this is a rapidly advancing field, our ability to identify genetic mutations has surpassed our ability to interpret them. This led to a unique challenge in genetic testing called variants of unknown significance (VUS). VUSs present a diagnostic dilemma and uncertainty for clinicians and patients with regard to next steps. Caution should be exercised when interpreting VUSs since misinterpretation can result in mismanagement of patients and their families. A case of a young adult man with drowning as his proximate cause of death is presented in circumstances where cardiac genetic testing was indicated and undertaken. Eight VUSs in genes implicated in inheritable cardiac dysfunction were identified and the interpretation of VUSs in this scenario is discussed.

Cardiac Magnetic Resonance Imaging for Nonischemic Cardiac Disease in Out-of-Hospital Cardiac Arrest Survivors Treated with Targeted Temperature Management: A Multicenter Retrospective Analysis

(1) Background: Cardiac magnetic resonance (CMR) imaging is an emerging tool for investigating nonischemic cardiomyopathies and cardiac systemic disease. However, data on the cardiac arrest population are limited. This study aimed to evaluate the usefulness of CMR imaging in out-of-hospital cardiac arrest (OHCA) survivors treated with targeted temperature management (TTM). (2) Methods: We conducted the retrospective observational study using a multicenter registry of adult non-traumatic comatose OHCA survivors who underwent TTM between January 2010 and December 2019. Of the 949 patients, 389 with OHCA of non-cardiac cause, 145 with significant lesions in the coronary artery, 151 who died during TTM, 81 without further evaluation due to anticipated poor neurological outcome, and 51 whose etiology is underlying disease were excluded. In 36 of the 132 remaining patients, the etiologies included variant angina, long QT syndrome, and complete atrioventricular block in ancillary studies. Fifty-six patients were diagnosed idiopathic ventricular fibrillation without CMR. (3) Results: CMR imaging was performed in the remaining 40 patients with cardiac arrest of unknown cause. The median time from cardiac arrest to CMR imaging was 10.1 days. The CMR finding was normal in 23 patients, non-diagnostic in 12, and abnormal in 5, which suggested non-ischemic cardiomyopathy but did not support the final diagnosis. (4) Conclusions: CMR imaging may not be useful for identifying unknown causes of cardiac arrest in OHCA survivors treated with targeted temperature management without definitive diagnosis even after coronary angiography, echocardiography, and electrophysiology studies. However, further large-scale studies will be needed to confirm these findings.

Incidence and etiology of sudden cardiac arrest in Koreans: A cohort from the national health insurance service database

The incidence of sudden cardiac arrest (SCA) in Asians is lower than that seen in Western populations, but there are few available data on the incidence and associated cardiac etiology of SCA in Asians. From 2002 to 2013, patients with SCA were analyzed using a cohort from the South Korean National Health Insurance Service (NHIS) coded database. Sudden unexplained death syndrome (SUDS) was defined as cryptogenic arrest, excluding that of non-cardiac origin, coronary artery disease (CAD), cardiomyopathy (CM), and valvular heart disease. During the 12-year study period, 5,973 patients (0.53%) from the total cohort of 1,125,691 had a cardiac arrest code. The overall incidence of arrest was 48.7 per 100,000 person-years (95% CI 16.6-18.0). The incidence of primary SCA excluding those of non-cardiac origin was 16.1 per 100,000 person-years (95% CI 15.4-16.8). It was higher in males than in females (18.1 vs. 14.1 per 100,000 person-years). CAD was the most common cause of SCA (59.4%), and followed by CM (13.9%). SUDS accounted for 14.7% of SCA events. The risk of SCA had increased gradually from over 25 years old. Heart failure, atrial fibrillation and hypertension are major factors associated with SCA incidence. Our findings outline epidemiologic data for SCA and the proportion of associated cardiac etiology leads SCA in a large population.

Non-diagnostic autopsy findings in sudden unexplained death victims

BACKGROUND

Several inherited cardiac diseases may lead to sudden cardiac death (SCD) a devastating event in the families. It is crucial to establish a post mortem diagnosis to facilitate relevant work-up and treatment of family members. Sudden unexplained death (SUD) victims constitute roughly one third of all SCD cases in Denmark.

METHODS

This was a single center, retrospective study investigating SUD cases. Victims who died unexplained due to suspected or confirmed cardiac disease were consecutively referred to a third line referral center established in 2005. All autopsy reports were investigated. Victims were divided into two groups: non-diagnostic cardiac findings and normal cardiac findings. None of the included victims had findings consistent with a diagnosis based on existing criteria.

RESULTS

In total, 99 SUD cases were referred. The mean age of the victims was 37 years (range 0-62 years, 75% males). A total of 14 (14%) victims had a cardiovascular diagnosis pre-mortem. Thirty-seven cases had normal cardiac findings and non-diagnostic cardiac findings were found in 62 cases (63%). The five most common findings included ventricular hypertrophy and/or enlarged heart (n = 35, 35%), coronary atheromatosis (n = 31, 31%), myocardial fibrosis (n = 19, 19%), dilated chambers (n = 7, 7%) and myocardial inflammation (n = 5, 5%).

CONCLUSION

One third of SUD victims had normal cardiac findings and non-diagnostic cardiac findings were seen in almost two thirds of the SUD victims. These non-diagnostic findings may be precursors or early markers for underlying structural cardiac disorders or may be innocent bystanders in some cases. Further studies and improved post-mortem examination methods are needed for optimization of diagnostics in SUD.

Mitral Valve Prolapse and Sudden Cardiac Death: A Systematic Review

Background

The relationship between mitral valve prolapse (MVP) and sudden cardiac death (SCD) remains controversial. In this systematic review, we evaluate the relationship between isolated MVP and SCD to better define a potential high‐risk subtype. In addition, we determine whether premortem parameters could predict SCD in patients with MVP and the incidence of SCD in MVP.

