A common missense variant in the neuregulin 1 gene is associated with both schizophrenia and sudden cardiac death

Sudden Cardiac Death in People With Schizophrenia: Higher Risk, Poorer Resuscitation Profiles, and Differing Pathologies

BACKGROUND

People with schizophrenia account for approximately 1.0% of the population and seem to experience increased rates of sudden cardiac death (SCD).

OBJECTIVES

This study sought to determine characteristics of increased SCD in people with schizophrenia.

METHODS

The End Unexplained Cardiac Death (EndUCD) prospective state-wide registry compared people aged 15 to 50 years with and without schizophrenia who experienced SCD within a 2-year time period and were referred for forensic evaluation.

RESULTS

We identified 579 individuals, of whom 65 (11.2%) had schizophrenia. Patients with schizophrenia were more commonly smokers (46.2% vs 23.0%; P < 0.0001), consumed excess alcohol (32.3% vs 21.4%; P = 0.05), and used QTc-prolonging medications (69.2% vs 17.9%; P < 0.0001). They were less likely to arrest while exercising (0.0% vs 6.4%; P = 0.04). Unfavorable arrest-related factors included lower rates of witnessed arrest (6.2% vs 23.5%; P < 0.0001), more likely to be found in asystole (92.3% vs 73.3%; P < 0.0001), and being more likely to be found as part of a welfare check after a prolonged period of time (median 42 hours vs 12 hours; P = 0.003). There was more frequent evidence of decomposition, and they more commonly underwent autopsy (41.2% vs 26.4%; P = 0.04 and 93.8% vs 82.5%; P = 0.05), with a diagnosis of nonischemic cardiomyopathy being more common (29.2% vs 18.1%; P = 0.04).

CONCLUSIONS

People with schizophrenia account for 11% of young SCD patients referred for forensic investigations, exceeding population rates by 11-fold. They have a higher preexisting cardiac risk factor burden, unfavorable resuscitation profiles, and higher rates of nonischemic cardiomyopathy. Strategies targeting biopsychosocial support may deliver not only psychological benefits, but also help to decrease unwitnessed cardiac arrest.

Sudden cardiac arrest in patients with schizophrenia: A population-based study of resuscitation outcomes and pre-existing cardiovascular disease

Objective

Individuals with schizophrenia carry a high burden of cardiovascular disease and elevated rates of sudden cardiac arrest (SCA), but little published data is available regarding survival from SCA in this population. The authors compared cardiovascular disease burden and resuscitation outcomes following SCA in individuals with and without schizophrenia.

Methods

Case-control analysis drawn from a prospective community-based study of SCA in a large community. The authors defined cases as having a pre-SCA history of schizophrenia, and controls as individuals with SCA without a history of schizophrenia. SCA cases with schizophrenia were compared to a 1:5 age- and sex-frequency-matched sample of SCA cases without schizophrenia.

Results

The 103 SCA schizophrenia cases were as likely as the 515 cases without schizophrenia to have resuscitation attempted (75% vs. 80%; p = 0.24) and had a shorter 911 call mean response time (5.8 min vs. 6.9 min, p < 0.001). However, they were significantly less likely to present with a shockable rhythm (ventricular fibrillation/pulseless ventricular tachycardia 16% vs. 43%, p < 0.001), and less likely to survive to hospital discharge (3% vs. 14%, p = 0.008). Pre-arrest cardiovascular disease burden was similar in patients with and without schizophrenia.

Conclusions

Despite comparable resuscitation characteristics and cardiovascular disease burden, patients with schizophrenia had significantly lower rates of SCA survival. The paucity of previous research into this phenomenon warrants further investigation to identify factors that may improve survival.

Sudden Cardiac Death in Schizophrenia During Hospitalization: An Autopsy-Based Study

Schizophrenia is a severe mental disorder that is often comorbid with heart dysfunction and even sudden cardiac death (SCD). Clinical studies of SCD in schizophrenia have been largely reported, while there are limited autopsy studies that directly showed whole-scale information of such events. In this study, we present nine autopsy-based SCD cases in schizophrenia patients who died suddenly during hospitalization. Their medical records before and during hospitalization, and postmortem autopsy findings were summarized. These decedents had an average duration of schizophrenia for 6.83 ± 3.75 years with a male/female ratio of 4:5. They were all on intermittent antipsychotics medication before hospitalization and died within 15 days after hospitalization. Seven of the nine cases (77.8%) died of organic heart diseases such as severe coronary artery atherosclerosis (n = 4), myocarditis (n = 1), cardiomyopathy (n = 1), and pulmonary thromboembolism (n = 1). Two cases remained unexplained after systemic autopsy and toxicological examinations. Postmortem autopsy identified hepatic steatosis (n = 6) and respiratory inflammation (n = 3) as the most common associate extra-cardiac lesions. Our data provided autopsy-based data of SCD cases in schizophrenia and highlighted an intensive care of such patients during hospitalization.

