The spectrum of epidemiology underlying sudden cardiac death

A universal strategy for constructing high-performance silica-based AIE materials for biomedical application

As an emerging fluorophore, aggregation-induced emission luminogens (AIEgens) have received widespread attention in recent years, but the inherent drawbacks of AIEgens, such as the poor water-solubility and insufficient fluorescence stability in complex environments, restrict their performance in practical applications. Herein, we report a universal strategy based on hydrophobic dendritic mesoporous silica (HMSN) that can integrate different AIE molecules to construct multi-color fluorescent AIE materials. Specifically, HMSN with central radial pores was used as a powerful carrier for direct loading AIE molecules and restricting their intramolecular motions. Due to the pore-domain restriction effect and hydrophobic interaction, the obtained silica-based AIE materials have bright fluorescence with a maximum quantum yield of 68.38%, high colloidal/fluorescence stability, and excellent biosafety. Further, these silica-based AIE materials can be conjugated with functional antibodies to obtain probes with different targetability. After integration with immunomagnetic beads, the prepared detection probes achieved the quantitative detection of cardiac troponin I with the limit of detection (LOD) of 0.508 ng/mL. Overall, the targeting probes stemming from silica-based AIE materials can not only achieve cell-specific imaging, but quantify the number of Jurkat cells (LOD = 270 cells/mL) to further determine the specific etiology of the disease.

APOB and CCL17 as mediators in the protective effect of SGLT2 inhibition against myocardial infarction: Insights from proteome-wide mendelian randomization

AIMS

Sodium-glucose cotransporter 2 (SGLT2) inhibitors offer a novel therapeutic avenue for myocardial infarction (MI). However, the exact nature of this relationship and the underlying mechanisms are not fully understood.

METHODS

Utilizing a two-sample Mendelian Randomization (MR) analysis, we elucidated the causal effects stemming from the inhibition of SGLT2 on MI. Then, The pool of 4907 circulating proteins within the plasma proteome were utilized to explore the mediators of SGLT2 inhibitors on MI. Protein-protein network and enrichment analysis were conducted to clarify the potential mechanism. Finally, employing MR analysis and meta-analysis techniques, we systematically assessed the causal associations between SGLT2 inhibition and coronary heart diseases (CHD).

RESULTS

SGLT2 inhibition (per 1 SD decrement in HbA1c) was associated with reduced risk of MI (odds ratio [OR] = 0.462, [95% CI 0.222, 0.958], P = 0.038). Among 4907 circulating proteins, we identified APOB and CCL17 which were related to both SGLT2 inhibition and MI. Mediation analysis showed evidence of the indirect effect of SGLT2 inhibition on MI through APOB (β = -0.557, 95%CI [-1.098, -0.155]) with a mediated proportion of 72%, and CCL17 (β = -0.176, 95%CI [-0.332, -0.056]) with a mediated proportion of 17%. The meta-analysis result showed that SGLT2 inhibition was associated with a lower risk of CHD.

CONCLUSION

Based on proteome-wide mendelian randomization, APOB and CCL17 were seen as mediators in the protective effect of SGLT2 inhibition against myocardial infarction.

A His bundle pacing protocol for suppressing ventricular arrhythmia maintenance and improving defibrillation efficacy

BACKGROUND

The excitable gap (EG), defined as the excitable tissue between two subsequent wavefronts of depolarization, is critical for maintaining reentry that underlies deadly ventricular arrhythmias. EG in the His-Purkinje Network (HPN) plays an important role in the maintenance of electrical wave reentry that underlies these arrhythmias.

OBJECTIVE

To determine if rapid His bundle pacing (HBP) during reentry reduces the amount of EG in the HPN and ventricular myocardium to suppress reentry maintenance and/or improve defibrillation efficacy.

METHODS

In a virtual human biventricular model, reentry was initiated with rapid line pacing followed by HBP delivered for 3, 6, or 9 s at pacing cycle lengths (PCLs) ranging from 10 to 300 ms (n=30). EG was calculated independently for the HPN and myocardium over each PCL. Defibrillation efficacy was assessed for each PCL by stimulating myocardial surface EG with delays ranging from 0.25 to 9 s (increments of 0.25 s, n=36) after the start of HBP. Defibrillation was successful if reentry terminated within 1 s after EG stimulation. This defibrillation protocol was repeated without HBP. To test the approach under different pathological conditions, all protocols were repeated in the model with right (RBBB) or left (LBBB) bundle branch block.