Methods and Results

Electronic searches were conducted in PubMed and Embase for all English literature articles published between 1960 and 2018 regarding MVP and SCD or cardiac arrest. We also identified articles investigating predictors of ventricular arrhythmias or SCD and cohort studies reporting SCD outcomes in MVP. From 2180 citations, there were 79 articles describing 161 cases of MVP with SCD or cardiac arrest. The median age was 30 years and 69% of cases were female. Cardiac arrest occurred during situations of stress in 47% and was caused by ventricular fibrillation in 81%. Premature ventricular complexes on Holter monitoring (92%) were common. Most cases had bileaflet involvement (70%) with redundancy (99%) and nonsevere mitral regurgitation (83%). From 22 articles describing predictors for ventricular arrhythmias or SCD in MVP, leaflet redundancy was the only independent predictor of SCD. The incidence of SCD with MVP was estimated at 217 events per 100 000 person‐years.

Conclusions

Isolated MVP and SCD predominantly affects young females with redundant bileaflet prolapse, with cardiac arrest usually occurring as a result of ventricular arrhythmias. To better understand the complex relationship between MVP and SCD, standardized reporting of clinical, electrophysiological, and cardiac imaging parameters with longitudinal follow‐up is required.

Duration of in-hospital cardiopulmonary resuscitation and its effect on survival

OBJECTIVE

This study aims to determine the correlation between the duration of cardiopulmonary resuscitation (CPR) and the return of spontaneous circulation (ROSC) in an in-hospital cardiac arrest cohort.

METHODS

All patients (age ≥ 17 years) who underwent CPR at our institution from 2015 to 2017 were included. The primary endpoint was ROSC or death. A total of 88 patients were included in the study. The Pearson correlation of CPR duration with the establishment of ROSC was calculated using the IBM SPSS, version 25.

RESULTS

In all, 88 patients who received CPR, 55% (n = 48) experienced ROSC and survived. The remaining 45% (n = 40) of the total and 56% (n = 27) of those with ROSC died during the same hospitalization (Fig. 1). Among the 48 patients with ROSC, the documented duration of their CPR was about 10 min on average in comparison with 27.5 min CPR for patients who did not achieve ROSC (Fig. 2). Among all the patients, there was a negative correlation between the duration of the CPR and the establishment of ROSC. This is shown in Fig. 3.

CONCLUSION

Our study shows that CPR duration is inversely associated with the establishment rates of ROSC. Most of the benefits of CPR can be achieved in the first 15 min, and a further increase in the duration of CPR provides a minimal gain. Still, survival was achievable till 38 min in some cases, and the ideal duration of resuscitation should remain a bedside decision taking into consideration the whole clinical picture.

Early Repolarization Syndrome: Diagnostic and Therapeutic Approach

An early repolarization pattern can be observed in 1% up to 13% of the overall population. Whereas, this pattern was associated with a benign outcome for many years, several more recent studies demonstrated an association between early repolarization and sudden cardiac death, so-called early repolarization syndrome. In early repolarization syndrome patients, current imbalances between epi- and endo-cardial layers result in dispersion of de- and repolarization. As a consequence, J waves or ST segment elevations can be observed on these patients' surface ECGs as manifestations of those current imbalances. Whereas, an early repolarization pattern is relatively frequently found on surface ECGs in the overall population, the majority of individuals presenting with an early repolarization pattern will remain asymptomatic and the isolated presence of an early repolarization pattern does not require further intervention. The mismatch between frequently found early repolarization patterns in the overall population, low incidences of sudden cardiac deaths related to early repolarization syndrome, but fatal, grave consequences in affected patients remains a clinical challenge. More precise tools for risk stratification and identification of this minority of patients, who will experience events, remain a clinical need. This review summarizes the epidemiologic, pathophysiologic and diagnostic background and presents therapeutic options of early repolarization syndrome.

Type 2 diabetes is independently associated with all-cause mortality secondary to ventricular tachyarrhythmias

OBJECTIVES

The study sought to assess the prognostic impact of type 2 diabetes in patients presenting with ventricular tachyarrhythmias on admission.

BACKGROUND

Data regarding the prognostic outcome of diabetics presenting with ventricular tachyarrhythmias is limited.

METHODS

A large retrospective registry was used including all consecutive patients presenting with ventricular tachycardia (VT) and fibrillation (VF) on admission from 2002 to 2016. Patients with type 2 diabetes (diabetics) were compared to non-diabetics applying multivariable Cox regression models and propensity-score matching for evaluation of the primary prognostic endpoint of long-term all-cause mortality at 2 years. Secondary prognostic endpoints were cardiac death at 24 h, in-hospital death at index, all-cause mortality at 30 days, all-cause mortality in patients surviving index hospitalization at 2 years (i.e. "after discharge") and rehospitalization due to recurrent ventricular tachyarrhythmias at 2 years.

RESULTS

In 2411 unmatched high-risk patients with ventricular tachyarrhythmias, diabetes was present in 25% compared to non-diabetics (75%). Rates of VT (57% vs. 56%) and VF (43% vs. 44%) were comparable in both groups. Multivariable Cox regression models revealed diabetics associated with the primary endpoint of long-term all-cause mortality at 2 years (HR = 1.513; p = 0.001), which was still proven after propensity score matching (46% vs. 33%, log rank p = 0.001; HR = 1.525; p = 0.001). The rates of secondary endpoints were higher for in-hospital death at index, all-cause mortality at 30 days, as well as after discharge, but not for cardiac death at 24 h or rehospitalization due to recurrent ventricular tachyarrhythmias.

CONCLUSION

Presence of type 2 diabetes is independently associated with an increase of all-cause mortality in patients presenting with ventricular tachyarrhythmias on admission.

Electrocardiogram as a predictor of sudden cardiac death in middle-aged subjects without a known cardiac disease

Background

Abnormal 12‑lead electrocardiogram (ECG) findings and proposing its ability for enhanced risk prediction, majority of the studies have been carried out with elderly populations with prior cardiovascular diseases. This study aims to denote the association of sudden cardiac death (SCD) and various abnormal ECG morphologies using middle-aged population without a known cardiac disease.

Methods

In total, 9511 middle-aged subjects (mean age 42 ± 8.2 years, 52% males) without a known cardiac disease were included in this study. Risk for SCD was assessed after 10 and 30-years of follow-up.