Witnessed and unwitnessed sudden cardiac death: a nationwide study of persons aged 1-35 years

AIMS

The aim of this study is to compare clinical characteristics and causes of death among witnessed and unwitnessed sudden cardiac death (SCD) cases aged 1-35 years.

METHODS AND RESULTS

In this retrospective nationwide study, all deaths in persons aged 1-35 years in Denmark during 2000-09 were included (23.7 million person-years). Using the in-depth descriptive Danish death certificates and Danish nationwide registries, 860 cases of sudden, unexpected death were identified. Through review of autopsy reports and register data, we identified 635 cases of SCD of which 266 (42%) were witnessed and 326 (51%) were unwitnessed. In 43 cases (7%), witnessed status was missing. Clinical characteristics were overall similar between the two groups. We found a male predominance among unwitnessed SCD compared to witnessed SCD (71% and 62%, respectively, P-value 0.012), as well as more psychiatric comorbidity (20% and 13%, respectively, P-value 0.029). Unwitnessed SCD more often occurred during sleep whereas witnessed SCD more often occurred while the individual was awake and relaxed (P-value < 0.001). The autopsy rate among all SCD cases was 70% with no significant difference in autopsy rate between the two groups. Sudden unexplained death, which was the leading autopsy conclusion in both groups, was more frequent among unwitnessed SCD (P-value 0.001).

CONCLUSION

Several clinical characteristics and autopsy findings were similar between witnessed and unwitnessed SCD cases. Our data support the inclusion of both witnessed and unwitnessed cases in epidemiological studies of SCD cases aged 1-35 years, although the risk of misclassification is higher among unwitnessed and non-autopsied cases of SCD.

Genetic investigations of 100 inherited cardiac disease-related genes in deceased individuals with schizophrenia

Cardiac diseases and sudden cardiac death (SCD) are more prevalent in individuals diagnosed with schizophrenia compared to the general population, with especially coronary artery disease (CAD) as the major cardiovascular cause of death. Antipsychotic medications, genetics, and lifestyle factors may contribute to the increased SCD in individuals with schizophrenia. The role of antipsychotic medications and lifestyle factors have been widely investigated, while the genetic predisposition to inherited cardiac diseases in schizophrenia is poorly understood. In this study, we examined 100 genes associated with inherited cardiomyopathies and cardiac channelopathies in 97 deceased individuals diagnosed with schizophrenia for the prevalence of genetic variants associated with SCD. The deceased individuals had various causes of death and were included in the SURVIVE project, a prospective, autopsy-based study of mentally ill individuals in Denmark. This is the first study of multiple inherited cardiac disease-related genes in deceased individuals with diagnosed schizophrenia to shed light on the genetic predisposition to SCD in individuals with schizophrenia. We found no evidence for an overrepresentation of rare variants with high penetrance in inherited cardiac diseases, following the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG) consensus guidelines. However, we found that the deceased individuals had a statistically significantly increased polygenic burden caused by variants in the investigated heart genes compared to the general population. This indicates that common variants with smaller effects in heart genes may play a role in schizophrenia.

Causes of Sudden Unexpected Death in Schizophrenia Patients: A Forensic Autopsy Population Study

BACKGROUND

Schizophrenia is a detrimental psychiatric disorder, with an increased mortality from natural and nonnatural causes.

METHODS

This study was a retrospective review of autopsy cases of all the individuals with history of schizophrenia investigated by the Office of the Chief Medical Examiner, State of Maryland, for a 5-year period from 2008 to 2012.

RESULT

A total of 391 schizophrenia patients were autopsied at the Office of the Chief Medical Examiner because they died suddenly and unexpectedly. Their age ranged from 15 to 100 years with the mean age of 49.5 years. Of the 391 deaths, 191 (48.8%) were white, 185 (47.3%) were African American, and 15 (3.9%) were either Hispanic or Asian. The male and female ratio was 1.5:1. The majority of deaths (64.2%) were caused by natural diseases, 12.0% deaths were accidents, 11.5% deaths were suicides, and 9.7% deaths were homicides. The manner of death remained undetermined in 38 cases (9.7%). Of the 251 natural deaths, 198 cases (78.9%) were owing to cardiovascular diseases. Cause of death was listed as cardiac arrhythmia in 11 cases. This diagnosis of cardiac arrhythmia was made by exclusion based on death scene investigation, review of medical history, complete autopsy, and toxicological tests. Drug intoxication was the second most common cause of death.