RESULTS

Compared to without pacing, HBP for >3 seconds reduced average EG in the HPN and myocardium across a broad range of PCLs for the default, RBBB, and LBBB models. HBP >6 seconds terminated reentrant arrhythmia by converting HPN activation to a sinus rhythm behavior in the default (6/30 PCLs) and RBBB (7/30 PCLs) models. Myocardial EG stimulation during HBP increased the number of successful defibrillation attempts by 3%-19% for 30/30 PCLs in the default model, 3%-6% for 14/30 PCLs in the RBBB model, and 3%-11% for 27/30 PCLs in the LBBB model.

CONCLUSION

HBP can reduce the amount of excitable gap and suppress reentry maintenance in the HPN and myocardium. HBP can also improve the efficacy of low-energy defibrillation approaches targeting excitable myocardium. HBP during reentrant arrhythmias is a promising anti-arrhythmic and defibrillation strategy.

German Cardiac Arrest Registry (G-CAR)-results of the pilot phase

BACKGROUND

In Europe, more than 300,000 persons per year experience out-of-hospital cardiac arrest (OHCA). Despite medical progress, only few patients survive with good neurological outcome. For many issues, evidence from randomized trials is scarce. OHCA often occurs for cardiac causes. Therefore, we established the national, prospective, multicentre German Cardiac Arrest Registry (G-CAR). Herein, we describe the first results of the pilot phase.

RESULTS

Over a period of 16 months, 15 centres included 559 consecutive OHCA patients aged ≥ 18 years. The median age of the patients was 66 years (interquartile range 57;75). Layperson resuscitation was performed in 60.5% of all OHCA cases which were not observed by emergency medical services. The initial rhythm was shockable in 46.4%, and 29.1% of patients had ongoing CPR on hospital admission. Main presumed causes of OHCA were acute coronary syndromes (ACS) and/or cardiogenic shock in 54.8%, with ST-elevation myocardial infarction being the most common aetiology (34.6%). In total, 62.9% of the patients underwent coronary angiography; percutaneous coronary intervention (PCI) was performed in 61.4%. Targeted temperature management was performed in 44.5%. Overall in-hospital mortality was 70.5%, with anoxic brain damage being the main presumed cause of death (38.8%). Extracorporeal cardiopulmonary resuscitation (eCPR) was performed in 11.0%. In these patients, the in-hospital mortality rate was 85.2%.

CONCLUSIONS

G-CAR is a multicentre German registry for adult OHCA patients with a focus on cardiac and interventional treatment aspects. The results of the 16-month pilot phase are shown herein. In parallel with further analyses, scaling up of G-CAR to a national level is envisaged. Trial registration ClinicalTrials.gov identifier: NCT05142124.

Emergence of Artificial Intelligence and Machine Learning Models in Sudden Cardiac Arrest: A Comprehensive Review of Predictive Performance and Clinical Decision Support

Sudden cardiac death/sudden cardiac arrest (SCD/SCA) is an increasingly prevalent cause of mortality globally, particularly in individuals with preexisting cardiac conditions. The ambiguous premortem warnings and the restricted interventional window related to SCD account for the complexity of the condition. Current reports suggest SCD to be accountable for 20% of all deaths hence accurately predicting SCD risk is an imminent concern. Traditional approaches for predicting SCA, particularly "track-and-trigger" warning systems have demonstrated considerable inadequacies, including low sensitivity, false alarms, decreased diagnostic liability, reliance on clinician involvement, and human errors. Artificial intelligence (AI) and machine learning (ML) models have demonstrated near-perfect accuracy in predicting SCA risk, allowing clinicians to intervene timely. Given the constraints of current diagnostics, exploring the benefits of AI and ML models in enhancing outcomes for SCA/SCD is imperative. This review article aims to investigate the efficacy of AI and ML models in predicting and managing SCD, particularly targeting accuracy in prediction.