Results

Abnormal ECG was present in 16.3% (N = 1548) of subjects. The incidence of SCD was distinctly higher among those with any ECG abnormality in 10 and 30-year follow-ups (1.7/1000 years vs. 0.6/1000 years, P < 0.001; 3.4/1000 years vs. 1.9/1000 years, P < 0.001). At 10-year point, competing risk multivariate regression model showed HR of 1.62 (95% CI 1.0–2.6, P = 0.05) for SCD in subjects with abnormal ECG. QRS duration ≥ 110 ms, QRST-angle > 100°, left ventricular hypertrophy, and T-wave inversions were the most significant independent ECG risk markers for 10-year SCD prediction with up to 3-fold risk for SCD. Those with ECG abnormalities had a 1.3-fold risk (95% CI 1.07–1.57, P = 0.007) for SCD in 30-year follow-up, whereas QRST-angle > 100°, LVH, ER ≥ 0.1 mV and ≥0.2 mV were the strongest individual predictors. Subjects with multiple ECG abnormalities had up to 6.6-fold risk for SCD (P < 0.001).

Conclusion

Several ECG abnormalities are associated with the occurrence of early and late SCD events in the middle-age subjects without known history of cardiac disease.

Diabetes mellitus and the risk of sudden cardiac death: A systematic review and meta-analysis of prospective studies

BACKGROUND

Although diabetes mellitus is an established risk factor for myocardial infarction and stroke, data on the association with sudden cardiac death are less extensive and the findings have not been entirely consistent. We therefore conducted a systematic review and meta-analysis of prospective studies on diabetes mellitus and risk of sudden cardiac death.

METHODS AND RESULTS

PubMed and Embase databases were searched up to July 18th 2017. Prospective studies that reported adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) for the association between a diabetes diagnosis or pre-diabetes and risk of sudden cardiac death were included. Summary RRs were estimated by use of a random effects model. Nineteen population-based prospective studies (11 publications) (3610 cases, 249,225 participants) and 10 patient-based prospective studies (2713 cases, 55,098 participants) were included. The summary RR for diabetes patients vs. persons without diabetes was 2.02 (95% CI: 1.81-2.25, I² = 0%, p_{heterogeneity} = 0.91) in the population-based studies. The summary RR was 1.23 (95% CI: 1.05-1.44, I² = 6%, p_{heterogeneity} = 0.34) for the association between pre-diabetes and sudden cardiac death (n = 3 studies, 1000 sudden cardiac deaths, 18,360 participants). In the patient-based studies, the summary RR of sudden cardiac death for diabetes patients vs. patients without diabetes was 1.75 (95% CI: 1.51-2.03, I² = 39%, p_{heterogeneity} = 0.10) for all patients combined, 1.63 (95% CI: 1.36-1.97, I² = 39%, n = 5) for coronary heart disease patients, and 1.85 (95% CI: 1.48-2.33, I² = 0%, n = 3) for heart failure patients.

CONCLUSIONS

These results suggest that diabetes patients are at an increased risk of sudden cardiac death both in the general population and among different patient groups.

Susceptibility to short-term ozone exposure and cardiovascular and respiratory mortality by previous hospitalizations

BACKGROUND

Ozone (O₃) has been associated with cardiorespiratory mortality although few studies have explored susceptible populations based on prior disease. We aimed to investigate the role of previous hospitalization on the association between short-term exposure to O₃ and cardiovascular (CV) and respiratory mortality.

METHODS

We performed time series analyses using generalized additive models and case-crossover on 136,624 CV and 23,281 respiratory deaths in Stockholm County (1990-2010). Deaths were linked to hospital admissions data. We constructed 2-day and 7-day averages using daily 8-h maximum for O₃ and hourly values for PM_2.5, PM₁₀, NO₂, and NO_x from a fixed monitor.

RESULTS

We observed a 0.7% (95% CI: 0.1%, 1.3%) and 2.7% (95% CI: 0.8%, 4.6%) higher risk of CV and respiratory death per 10 μg/m³ higher 2-day and 7-day average O₃ respectively. Individuals previously hospitalized for myocardial infarction demonstrated 1.8% (95% CI: 0.4%, 3.4%) higher risk of CV death per 10 μg/m³ higher 2-day average O₃ and similar associations were observed in individuals with no previous hospitalization for any cause. Individuals with previous hospitalizations did not show susceptibility towards O₃-related risk of respiratory mortality. We observed no associations for other pollutants.

CONCLUSION

Short-term ozone exposure is associated with CV and respiratory mortality and our results may suggest higher susceptibility to CV mortality following O₃ exposure in individuals previously hospitalized for myocardial infarction. Higher risks were also observed in individuals with cardiovascular death as their first presentation of disease.

Serum lipid feature and potential biomarkers of lethal ventricular tachyarrhythmia (LVTA) induced by myocardial ion channel diseases: a rat model study

To determine the cause of death in myocardial ion channel diseases (MICD)-induced sudden cardiac death (SCD) cases is a difficulty in forensic identification practices. The majority of MICD-induced SCD cases would experience lethal ventricular tachyarrhythmia (LVTA) before deaths; thus, confirming the occurrence of LVTA in bodies can offer a key evidence to identify these cases. Several lipids in the myocardia were found disturbed after LVTA; yet, whether serum lipidome would be disrupted by LVTA is not clear. Therefore, we aimed to screen lipid feature and related diagnostic markers of LVTA in serum here. An aconitine-induced LVTA-SCD rat model was produced. Blood samples before LVTA and immediately after LVTA were retrieved and related serum specimens were used for ultra-performance liquid chromatography-mass spectrometry (UPLC-MS)-based lipidomics analyses. On the basis of the defined differential lipids, a lipid-related metabolic pathway network was constructed and potential biomarkers were screened. Twelve aconitine-induced LVTA rats were produced. Totally, 188 lipids in serum were disrupted during the LVTA-SCD process, which belong to 11 lipid classes. Most of the differential lipids were correlated, suggesting that they were interacted and that the changes were holistic during LVTA process. Ten lipid pathways were activated during LVTA process; the main lipid classes involved in these pathways were ceramide, sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. Phosphatidylcholine O-40:4, sphingomyelin d46:5, and phosphatidylethanolamine 40:4 were tested as potential diagnostic markers of LVTA-SCD event in serum. The current results indicate a substantial change in serum lipidome after LVTA-SCD; lipidomics holds promise to identify MICD-induced SCDs in forensic practices.