CONCLUSIONS

The study shows high fatality caused by cardiovascular diseases and drug intoxication among schizophrenia patients, which calls attention of the medical community to closely monitor the high risk factors of sudden death among schizophrenia patients.

A critical review of zebrafish schizophrenia models: Time for validation?

Schizophrenia is a mental disorder that affects 1% of the population worldwide and is manifested as a broad spectrum of symptoms, from hallucinations to memory impairment. It is believed that genetic and/or environmental factors may contribute to the occurrence of this disease. Recently, the zebrafish has emerged as a valuable and attractive model for various neurological disorders including schizophrenia. In this review, we describe current pharmacological models of schizophrenia with special emphasis on providing insights into the pros and cons of using zebrafish as a behavioural model of this disease. Moreover, we highlight the advantages and utility of using zebrafish for elucidating the genetic mechanisms underlying this psychiatric disorder. We believe that the zebrafish has high potential also in the area of precision medicine and may complement the development of therapeutics, especially for pharmacoresistant patients.

Usefulness of Single Nucleotide Polymorphisms as Predictors of Sudden Cardiac Death

The pathophysiology of sudden cardiac death (SCD) remains incompletely understood. Genetic mutations can create a favorable substrate for SCD. Our aim is to evaluate the evidence of single nucleotide polymorphisms (SNPs) as predictors of SCD. We searched the Medline database (2000 to 2017) and selected all case-control or cohort studies that reported associations between SNPs and SCD. Our search terms included "polymorphisms" and "sudden death." We collected the study design, population ethnic background, gene testing strategy, the association between the SNP and SCD, and the cardiovascular comorbidities of the population. Our search yielded 723 studies, of which we included 24 based upon our inclusion criteria. The studies had a total population of 78,165 participants, with a median age of 62.5 years (IQR 56 to 66) and 35% (IQR 13 to 32) were female. Almost all studies were conducted in white patients of European descent and the most commonly used genetic strategy was candidate gene panels. Fifteen of the studies had a case-control design that included SCD patients without known heart disease as the comparison group and the other 9 studies included patients with heart failure and coronary artery disease. The studies evaluated 53 SNPs and the most common genetic loci were SCN5A, RyR2, CASQ2, NOSA1P, and AGTR. SNPs with the 3 strongest statistically significant ORs >1 were: rs6684209 of CASQ2 (odds ratio [OR] 19), rs3814843 of CALM1 (OR 5.5), and rs35594137 of GJA5 (OR 3.6). In Conclusion, many SNPs are associated with SCD, with the strongest associations seen in SNPs of genes related to intracellular calcium handling. These findings were generated primarily using a candidate gene strategy in white patients with European descent.

Pretreatment with neuregulin-1 improves cardiac electrophysiological properties in a rat model of myocardial infarction

Neuregulin-1 (NRG-1) is considered to be a potential therapeutic agent for cardiovascular diseases due to its diverse protective effects. The aim of the present study was to investigate the effect of NRG-1 on cardiac electrophysiology in rats with myocardial infarction (MI). The rats were randomly divided into three groups: The sham operation group (SO; n=8); MI group (n=8); and the MI with recombinant human NRG (rhNRG)-1 administration group (NRG-1 group; 10 µg/kg; n=8). A rat MI model was established via ligation of the left anterior descending coronary artery. The rats in the NRG-1 group received a 10 µg/kg rhNRG-1 injection through the tail vein 30 min prior to ligation. Following 24 h of intervention, the field potential (FP) parameters, including the interspike interval (ISI), field potential duration (FPD), FPrise, FPmin, FPmax and conduction velocity (CV), were measured using microelectrode array technology. Subsequently, burst pacing was performed to assess ventricular arrhythmia (VA) susceptibility in the left ventricle. FP parameters in the MI group were significantly different when compared with those observed in the SO group. ISI, FPD, FPrise and FPmax in the infarct, peri-infarct and normal zones, as well as the CV of the infarct and peri-infarct zones, were all significantly decreased, and FPmin in the normal zone was increased (P<0.05). However, when compared with the MI group, NRG-1 prolonged the ISI and FPD in the 3 zones, and increased FPrise in the infarct zone, FPmax in the normal zone and CV in the peri-infarct zone; it also decreased FPmin in the normal zone (P<0.05). Furthermore, the incidence of VA was significantly reduced in the NRG-1 group when compared with the MI group (P<0.05). In conclusion, NRG-1 improved cardiac electrophysiological properties and reduced VA susceptibility in acute MI.