Autopsy of all young sudden death cases is important to increase survival in family members left behind

Sudden cardiac death (SCD) is an important public health problem worldwide, accounting for an estimated 6-20% of total mortality. A significant proportion of SCD is caused by inherited heart disease, especially among the young. An autopsy is crucial to establish a diagnosis of inherited heart disease, allowing for subsequent identification of family members who require cardiac evaluation. Autopsy of cases of unexplained sudden death in the young is recommended by both the European Society of Cardiology and the American Heart Association. Overall autopsy rates, however, have been declining in many countries across the globe, and there is a lack of skilled trained pathologists able to carry out full autopsies. Recent studies show that not all cases of sudden death in the young are autopsied, likely due to financial, administrative, and organizational limitations as well as awareness among police, legal authorities, and physicians. Consequently, diagnoses of inherited heart disease are likely missed, along with the opportunity for treatment and prevention among surviving relatives. This article reviews the evidence for the role of autopsy in sudden death, how the cardiologist should interpret the autopsy-record, and how this can be integrated and implemented in clinical practice. Finally, we identify areas for future research along with potential for healthcare reform aimed at increasing autopsy awareness and ultimately reducing mortality from SCD.

Age and sex-related differences in outcomes of OHCA patients after adjustment for sex-based in-hospital management disparities

OBJECTIVES

Out-of-hospital cardiac arrest (OHCA) survival differences due to sex remain controversial. Previous studies adjusted for prehospital variables, but not sex-based in-hospital management disparities. We aimed to investigate age and sex-related differences in survival outcomes in OHCA patients after adjustment for sex-based in-hospital management disparities.

METHODS

This retrospective observational study used a prospective multicenter OHCA registry to review data of patients from October 2015 to December 2020. The primary outcome was good neurological outcome defined as cerebral performance category score 1 or 2. We performed multivariable logistic regression and restricted cubic spline analysis according to age.

RESULTS

Totally, 8988 patients were analyzed. Women showed poorer prehospital characteristics and received fewer coronary angiography, percutaneous coronary interventions, targeted temperature management, and extracorporeal membrane oxygenation than men. Good neurological outcomes were lower in women than in men (5.8% vs. 12.2%, p < 0.001). After adjustment for age, prehospital variables, and in-hospital management, women were more likely to have good neurological outcomes than men (adjusted odds ratio [aOR] 1.37, 95% confidence interval [CI] 1.07-1.74, p = 0.012). The restricted cubic spline curve showed a reverse sigmoid pattern of adjusted predicted probability of outcomes and dynamic associations of sex and age-based outcomes.

CONCLUSIONS

Women with OHCA were more likely to have good neurological outcome after adjusting for age, prehospital variables, and sex-based in-hospital management disparities. There were non-linear associations between sex and survival outcomes according to age and age-related sex-based differences.

Biomarker Periodic Repolarization Dynamics Indicates Enhanced Risk for Arrhythmias and Sudden Cardiac Death in Myocardial Infarction in Pigs

BACKGROUND

Periodic repolarization dynamics (PRD) is an electrocardiographic biomarker that captures repolarization instability in the low frequency spectrum and is believed to estimate the sympathetic effect on the ventricular myocardium. High PRD indicates an increased risk for postischemic sudden cardiac death (SCD). However, a direct link between PRD and proarrhythmogenic autonomic remodeling has not yet been shown.

METHODS AND RESULTS

We investigated autonomic remodeling in pigs with myocardial infarction (MI)-related ischemic heart failure induced by balloon occlusion of the left anterior descending artery (n=17) compared with pigs without MI (n=11). Thirty days after MI, pigs demonstrated enhanced sympathetic innervation in the infarct area, border zone, and remote left ventricle paralleled by altered expression of autonomic marker genes/proteins. PRD was enhanced 30 days after MI compared with baseline (pre-MI versus post-MI: 1.75±0.30 deg2 versus 3.29±0.79 deg2, P<0.05) reflecting pronounced autonomic alterations on the level of the ventricular myocardium. Pigs with MI-related ventricular fibrillation and SCD had significantly higher pre-MI PRD than pigs without tachyarrhythmias, suggesting a potential role for PRD as a predictive biomarker for ischemia-related arrhythmias (no ventricular fibrillation versus ventricular fibrillation: 1.50±0.39 deg2 versus 3.18±0.53 deg2 [P<0.05]; no SCD versus SCD: 1.67±0.32 deg2 versus 3.91±0.63 deg2 [P<0.01]).

CONCLUSIONS

We demonstrate that ischemic heart failure leads to significant proarrhythmogenic autonomic remodeling. The concomitant elevation of PRD levels in pigs with ischemic heart failure and pigs with MI-related ventricular fibrillation/SCD suggests PRD as a biomarker for autonomic remodeling and as a potential predictive biomarker for ventricular arrhythmias/survival in the context of MI.