Association of Age at Menarche With Left Ventricular Diastolic Dysfunction in Middle-Aged Women

BACKGROUND

There is sparse research on whether if early menarche is related to left ventricular (LV) diastolic dysfunction. The present study examined this relationship in Korean women.Methods and Results:In a cross-sectional study we analyzed the records of 18,910 Korean women (≥30 years) who underwent echocardiography as part of a comprehensive health examination. Age at menarche was assessed using standardized, self-administered questionnaires. Presence of LV diastolic dysfunction was determined from the echocardiographic findings. Of the 18,910 women, 3,449 had LV diastolic dysfunction. Age at menarche was inversely associated with prevalence of LV diastolic dysfunction. In a multivariable-adjusted model, odds ratios (95% confidence interval) for LV diastolic dysfunction comparing menarche age to menarche at 15-18 years were 1.77 (1.38-2.27) for <12 years, 1.31 (1.11-1.54) for 12 years, 1.26 (1.11-1.43) for 13 years, and 1.03 (0.91-1.15) for 14 years (P for trend <0.001). Adjusting for body mass index or percent fat mass partially reduced these associations.

CONCLUSIONS

This large study found an inverse relationship between menarche age and LV diastolic dysfunction. Future prospective studies are needed to investigate potential causal relationships.

Exome analysis in 34 sudden unexplained death (SUD) victims mainly identified variants in channelopathy-associated genes

Sudden cardiac death (SCD) is one of the major causes of mortality worldwide, mostly involving coronary artery disease in the elderly. In contrary, sudden death events in young victims often represent the first manifestation of undetected genetic cardiac diseases, which remained without any symptoms during lifetime. Approximately 30% of these sudden death cases have no definite cardiac etiology after a comprehensive medicolegal investigation and are therefore termed as sudden unexplained death (SUD) cases. Advances in high-throughput sequencing approaches have provided an efficient diagnostic tool to identify likely pathogenic variants in cardiovascular disease-associated genes in otherwise autopsy-negative SUD cases. The aim of this study was to genetically investigate a cohort of 34 unexplained death cases by focusing on candidate genes associated with cardiomyopathies and channelopathies. Exome analysis identified potentially disease-causing sequence alterations in 29.4% of the 34 SUD cases. Six (17.6%) individuals had variants with likely functional effects in the channelopathy-associated genes AKAP9, KCNE5, RYR2, and SEMA3A. Interestingly, four of these six SUD individuals were younger than 18 years of age. Since the total SUD cohort of this study included five children and adolescents, post-mortem molecular autopsy screening indicates a high diagnostic yield within this age group. Molecular genetic testing represents a valuable approach to uncover the cause of death in some of the SUD victims; however, 70-80% of the cases still remain elusive, emphasizing the importance of additional research to better understand the pathological mechanisms leading to a sudden death event.

Obesity and sudden cardiac death in the young: Clinical and pathological insights from a large national registry

Aims Obesity is an increasing public health problem and a risk factor for cardiovascular diseases. The aim of the study was to determine the main features and aetiologies in a large cohort of sudden cardiac deaths that occurred in obese subjects. Methods Between 1994 and 2014, 3684 consecutive cases of unexpected sudden cardiac death were referred to our cardiac pathology centre. This study was confined to young individuals (age ≤ 35 years) for whom information about body mass index was available and consisted of 1033 cases. Results Two-hundred and twelve individuals (20%) were obese. In obese sudden cardiac death victims the main post-mortem findings were: normal heart (sudden arrhythmic death syndrome) ( n = 108; 50%), unexplained left ventricular hypertrophy ( n = 25; 12%) and critical coronary artery disease ( n = 25; 12%). Less common were hypertrophic cardiomyopathy ( n = 4; 2%) and arrhythmogenic right ventricular cardiomyopathy ( n = 4;2%). When compared with non-obese sudden cardiac death victims, sudden arrhythmic death syndrome was less common (50% vs. 60%, P < 0.01), whereas left ventricular hypertrophy and critical coronary artery disease were more frequent (12% vs. 2%, P < 0.001 and 12% vs. 3%, P < 0.001, respectively). The prevalence of critical and non-critical coronary artery disease was significantly higher in obese individuals (23% vs. 10% in non-obese individuals, P < 0.001). Conclusions Various conditions underlie sudden cardiac death in obesity, with a prevalence of sudden arrhythmic death syndrome, left ventricular hypertrophy and coronary artery disease. The degree of left ventricular hypertrophy measured by heart weight is excessive even after correction for body size. Almost one in four young obese sudden death patients show some degree of coronary artery disease, underscoring the need for primary prevention in this particular subgroup.

Sudden cardiac death and antipsychotics. Part 1: Risk factors and mechanisms

Mortality from causes other than suicide is higher than expected in schizophrenia. Cardiovascular causes are most common, accounting for the majority of the 5% of sudden and unexpected deaths. Most cases have no clear explanation on post-mortem examination (‘sudden unexplained deaths’) and are thought to result from fatal arrhythmias. Prospective studies show that people with prolongation of the QT interval beyond 500 ms are at increased risk of serious arrhythmias such as ventricular tachycardia and torsade de pointes. In about 1 in 10 cases, the torsade is fatal. Most antipsychotics prolong the QTc interval in overdose but some prolong it even at therapeutic doses. Droperidol, sertindole and ziprasidone extend the QT interval by an average of 15–35 ms; quetiapine, haloperidol and olanzapine by 5 ms, to 15 ms. There is only an approximate relationship between QT prolongation and risk of sudden death, and the risk related to antipsychotics is thought to increase in people with pre-existing cardiac disease, those taking multiple QT-acting drugs and those taking antipsychotics at high dose for long periods. There is little evidence of an association with route of administration. More data are required to clarify to what extent people with mental health difficulties who die suddenly have pre-existing cardiac disease.