[Electrocardiographic and hemodynamic profile of patients with psychotic disorder]

INTRODUCTION

Cardiac mortality among patients diagnosed with mental disorders is higher compared to the general population. Some authors suggest that cardiovascular risk is related to intrinsic factors specific to psychiatric disease. Nevertheless, the interpretation of these results is limited by the concomitant prescription of antipsychotics which have a cardiovascular effect. Studies evaluating the hemodynamic and electrocardiographic profile of drug naïve or drug-free patients suffering from mental disorders remain few.

AIMS

The aims of this work were to study the electrocardiographic and hemodynamic profile of drug naïve or drug-free patients with mental disorders and to determine clinical and biological factors associated with any electrocardiographic abnormalities.

SUBJECTS AND METHODS

It was a descriptive and evaluative cross-sectional study. We enrolled drug naïve or drug-free patients for at least two months. All subjects were inpatients and had at admission clinical, biological and electrocardiographic evaluation.

RESULTS

Forty-four percent of the sample had asymptomatic electrocardiographic abnormalities. These subjects had lower serum thyroid hormone levels compared to healthy group (P=0.066). Hemodynamic profile showed that 12% of the population had orthostatic hypotension.

CONCLUSION

Electrocardiographic and hemodynamic abnormalities are common among drug-free or drug naïve patients diagnosed with psychotic disorders. The association of electrocardiographic abnormalities with low levels of thyroxin requires more investigation.

Sudden death in schizophrenia

PURPOSE OF REVIEW

To examine the recent literature regarding sudden death in patients with schizophrenia and synthesize salient conclusions based on this evidence.

RECENT FINDINGS

Sudden cardiac death (SCD) is the largest subset of sudden unexpected death (SUD), with up to 40% of SUD from cardiovascular causes. SCD has been associated with exposure to both first and second-generation antipsychotics. Clozapine [odds ratio (OR) 3.67, 95% confidence interval (CI) 1.94-6.94] confers the highest risk of SCD followed by risperidone (OR 3.04, 95% CI 2.39-3.86) then olanzapine (OR 2.04, 95% CI 1.52-2.74). SCD not associated with antipsychotic use has been correlated to several modifiable and nonmodifiable risk factors - obesity, smoking, dyslipidemia, diabetes, hypertension, age, sex, and history of cardiovascular disease. Other subsets of SUD include hematological and pulmonary causes, including agranulocytosis leading to sepsis, deep vein thrombosis leading to pulmonary embolisms, and aspiration pneumonia leading to sepsis.

SUMMARY

There is a huge paucity in genetic and pharmacogenetic data focused on SUD in schizophrenia. Future studies should emphasize the genetic aspects as well as clarify the underlying molecular mechanisms of these pathways. Additionally, early detection of those patients at high risk for SUD and discovery of preventive measures should also be emphasized.

Genetic variations involved in sudden cardiac death and their associations and interactions

Although the mechanism of sudden cardiac death (SCD) in heart failure is not completely known, genetic variations are known to play key roles in this process. Increasing numbers of mutations and variants are being discovered through genome-wide association studies. The genetic variations involved in the mechanisms of SCD have aroused widespread concern. Comprehensive understanding of the genetic variations involved in SCD may help prevent it. To this end, we briefly reviewed the genetic variations involved in SCD and their associations and interactions, and observed that cardiac ion channels are the core molecules involved in this process. Genetic variations involved in cardiac structure, cardiogenesis and development, cell division and differentiation, and DNA replication and transcription are all speculated to be loci involved in SCD. Additionally, the systems involved in neurohumoral regulation as well as substance and energy metabolism are also potentially responsible for susceptibility to SCD. They form an elaborate network and mutually interact with each other to govern the fate of SCD-susceptible individuals.

A Common Variant in SCN5A and the Risk of Ventricular Fibrillation Caused by First ST-Segment Elevation Myocardial Infarction

BACKGROUND

Several common genetic variants have been associated with either ventricular fibrillation (VF) or sudden cardiac death (SCD). However, replication efforts have been limited. Therefore, we aimed to analyze whether such variants may contribute to VF caused by first ST-elevation myocardial infarction (STEMI).

METHODS

We analyzed 27 single nucleotide polymorphisms (SNP) previously associated with SCD/VF in other cohorts, and examined whether these SNPs were associated with VF caused by first STEMI in the GEnetic causes of Ventricular Arrhythmias in patients with first ST-elevation Myocardial Infarction (GEVAMI) study on ethnical Danes. The GEVAMI study is a prospective case-control study involving 257 cases (STEMI with VF) and 537 controls (STEMI without VF).