Alcohol is neither a risk factor nor a protective factor for sudden cardiac death and/or fatal ventricular arrhythmia: A population-based study with genetic traits and alcohol consumption in the UK Biobank

BACKGROUND

The association between alcohol consumption and the risk of sudden cardiac death and/or fatal ventricular arrhythmia remains controversial.

OBJECTIVE

We analyzed the association between alcohol consumption, genetic traits for alcohol metabolism, and the risk of sudden cardiac death and/or fatal ventricular arrhythmia.

METHODS

We identified 397,164 individuals enrolled between 2006 and 2010 from the UK Biobank database and followed them until 2021. Alcohol consumption was categorized as current nondrinkers (nondrinkers and ex-drinkers), mild drinkers, moderate drinkers, or heavy drinkers. Genetic traits of alcohol metabolism were stratified according to the polygenic risk score tertiles. The primary and secondary outcomes were a composite of sudden cardiac death and fatal ventricular arrhythmia as well as their individual components.

RESULTS

During follow-up (median 12.5 years), 3543 cases (0.89%) of clinical outcomes occurred. Although mild, moderate, and heavy drinkers showed deceased risks of outcomes compared with current nondrinkers, there was no prognostic difference among nondrinkers, mild drinkers, moderate drinkers, and heavy drinkers. Ex-drinkers showed an increased risk in univariate analysis, but the significance was attenuated after adjusting covariates (hazard ratio 1.19; 95% confidence interval 0.94-1.50). As a continuous variable, alcohol consumption was not associated with clinical outcomes (hazard ratio 1.01; 95% confidence interval 0.99-1.02). Consistent with these findings, there was no association between genetic traits for alcohol metabolism and the risk of clinical outcomes.

CONCLUSION

Alcohol consumption was neither a protective factor nor a risk factor for sudden cardiac death or fatal ventricular arrhythmia. Genetic traits of alcohol metabolism were not associated with the clinical prognosis.

Sleep apnea, the risk of out-of-hospital cardiac arrest, and potential benefits of continuous positive airway pressure therapy: A nationwide study

OBJECTIVE

Patients with sleep apnea (SA) are at increased cardiovascular risk. However, little is known about the risk of out-of-hospital cardiac arrest (OHCA) in patients with SA. Therefore, we studied the relation between SA patients who did and did not receive continuous positive airway pressure (CPAP) therapy with OHCA in the general population.

METHODS

Using nationwide databases, we conducted a nested case-control study with OHCA-cases of presumed cardiac causes and age/sex/OHCA-date matched non-OHCA-controls from the general population. Conditional logistic regression models with adjustments for well-known OHCA risk factors were performed to generate odds ratio (OR) of OHCA comparing patients with SA receiving and not receiving CPAP therapy with individuals without SA.

RESULTS

We identified 46,578 OHCA-cases and 232,890 matched non-OHCA-controls [mean: 71 years, 68.8% men]. Compared to subjects without SA, having SA without CPAP therapy was associated with increased odds of OHCA after controlling for relevant confounders (OR:1.20, 95%-Cl:1.06-1.36), while having SA with CPAP therapy was not associated with OHCA (OR:1.04, 95%-Cl:0.93-1.36). Regardless of CPAP therapy, age and sex did not significantly influence our findings. Our findings were confirmed in: (I) patients with neither ischemic heart disease nor heart failure (untreated SA, OR:1.24, 95%-CI:1.04-1.47; SA with CPAP, OR:1.08, 95%-CI:0.93-1.25); and (II) in patients without cardiovascular disease (untreated SA, OR:1.33, 95%-CI:1.07-1.65; SA with CPAP, OR:1.14, 95%-CI:0.94-1.39).

CONCLUSION

SA not treated with CPAP was associated with OHCA, while no increased risk of OHCA was found for SA patients treated with CPAP.

Artificial intelligence for ventricular arrhythmia capability using ambulatory electrocardiograms

Aims

European and American clinical guidelines for implantable cardioverter defibrillators are insufficiently accurate for ventricular arrhythmia (VA) risk stratification, leading to significant morbidity and mortality. Artificial intelligence offers a novel risk stratification lens through which VA capability can be determined from the electrocardiogram (ECG) in normal cardiac rhythm. The aim of this study was to develop and test a deep neural network for VA risk stratification using routinely collected ambulatory ECGs.