Sudden Cardiac Death in Children and Adolescents

Sudden cardiac death (SCD) is a rare but devastating event in children and adolescents. Etiologies include congenital heart disease, cardiomyopathies, primary arrhythmia syndromes, and miscellaneous conditions. Challenges in the diagnosis and prevention of SCD in the young are reviewed.

A time local subset feature selection for prediction of sudden cardiac death from ECG signal

Prediction of sudden cardiac death continues to gain universal attention as a promising approach to saving millions of lives threatened by sudden cardiac death (SCD). This study attempts to promote the literature from mere feature extraction analysis to developing strategies for manipulating the extracted features to target improvement of classification accuracy. To this end, a novel approach to local feature subset selection is applied using meticulous methodologies developed in previous studies of this team for extracting features from non-linear, time-frequency, and classical processes. We are therefore enabled to select features that differ from one another in each 1-min interval before the incident. Using the proposed algorithm, SCD can be predicted 12 min before the onset; thus, more propitious results are achieved. Additionally, through defining a utility function and employing statistical analysis, the alarm threshold has effectively been determined as 83%. Having selected the best combination of features, the two classes are classified using the multilayer perceptron (MLP) classifier. The most effective features would subsequently be discussed considering their prevalence in the rank-based selection. The results indicate the significant capacity of the proposed method for predicting SCD as well as selecting the appropriate processing method at any time before the incident. Graphical abstract ᅟ.

Relationship Between γ-Glutamyltransferase Levels and Left Ventricular Diastolic Dysfunction

BACKGROUND

The goal of this study was to examine the association of serum γ-glutamyltransferase (GGT) levels with left ventricular (LV) diastolic dysfunction and LV hypertrophy.Methods and Results:A cross-sectional study of 79,459 Korean men and women who underwent an echocardiography as part of a comprehensive health examination between March 2011 and December 2014. The presence of LV diastolic dysfunction and LV hypertrophy was determined using echocardiography. Of the subjects, 5,447 had LV diastolic dysfunction and 2,070 had LV hypertrophy. Both LV diastolic dysfunction and LV hypertrophy were associated with higher levels of serum GGT. Multivariable-adjusted odds ratios (95% confidence interval) for LV diastolic dysfunction comparing serum GGT quartiles 2-4 with quartile 1 were 1.25 (1.08-1.44), 1.65 (1.43-1.91) and 2.23 (1.92-2.58), respectively (P for trend <0.001). Multivariable-adjusted odds ratios (95% CI) for LV hypertrophy comparing serum GGT quartiles 2-4 with quartile 1 were 1.13 (0.94-1.36), 1.14 (0.93-1.40) and 1.33 (1.07-1.65), respectively (P for trend 0.01). These associations of serum GGT levels with LV diastolic dysfunction and LV hypertrophy were modified by age (P for interaction <0.05).

CONCLUSIONS

This study demonstrated a positive association between serum GGT levels and LV diastolic dysfunction and LV hypertrophy in a large cohort of middle-aged men and women independent of potential confounders.

Relevance of molecular testing in patients with a family history of sudden death

Sudden cardiac death (SCD) is a major cause of death in industrial countries. Although SCD occurs mainly in adults, it may also affect young persons, where genetic cardiac disorders comprise at least half of these cases. This includes primary arrhythmogenic disorders such as long QT syndrome and inherited cardiomyopathies. However, in many cases, postmortem examinations provide no conclusive results explaining the cause of death. Since family members of the deceased may eventually have inherited the same disease, they are at risk of SCD. In the present study, 28 patients with a family history of sudden unexplained death (SUD), of survived cardiac arrest and with a clinical diagnosis of an inherited cardiac disease were screened using phenotype-guided molecular analysis of genes associated with arrhythmogenic cardiac diseases. In 64% of the cases, gene variants with potentially pathogenic cardiac effects were detected suggesting that an arrhythmia syndrome may have caused the death of the deceased family member. Therefore, we recommend that relatives of SUD victims should undergo extended cardiac examination and, depending on the clinical diagnosis, a targeted genetic analysis should follow, which is crucial to identify family members at risk.

Impaired Mental Health-Related Quality of Life in Patients with Idiopathic Ventricular Fibrillation

BACKGROUND

Idiopathic ventricular fibrillation (iVF) is diagnosed in cardiac arrest survivors without an identifiable cause. Data regarding the health-related quality of life (HRQoL) in iVF patients are lacking. The purpose of this study was to investigate the HRQoL of iVF patients and to compare it to patients with an implantable cardioverter defibrillator (ICD) diagnosed with an underlying disease and healthy subjects.

METHODS

In 61 iVF patients with an ICD (iVF-ICD) and 59 ICD patients with a diagnosis (diagnosis-ICD), HRQoL was assessed using the 12-item Short-Form Health Survey (SF-12), the EuroQoL-5 dimensions (EQ-5D), the 9-item Patient Health Questionnaire, and the ICD Patient Concerns (ICDC) Questionnaire. In addition, 860 healthy subjects completed the SF-12.

RESULTS

IVF-ICD showed similar SF-12 physical summary scores compared with diagnosis-ICD patients (50.8 [interquartile range (IQR) = 42.1-53.9] vs 54.1 [IQR = 46.5-58.3]; P = 0.080) and healthy subjects (51.8 [IQR = 45.9-54.1]; P = 0.691). The mental summary score was impaired in iVF-ICD patients compared with diagnosis-ICD patients (45.9 [IQR = 40.7-49.4] vs 54.6 [IQR = 46.0-57.9]; P < 0.001) and healthy subjects (47.7 [IQR = 43.0-50.4]; P = 0.027). Scores on all five EQ-5D domains were similar between iVF-ICD patients and diagnosis-ICD patients, as well as symptoms of severe depression (19% vs 12%; P = 0.101). ICD concerns were similar between iVF-ICD and diagnosis-ICD patients (ICDC-scores 2 vs 2; P = 0.494).