RESULTS

Of the 27 candidate SNPs, one SNP (rs11720524) located in intron 1 of SCN5A which was previously associated with SCD was significantly associated with VF caused by first STEMI. The major C-allele of rs11720524 was present in 64% of the cases and the C/C genotype was significantly associated with VF with an odds ratio (OR) of 1.87 (95% CI: 1.12-3.12; P = 0.017). After controlling for clinical differences between cases and controls such as age, sex, family history of sudden death, alcohol consumption, previous atrial fibrillation, statin use, angina, culprit artery, and thrombolysis in myocardial infarction (TIMI) flow, the C/C genotype of rs11720524 was still significantly associated with VF with an OR of 1.9 (95% CI: 1.05-3.43; P = 0.032). Marginal associations with VF were also found for rs9388451 in HEY2 gene. The CC genotype showed an insignificant risk for VF with OR = 1.50 (95% CI: 0.96-2.40; P = 0.070).

CONCLUSION

One common intronic variant in SCN5A suggested an association with VF caused by first STEMI. Further studies into the functional abnormalities associated with the noncoding variant in SCN5A may lead to important insights into predisposition to VF during STEMI.

Effects of prolonged antipsychotic administration on neuregulin-1/ErbB signaling in rat prefrontal cortex and myocardium: implications for the therapeutic action and cardiac adverse effect

Patients with schizophrenia (SCZ) are at higher risk for developing cardiovascular disease (CVD) and neuregulin-1 (NRG1)/ErbB signaling has been identified as a common susceptibility pathway for the comorbidity. Antipsychotic treatment can change NRG1/ErbB signaling in the brain, which has been implicated in their therapeutic actions, whereas the drug-induced alterations of NRG1/ErbB pathway in cardiovascular system might be associated with the prominent cardiac side-effects of antipsychotic medication. To test this hypothesis, we examined NRG1/ErbB system in rat prefrontal cortex (PFC) and myocardium following 4-week intraperitoneal administration of haloperidol, risperidone or clozapine. Generally, the antipsychotics significantly enhanced NRG1/ErbB signaling with increased expression of NRG1 and phosphorylation of ErbB4 and ErbB2 in the brain and myocardium, except that clozapine partly blocked the cardiac NRG1/ErbB2 activation, which could be associated with its more severe cardiac adverse actions. Combined, our data firstly showed evidence of the effect of antipsychotic exposure on myocardial NRG1/ErbB signaling, along with the activated NRG1/ErbB system in brain, providing a potential link between the therapeutic actions and cardiotoxicity.

ErbB4 Gene Polymorphism Is Associated With the Risk and Prognosis of Congestive Heart Failure in a Northern Han Chinese Population

BACKGROUND

There has been no research evaluating the association between human Neuregulin (NRG) 1/ErbB2/ErbB4 gene polymorphisms and heart failure risk.

METHODS AND RESULTS

Genotyping of 13 single nucleotide polymorphisms (SNPs) in the NRG-1/ErbB2/ErbB4 genes was performed in 569 unrelated heart failure patients and 682 healthy controls from a Northern Han Chinese population with the use of iPlex SNP Genotyping analysis on a Sequenom Massarray System. In the ErbB4 gene, the variants rs10932374 and rs1595064 were associated with reduced risk of heart failure under allelic, recessive and additive genetic models, and the variants rs13003941 and rs1595065 were associated with increased risk of heart failure under allelic, dominant, and additive models. The G-G-C-C-T haplotype of rs10932374-rs13003941-rs1595064-rs1595065-rs3748960 in the ErbB4 gene increased the risk of heart failure (odd ratio 1.35, 95% confidence interval [CI] 1.06-1.70; P = .014). The T variant of rs13003941 was associated with larger left ventricle (dominant model, P = .014; additive model, P = .048), and increased risk of overall death (relative risk [RR] 1.48, 95% CI 1.01-2.18; P = .045) and cardiovascular death (RR 1.56, 95% CI 1.04-2.33; P = .03) after adjusting for age and sex. NRG-1/ErbB2 gene polymorphisms were not associated with heart failure risk or prognosis.

CONCLUSION

ErbB4 gene polymorphisms were associated with the risk, severity, and prognosis of heart failure in a Northern Han Chinese population.

Cumulative effects of common genetic variants on risk of sudden cardiac death

BACKGROUND

Genome-wide association studies and candidate-gene based approaches have identified multiple common variants associated with increased risk of sudden cardiac death (SCD). However, the independent contribution of these individual loci to disease risk is modest.

OBJECTIVE

To investigate the cumulative effects of genetic variants previously associated with SCD risk.

METHODS

A total of 966 SCD cases from the Oregon-Sudden Unexpected Death Study and 1,926 coronary artery disease controls from the Wellcome Trust Case-Control Consortium were investigated. We generated genetic risk scores (GRS) for each trait composed of variants previously associated with SCD or with abnormalities in specific electrocardiographic traits such as QRS duration, QTc interval and heart rate. GRSs were calculated using a weighted approach based on the number of risk alleles weighted by the beta coefficients derived from the original studies. We also compared the highest and lowest quintiles for the GRS composed of SCD SNPs.

RESULTS

Increased cumulative risk was observed for a GRS composed of 14 SCD-SNPs (OR=1.17 [1.05-1.29], P = 0.002). The risk for SCD was 1.5 fold higher in the highest quintile when compared to the lowest quintile (OR = 1.46[1.11-1.92]). We did not observe significant associations with SCD for SNPs that determine electrocardiographic traits.

CONCLUSIONS

A modest but significant effect on SCD risk was identified for a GRS composed of 14 previously associated SCD SNPs. While next generation sequencing methodology will continue to identify additional novel variants, these findings represent proof of concept for the additive effects of gene variants on SCD risk.

The roles of neuregulin-1 in cardiac development, homeostasis, and disease

Neuregulin-1 (NRG-1) and its signaling receptors, erythroblastic leukemia viral oncogene homologs (ErbB) 2, 3, and 4, have been implicated in both cardiomyocyte development and disease, as well as in homeostatic cardiac function. NRG-1/ErbB signaling is involved in a multitude of cardiac processes ranging from myocardial and cardiac conduction system development to angiogenic support of cardiomyocytes, to cardioprotective effects upon injury. Numerous studies of NRG-1 employ a variety of platforms, including in vitro assays, animal models, and human clinical trials, with equally varying and, sometimes, contradictory outcomes. NRG-1 has the potential to be used as a therapeutic tool in stem cell therapies, tissue engineering applications, and clinical diagnostics and treatment. This review presents a concise summary of the growing body of literature to highlight the temporally persistent significance of NRG-1/ErbB signaling throughout development, homeostasis, and disease in the heart, specifically in cardiomyocytes.

Genetic markers of repolarization and arrhythmic events after acute coronary syndromes

BACKGROUND

There is a genetic contribution to the risk of ventricular arrhythmias in survivors of acute coronary syndromes (ACS). We wished to explore the role of 33 candidate single nucleotide polymorphisms (SNPs) in prolonged repolarization and sudden death in patients surviving ACS.

METHODS

A total of 2,139 patients (1680 white ethnicity) surviving an admission for ACS were enrolled in the prospective Coronary Disease Cohort Study. Extensive clinical, echocardiographic, and neurohormonal data were collected for 12 months, and clinical events were recorded for a median of 5 years. Each SNP was assessed for association with sudden cardiac death (SCD)/cardiac arrest (CA) and prolonged repolarization at 3 time-points: index admission, 1 month, and 12 months postdischarge.

RESULTS

One hundred six SCD/CA events occurred during follow-up (6.3%). Three SNPs from 3 genes (rs17779747 [KCNJ2], rs876188 [C14orf64], rs3864180 [GPC5]) were significantly associated with SCD/CA in multivariable models (after correction for multiple testing); the minor allele of rs17779747 with a decreased risk (hazard ratio [HR] 0.68 per copy of the minor allele, 95% CI 0.50-0.92, P = .012), and rs876188 and rs386418 with an increased risk (HR 1.52 [95% CI 1.10-2.09, P = .011] and HR 1.34 [95% CI 1.04-1.82, P = .023], respectively). At 12 months postdischarge, rs10494366 and rs12143842 (NOS1AP) were significant predictors of prolonged repolarization (HR 1.32 [95% CI 1.04-1.67, P = .022] and HR 1.30 [95% CI 1.01-1.66, P = .038], respectively), but not at earlier time-points.

CONCLUSION

Three SNPs were associated with SCD/CA. Repolarization time was associated with variation in the NOS1AP gene. This study demonstrates a possible role for SNPs in risk stratification for arrhythmic events after ACS.

Etiology of cardiovascular disease in patients with schizophrenia: current perspectives