CONCLUSIONS

Data suggest that there is a reduced mental HRQoL in patients with iVF compared to other cardiac arrest survivors. Screening and treatment of psychological distress should therefore be considered in iVF patients.

[Sudden cardiovascular death in adults: Study of 361 autopsy cases]

AIMS OF THE STUDY

To describe epidemiological aspects of sudden cardiovascular death and to specify the etiopathogenic characteristics.

PATIENTS AND METHOD

Our study is retrospective and descriptive. It included 361 cases of sudden cardiovascular death, which underwent autopsy in forensic medicine department of Monastir during eight years, from 1st January 2004 to 31st December 2011.

RESULTS

The incidence of sudden cardiovascular death was 9 per 100,000 person. A marked male predominance was noted. The mean age was 55.75 years. In our series, myocardial infarction represents the leading cause of sudden cardiovascular death, 57.8% of cases. Other etiologies were hypertrophic cardiomyopathy (4.7%), heart failure (1.9%), arrhythmogenic right ventricular dysplasia (2.8%), valvular disease (2%), cardio-myo-pericarditis (1.9%), hydatid cyst of the heart (0.8%), ruptured aneurysm (2.5%), pulmonary embolism (1.9%) and aortic dissection (1.3%). A sudden cardiovascular death at work was found in 25 cases. These cases pose essentially a problem of imputability.

CONCLUSION

Sudden cardiac death is usually the complication of underlying heart disease, sometimes overlooked. Several risk factors are involved. Sudden cardiac death in healthy heart or death caused by arrhythmia is an important entity seeking the intervention of several actors (forensic doctor, cardiologist, geneticist, media…) for prevention.

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Zusammenfassung. Das Brugada-Syndrom ist ein seltenes, meist familiäres Arrhythmie-Syndrom mit autosomal-dominantem Vererbungsmuster und stellt eine wichtige Differenzialdiagnose von rhythmogenen Synkopen bzw. überlebtem plötzlichen Herztod bei jungen Erwachsenen ohne strukturelle Herzerkrankung dar. Die Diagnostik ist meist erschwert, da die pathognomonischen EKG-Zeichen häufig transient sind und zur definitiven Diagnose oft eine medikamentöse Demaskierung mittels Natriumblocker nötig ist. Die ICD-Implantation ist die einzige effektive Therapie zur Prävention des plötzlichen Herztodes. Für die diesbezügliche Therapieentscheidung ist vor allem bei Zufallsbefunden und asymptomatischen Patienten eine individuelle Risikostratifizierung nötig.

Effect of preceding medications on resuscitation outcome of out-of-hospital cardiac arrest

As evidence regarding the impact of preceding medications on resuscitation outcomes has been inconsistent, this study aimed to analyze the association between preceding medications and resuscitation outcomes in patients experiencing out-of-hospital cardiac arrest (OHCA). This retrospective study included patients with OHCA presenting to a tertiary care hospital by emergency medical service (EMS) between January 2006 and June 2011. Using the Utstein template, data were collected from EMS and hospital medical records for prehospital care, in-hospital care, and medications which were taken continuously for at least 2 weeks preceding OHCA. Primary outcome was the proportion of patients with a survived event. Multivariable logistic regression analyses were performed to evaluate the predictors of survived events. Among the 1381 included patients with OHCA, 552 (40.0%) patients achieved sustained return of spontaneous circulation and 463 (33.5%) patients survived after resuscitation, 96 (7.0%) patients survived until discharge, and 20 (1.4%) patients had a favorable neurological outcome at discharge. The multivariable analyses revealed that use of statins preceding OHCA was independently associated with a greater probability of a survived events (OR=2.09, 95% CI 1.08 to 4.03, p=0.028).Use of digoxin was adversely associated with survived events (OR=0.39, 95% CI 0.16 to 0.90, p=0.028) in patients with OHCA. The continuous use of statins preceding OHCA was positively associated with survived events, while use of digoxin was adversely related. It deserves more attention on medications preceding OHCA because of their potential effect on resuscitation outcomes.

Role of risk stratification and genetics in sudden cardiac death

Sudden cardiac death (SCD) is a major public health issue due to its increasing incidence in the general population and the difficulty in identifying high-risk individuals. Nearly 300 000 - 350 000 patients in the United States and 4-5 million patients in the world die annually from SCD. Coronary artery disease and advanced heart failure are the main etiology for SCD. Ischemia of any cause precipitates lethal arrhythmias, and ventricular tachycardia and ventricular fibrillation are the most common lethal arrhythmias precipitating SCD. Pulseless electrical activity, bradyarrhythmia, and electromechanical dissociation also result in SCD. Most SCDs occur outside of the hospital setting, so it is difficult to estimate the public burden, which results in overestimating the incidence of SCD. The insufficiency and limited predictive value of various indicators and criteria for SCD result in the increasing incidence. As a result, there is a need to develop better risk stratification criteria and find modifiable variables to decrease the incidence. Primary and secondary prevention and treatment of SCD need further research. This critical review is focused on the etiology, risk factors, prognostic factors, and importance of risk stratification of SCD.

Posture and Gender Differentially Affect Heart Rate Variability of Symptomatic Mitral Valve Prolapse and Normal Adults

BACKGROUND

Heart rate variability (HRV) has been shown to be a useful measure of autonomic activity in healthy and mitral valve prolapsed (MVP) subjects. However, the effects of posture and gender on HRV in symptomatic MVP and normal adults had not been elucidated in Taiwan.

METHODS

A total of 118 MVP patients (7 males, 39 ± 7 years old; and 111 females, 42 ± 13 years old) and 148 healthy control (54 males, 28 ± 4 years old; and 94 females, 26 ± 6 years old) were investigated. The diagnosis of MVP was confirmed by cross-sectional echocardiography. A locally developed Taiwanese machine was used to record the HRV parameters for MVP and control groups in three stationary positions. Thereafter, the HRV time-domain parameters, and the frequency-domain parameters derived from fast Fourier transform or autoregressive methods were analyzed.