Cardiovascular morbidity and mortality are important problems among patients with schizophrenia. A wide spectrum of reasons, ranging from genes to the environment, are held responsible for causing the cardiovascular risk factors that may lead to shortening the life expectancy of patients with schizophrenia. Here, we have summarized the etiologic issues related with the cardiovascular risk factors in schizophrenia. First, we focused on heritable factors associated with cardiovascular disease and schizophrenia by mentioning studies about genetics-epigenetics, in the first-episode or drug-naïve patients. In this context, the association and candidate gene studies about metabolic disturbances in schizophrenia are reviewed, and the lack of the effects of epigenetic/posttranscriptional factors such as microRNAs is mentioned. Increased rates of type 2 diabetes mellitus and disrupted metabolic parameters in schizophrenia are forcing clinicians to struggle with metabolic syndrome parameters and related issues, which are also the underlying causes for the risk of having cardiometabolic and cardiovascular etiology. Second, we summarized the findings of metabolic syndrome-related entities and discussed the influence of the illness itself, antipsychotic drug treatment, and the possible disadvantageous lifestyle on the occurrence of metabolic syndrome (MetS) or diabetes mellitus. Third, we emphasized on the risk factors of sudden cardiac death in patients with schizophrenia. We reviewed the findings on the arrhythmias such as QT prolongation, which is a risk factor for Torsade de Pointes and sudden cardiac death or P-wave prolongation that is a risk factor for atrial fibrillation. For example, the use of antipsychotics is an important reason for the prolongation of QT and some other cardiac autonomic dysfunctions. Additionally, we discussed relatively rare issues such as myocarditis and cardiomyopathy, which are important for prognosis in schizophrenia that may have originated from the use of antipsychotic medication. In conclusion, we considered that the studies and awareness about physical needs of patients with schizophrenia are increasing. It seems logical to increase cooperation and shared care between the different health care professionals to screen and treat cardiovascular disease (CVD)-risk factors, MetS, and diabetes in patients with psychiatric disorders, because some risk factors of MetS or CVD are avoidable or at least modifiable to decrease high mortality in schizophrenia. We suggested that future research should focus on conducting an integrated system of studies based on a holistic biopsychosocial evaluation.

Neuregulin as a heart failure therapy and mediator of reverse remodeling

The beta isoform of Neuregulin-1 (NRG-1β), along with its receptors (ErbB2-4), is required for cardiac development. NRG-1β, as well as the ErbB2 and ErbB4 receptors, is also essential for maintenance of adult heart function. These observations have led to its evaluation as a therapeutic for heart failure. Animal studies and ongoing clinical trials have demonstrated beneficial effects of two forms of recombinant NRG-1β on cardiac function. In addition to the possible role for recombinant NRG-1βs as heart failure therapies, endogenous NRG-1β/ErbB signaling appears to play a role in restoring cardiac function after injury. The potential mechanisms by which NRG-1β may act as both a therapy and a mediator of reverse remodeling remain incompletely understood. In addition to direct effects on cardiac myocytes NRG-1β acts on the vasculature, interstitium, cardiac fibroblasts, and hematopoietic and immune cells, which, collectively, may contribute to NRG-1β's role in maintaining cardiac structure and function, as well as mediating reverse remodeling.

Neuregulin-1/erbB activities with focus on the susceptibility of the heart to anthracyclines

Neuregulin-1 (NRG1) signaling through the tyrosine kinase receptors erbB2 and erbB4 is required for cardiac morphogenesis, and it plays an essential role in maintaining the myocardial architecture during adulthood. The tyrosine kinase receptor erbB2 was first linked to the amplification and overexpression of erbb2 gene in a subtype of breast tumor cells, which is indicative of highly proliferative cells and likely a poor prognosis following conventional chemotherapy. The development of targeted therapies to block the survival of erbB2-positive cancer cells revealed that impaired NRG1 signaling through erbB2/erbB4 heterodimers combined with anthracycline chemotherapy may lead to dilated cardiomyopathy in a subpopulation of treated patients. The ventricular-specific deletion of either erbb2 or erbb4 manifested dilated cardiomyopathy, which is aggravated by the administration of doxorubicin. Based on the exacerbated toxicity displayed by the combined treatment, it is expected that the relevant pathways would be affected in a synergistic manner. This review examines the NRG1 activities that were monitored in different model systems, focusing on the emerging pathways and molecular targets, which may aid in understanding the acquired dilated cardiomyopathy that occurs under the conditions of NRG1-deficient signaling.

QT is longer in drug-free patients with schizophrenia compared with age-matched healthy subjects

The potassium voltage-gated channel KCNH2 is a well-known gene in which mutations induce familial QT interval prolongation. KCNH2 is suggested to be a risk gene for schizophrenia. Additionally, the disturbance of autonomic control, which affects the QT interval, is known in schizophrenia. Therefore, we speculate that schizophrenic patients have characteristic features in terms of the QT interval in addition to the effect of antipsychotic medication. The QT interval of patients with schizophrenia not receiving antipsychotics (n = 85) was compared with that of patients with schizophrenia receiving relatively large doses of antipsychotics (n = 85) and healthy volunteers (n = 85). The QT interval was corrected using four methods (Bazett, Fridericia, Framingham or Hodges method). In ANCOVA with age and heart rate as covariates, patients not receiving antipsychotic treatment had longer QT intervals than did the healthy volunteers, but antipsychotics prolonged the QT interval regardless of the correction method used (P<0.01). Schizophrenic patients with and without medication had a significantly higher mean heart rate than did the healthy volunteers, with no obvious sex-related differences in the QT interval. The QT interval prolongation may be manifestation of a certain biological feature of schizophrenia.