RESULTS

The MVP group showed a decrease in time domain parameters and obtunded postural effects on frequency domain parameters moreso than the control group. Though the parasympathetic tone was dominant in female (higher RMSSD, nHF and lower nLF vs. male), the sympathetic outflow was higher in MVP female (lower SDNN, NN50 and higher nLF vs. normal female). While the parasympathetic activity was lower in male, sympathetic outflow was dominant in MVP male (lower nHF and higher nLF vs. normal male).

CONCLUSIONS

Both MVP female and male subjects had elevated levels of sympathetic outflow. The obtunded postural effects on frequency domain measures testified to the autonomic dysregulation of MVP subjects.

Myocardial Biopsy In "Idiopathic» Atrial Fibrillation And Other Arrhythmias: Nosological Diagnosis, Clinical And Morphological Parallels, And Treatment

BACKGROUND

The nosological nature of "idiopathic" arrhythmias and the effect of etiotropic and pathogenetic treatment are often unknown.

METHODS AND RESULTS

19 patients (42.6±11.3 years, 9 women) with atrial fibrillation (n = 16), supraventricular (n = 10) and ventricular (n = 4) premature beats, supraventricular (n = 2) and ventricular tachycardia (n = 1), left bundle branch block (n= 2), AV block (n = 2) without structural heart changes. Viruses were identified (polymerase chain reaction, PCR) along with measurement of anti-heart antibodies (AHA) and endomyocardial biopsy (EMB). EMB allowed to establish diagnosis in all patients: infectious-immune myocarditis (n = 11, parvovirus-positive in 1),parvovirus-positive endomyocarditis (n = 1),systemic (n = 2) and myocardial (n = 1) vasculitis,Fabry's disease (n = 1), arrhythmogenic right ventricular dysplasia (n = 1),unspecified genetic cardiomyopathy (n = 2, herpes virus 6 one positive). Level of AHA had the greatest significance for myocarditis diagnostics. All patients with myocarditis/vasculitis had background therapy: acyclovir (n = 10), IV immunoglobulin (n = 2), meloxicam (n = 12), hydroxychloroquine (n = 15), steroids (n = 14, 31.1±12.5 mg/day), azathioprine 150 mg/day (n = 2). Median follow-up was 4 years. Treatment significantly reduced the rate of arrhythmias (8 [5;8] to 3 [1.25;7.75] points); disappearance of bundle branch block was noted.

CONCLUSION

EMB allowed to diagnose immune-mediated inflammatory diseases in 78.9% patients with 'idiopathic' arrhythmias and genetic diseases in 21.1%. Background therapy of myocarditis improved the antiarrhythmic efficiency, and allowed the best premed for interventional treatment.

Finding the rhythm of sudden cardiac death: new opportunities using induced pluripotent stem cell-derived cardiomyocytes

Sudden cardiac death is a common cause of death in patients with structural heart disease, genetic mutations, or acquired disorders affecting cardiac ion channels. A wide range of platforms exist to model and study disorders associated with sudden cardiac death. Human clinical studies are cumbersome and are thwarted by the extent of investigation that can be performed on human subjects. Animal models are limited by their degree of homology to human cardiac electrophysiology, including ion channel expression. Most commonly used cellular models are cellular transfection models, which are able to mimic the expression of a single-ion channel offering incomplete insight into changes of the action potential profile. Induced pluripotent stem cell-derived cardiomyocytes resemble, but are not identical, adult human cardiomyocytes and provide a new platform for studying arrhythmic disorders leading to sudden cardiac death. A variety of platforms exist to phenotype cellular models, including conventional and automated patch clamp, multielectrode array, and computational modeling. Induced pluripotent stem cell-derived cardiomyocytes have been used to study long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, hypertrophic cardiomyopathy, and other hereditary cardiac disorders. Although induced pluripotent stem cell-derived cardiomyocytes are distinct from adult cardiomyocytes, they provide a robust platform to advance the science and clinical care of sudden cardiac death.

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

INTRODUCTION

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

METHODS AND RESULTS

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

CONCLUSION

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

Sudden cardiac death from the perspective of coronary artery disease

Sudden cardiac death accounts for approximately 50% of all deaths attributed to cardiovascular disease in the United States. It is most commonly associated with coronary artery disease and can be its initial manifestation or may occur in the period after an acute myocardial infarction. Decreasing the rate of sudden cardiac death requires the identification and treatment of at-risk patients through evidence-based pharmacotherapy and interventional strategies aimed at primary and secondary prevention. For this review, we searched PubMed for potentially relevant articles published from January 1, 1970, through March 1, 2014, using the following key search terms: sudden cardiac death, ischemic heart disease, coronary artery disease, myocardial infarction, and cardiac arrest. Searches were enhanced by scanning bibliographies of identified articles, and those deemed relevant were selected for full-text review. This review outlines various mechanisms for sudden cardiac death in the setting of coronary artery disease, describes risk factors for sudden cardiac death, explores the management of cardiac arrest, and outlines optimal practice for the monitoring and treatment of patients after an acute ST-segment elevation myocardial infarction to decrease the risk of sudden death.

A comparison of genetic findings in sudden cardiac death victims and cardiac patients: the importance of phenotypic classification

Sudden cardiac death (SCD) is responsible for a large proportion of non-traumatic, sudden and unexpected deaths in young individuals. Sudden cardiac death is a known manifestation of several inherited cardiac diseases. In post-mortem examinations, about two-thirds of the SCD cases show structural abnormalities at autopsy. The remaining cases stay unexplained after thorough investigations and are referred to as sudden unexplained deaths. A routine forensic investigation of the SCD victims in combination with genetic testing makes it possible to establish a likely diagnosis in some of the deaths previously characterized as unexplained. Additionally, a genetic diagnose in a SCD victim with a structural disease may not only add to the differential diagnosis, but also be of importance for pre-symptomatic family screening. In the case of SCD, the optimal establishment of the cause of death and management of the family call for standardized post-mortem procedures, genetic screening, and family screening. Studies of genetic testing in patients with primary arrhythmia disorders or cardiomyopathies and of victims of SCD presumed to be due to primary arrhythmia disorders or cardiomyopathies, were systematically identified and reviewed. The frequencies of disease-causing mutation were on average between 16 and 48% in the cardiac patient studies, compared with ∼10% in the post-mortem studies. The frequency of pathogenic mutations in heart genes in cardiac patients is up to four-fold higher than that in SCD victims in a forensic setting. Still, genetic investigation of SCD victims is important for the diagnosis and the possible investigation of relatives at risk.

Complex Brugada syndrome inheritance in a family harbouring compound SCN5A and CACNA1C mutations

Brugada syndrome (BrS) is characterized by ST-segment elevation in the right precordial leads and is associated with increased risk of sudden cardiac death. We have recently reported families with BrS and SCN5A mutations where some affected members do not carry the familial mutation. We evaluated the involvement of additional genetic determinants for BrS in an affected family. We identified three distinct gene variants within a family presenting BrS (5 individuals), cardiac conduction defects (CCD, 3 individuals) and shortened QT interval (4 individuals). The first mutation is nonsense, p.Q1695*, lying within the SCN5A gene, which encodes for NaV1.5, the α-subunit of the cardiac Na(+) channel. The second mutation is missense, p.N300D, and alters the CACNA1C gene, which encodes the α-subunit CaV1.2 of the L-type cardiac Ca(2+) channel. The SCN5A mutation strictly segregates with CCD. Four out of the 5 BrS patients carry the CACNA1C variant, and three of them present shortened QT interval. One of the BrS patients carries none of these mutations but a rare variant located in the ABCC9 gene as well as his asymptomatic mother. Patch-clamp studies identified a loss-of-function of the mutated CaV1.2 channel. Western-blot experiments showed a global expression defect while increased mobility of CaV1.2 channels on cell surface was revealed by FRAP experiments. Finally, computer simulations of the two mutations recapitulated patient phenotypes. We report a rare CACNA1C mutation as causing BrS and/or shortened QT interval in a family also carrying a SCN5A stop mutation, but which does not segregate with BrS. This study underlies the complexity of BrS inheritance and its pre-symptomatic genetic screening interpretation.

Sudden Unexpected Death in North Carolina (SUDDEN): methodology review and screening results

OBJECTIVES

This paper describes the methodology for a prospective, community-based study of sudden unexpected death in Wake County, North Carolina.

METHODS

From 1 March to 29 June 2013, data of presumed cardiac arrest cases were captured from Wake County Emergency Medical Services. Participants were screened into the presumed sudden unexpected death group based on specific and sequential screening criteria, and medical and public records were collected for each participant in this group. A committee of independent cardiologists reviewed all data to determine final inclusion/exclusion of each participant into registry.

RESULTS

We received 398 presumed cardiac arrest referrals. Of these, 105 participants, age 18-65 years old, were identified as presumed sudden unexpected deaths. The primary reason for exclusion was survival to hospital (38%). Ninety-five per cent of participants in the presumed sudden unexpected death group experienced an unwitnessed death. Hypertension was present in almost 50%, while dyslipidaemia and diabetes mellitus were present in almost 25% of the same group. In addition, the presumed sudden unexpected death group includes 67.6% males (95% CI 58 to 76) whereas the control group only included 58.9% (95% CI 46 to 55) males.

CONCLUSIONS

Participant identification and data collection processes identify presumed sudden unexpected death cases and secure medical and public data for screening and final adjudication. The study infrastructure developed in Wake County will allow its expansion to other counties in North Carolina. Preliminary data indicate the study presently focuses on a population demographically representative of North Carolina.

Mechanisms underlying the autonomic modulation of ventricular fibrillation initiation--tentative prophylactic properties of vagus nerve stimulation on malignant arrhythmias in heart failure

Classical physiology teaches that vagal post-ganglionic nerves modulate the heart via acetylcholine acting at muscarinic receptors, whilst it is accepted that vagus nerve stimulation (VNS) slows heart rate, atrioventricular conduction and decreases atrial contraction; there is continued controversy as to whether the vagus has any significant direct effect on ventricular performance. Despite this, there is a significant body of evidence from experimental and clinical studies, demonstrating that the vagus nerve has an anti-arrhythmic action, protecting against induced and spontaneously occurring ventricular arrhythmias. Over 100 years ago Einbrodt first demonstrated that direct cervical VNS significantly increased the threshold for experimentally induced ventricular fibrillation. A large body of evidence has subsequently been collected supporting the existence of an anti-arrhythmic effect of the vagus on the ventricle. The development of prognostic indicators of heart rate variability and baroreceptor reflex sensitivity—measures of parasympathetic tone and reflex activation respectively—and the more recent interest in chronic VNS therapy are a direct consequence of the earlier experimental studies. Despite this, mechanisms underlying the anti-arrhythmic actions of the vagus nerve have not been fully characterised and are not well understood. This review summarises historical and recently published data to highlight the importance of this powerful endogenous protective phenomenon.

A novel approach to predict sudden cardiac death (SCD) using nonlinear and time-frequency analyses from HRV signals

Investigations show that millions of people all around the world die as the result of sudden cardiac death (SCD). These deaths can be reduced by using medical equipment, such as defibrillators, after detection. We need to propose suitable ways to assist doctors to predict sudden cardiac death with a high level of accuracy. To do this, Linear, Time-Frequency (TF) and Nonlinear features have been extracted from HRV of ECG signal. Finally, healthy people and people at risk of SCD are classified by k-Nearest Neighbor (k-NN) and Multilayer Perceptron Neural Network (MLP). To evaluate, we have compared the classification rates for both separate and combined Nonlinear and TF features. The results show that HRV signals have special features in the vicinity of the occurrence of SCD that have the ability to distinguish between patients prone to SCD and normal people. We found that the combination of Time-Frequency and Nonlinear features have a better ability to achieve higher accuracy. The experimental results show that the combination of features can predict SCD by the accuracy of 99.73%, 96.52%, 90.37% and 83.96% for the first, second, third and forth one-minute intervals, respectively, before SCD occurrence.