Brugada syndrome ECG is highly prevalent in schizophrenia

BACKGROUND

The causes of increased risk of sudden cardiac death in schizophrenia are not resolved. We aimed to establish (1) whether ECG markers of sudden cardiac death risk, in particular Brugada-ECG pattern, are more prevalent among patients with schizophrenia, and (2) whether increased prevalence of these ECG markers in schizophrenia is explained by confounding factors, notably sodium channel-blocking medication.

METHODS AND RESULTS

In a cross-sectional study, we analyzed ECGs of a cohort of 275 patients with schizophrenia, along with medication use. We determined whether Brugada-ECG was present and assessed standard ECG measures (heart rate, PQ-, QRS-, and QT-intervals). We compared the findings with nonschizophrenic individuals of comparable age (the Netherlands Study of Depression and Anxiety [NESDA] cohort; N=179) and, to account for assumed increased aging rate in schizophrenia, with individuals 20 years older (Hoorn cohort; n=1168), using multivariate regression models. Brugada-ECG was significantly more prevalent in the schizophrenia cohort (11.6%) compared with NESDA controls (1.1%) or Hoorn controls (2.4%). Moreover, patients with schizophrenia had longer QT-intervals (410.9 versus 393.1 and 401.9 ms; both P<0.05), increased proportion of mild or severe QTc prolongation (13.1% and 5.8% versus 3.4% and 0.0% [NESDA], versus 5.1 and 2.8% [Hoorn]), and higher heart rates (80.8 versus 61.7 and 68.0 beats per minute; both P<0.05). The prevalence of Brugada-ECG was still increased (9.6%) when patients with schizophrenia without sodium channel-blocking medication were compared with either of the control cohorts.

CONCLUSIONS

Brugada-ECG has increased prevalence among patients with schizophrenia. This association is not explained by the use of sodium channel-blocking medication.

Genetics of sudden cardiac death caused by ventricular arrhythmias

Sudden cardiac death (SCD) resulting from ventricular tachyarrhythmia is a major contributor to mortality. Clinical management of SCD, currently based on clinical markers of SCD risk, can be improved by integrating genetic information. The identification of multiple disease-causing gene variants has already improved patient management and increased our understanding of the rare Mendelian diseases associated with SCD risk in the young, but marked variability in disease severity suggests that additional genetic modifiers exist. Next-generation DNA sequencing could be crucial to the discovery of SCD-associated genes, but large data sets can be difficult to interpret. SCD usually occurs in patients with an average age of 65 years who have complex cardiac disease stemming from multiple, common, acquired disorders. Heritable factors are largely unknown, but are likely to have a role in determining the risk of SCD in these patients. Numerous genetic loci have been identified that affect electrocardiogram indices, which are regarded as intermediate phenotypes for tachyarrhythmia. These loci could help to identify new molecules and pathways affecting cardiac electrical function. These loci are often located in intergenic regions, so our evolving understanding of the noncoding regulatory regions of the genome are likely to aid in the identification of novel genes that are important for cardiac electrical function and possibly SCD.

Postmortem analysis of cardiovascular deaths in schizophrenia: a 10-year review

Schizophrenia is a devastating mental disorder, associated with mortality rates up to three times higher than those in the general population. This post-mortem study sought to investigate the causes of death in a consecutive series of schizophrenia cases, with a specific focus on cardiovascular disease and sudden death. A 10-year review of autopsies in schizophrenia related-cases performed at the Department of Forensic Medicine in Sydney, Australia was undertaken. Premorbid clinical and demographic information was recorded, as well as the key pathological findings and final cause of death. From 2003 to 2012, there were 19,478 postmortem examinations performed of which 683 (3.5%) were deaths in people with a history of schizophrenia. In these cases, the mean age at death was 51years (range 18-93years), with 43% in the 41-60year age group. Males comprised 67% of cases. Overall, 62% of cases had a BMI≥25kg/m(2), indicating overweight or obese individuals. The three primary causes of death were "cardiovascular" (23%), "suicide" (20%), and "drug toxicity" (17%). In 11% of cases (n=72), no definitive cause of death was found, the so-called "unexplained" cases. In conclusion, patients with schizophrenia have premature mortality. The major contributing factors include cardiovascular diseases, suicide and drug toxicity. The "unexplained" and frequently sudden deaths may suggest underlying cardiac arrhythmias as a cause of death in a subgroup of schizophrenia patients.