Methods and results

A multicentre case-control study was undertaken to assess VA-ResNet-50, our open source ResNet-50-based deep neural network. VA-ResNet-50 was designed to read pyramid samples of three-lead 24 h ambulatory ECGs to decide whether a heart is capable of VA based on the ECG alone. Consecutive adults with VA from East Midlands, UK, who had ambulatory ECGs as part of their NHS care between 2014 and 2022 were recruited and compared with all comer ambulatory electrograms without VA. Of 270 patients, 159 heterogeneous patients had a composite VA outcome. The mean time difference between the ECG and VA was 1.6 years (⅓ ambulatory ECG before VA). The deep neural network was able to classify ECGs for VA capability with an accuracy of 0.76 (95% confidence interval 0.66-0.87), F1 score of 0.79 (0.67-0.90), area under the receiver operator curve of 0.8 (0.67-0.91), and relative risk of 2.87 (1.41-5.81).

Conclusion

Ambulatory ECGs confer risk signals for VA risk stratification when analysed using VA-ResNet-50. Pyramid sampling from the ambulatory ECGs is hypothesized to capture autonomic activity. We encourage groups to build on this open-source model.

Question

Can artificial intelligence (AI) be used to predict whether a person is at risk of a lethal heart rhythm, based solely on an electrocardiogram (an electrical heart tracing)?

Findings

In a study of 270 adults (of which 159 had lethal arrhythmias), the AI was correct in 4 out of every 5 cases. If the AI said a person was at risk, the risk of lethal event was three times higher than normal adults.

Meaning

In this study, the AI performed better than current medical guidelines. The AI was able to accurately determine the risk of lethal arrhythmia from standard heart tracings for 80% of cases over a year away-a conceptual shift in what an AI model can see and predict. This method shows promise in better allocating implantable shock box pacemakers (implantable cardioverter defibrillators) that save lives.

Sudden Cardiac Death in the Young: State-of-the-Art Review in Molecular Autopsy

Sudden cardiac death (SCD) is defined as unexpected death due to a cardiac cause that occurs rapidly. Despite the identification of prevention strategies, SCD remains a serious public health problem worldwide, accounting for 15-20% of all deaths, and is therefore a challenge for modern medicine, especially when it affects young people. Sudden cardiac death in young people affects the population aged ≤ 35 years, including athletes and non-athletes, and it is due to various hereditary and non-hereditary causes. After an autopsy, if the cause remains unknown, it is called sudden unexplained death, often attributable to genetic causes. In these cases, molecular autopsy-post-mortem genetic testing-is essential to facilitate diagnostic and therapeutic pathways and/or the monitoring of family members of the cases. This review aims to elaborate on cardiac disorders marked by genetic mutations, necessitating the post-mortem genetic investigation of the deceased for an accurate diagnosis in order to facilitate informed genetic counseling and to implement preventive strategies for family members of the cases.

Prognostic significance of beat-to-beat variability of spatial heterogeneity of repolarization analyzed from a 5-minute resting electrocardiogram in coronary artery disease

BACKGROUND

Data on the prognostic significance of temporal variability of spatial heterogeneity of electrocardiographic repolarization in coronary artery disease (CAD) are limited.

OBJECTIVE

The purpose of this study was to evaluate the prognostic value of temporal variability of T-wave morphology analyzed from a 5-minute resting electrocardiogram in CAD.

METHODS

The standard deviation (SD) of T-wave morphology dispersion (TMD-SD) and the SD of total cosine R-to-T were analyzed on a beat-to-beat basis from a 5-minute period of the standard resting 12-lead electrocardiogram obtained before the clinical stress test in 1702 patients with angiographically verified CAD and well-preserved left ventricular function.

RESULTS

During an average of 8.7 ± 2.2 years of follow-up, 60 patients experienced sudden cardiac death/arrest (SCD/SCA) (3.5%), 69 patients nonsudden cardiac death (NSCD) (4.1%), and 161 patients noncardiac death (9.5%). TMD-SD was significantly higher in patients who experienced SCD/SCA than in other patients (1.72 ± 2.00 vs 1.12 ± 1.75; P = .01) and higher in patients who succumbed to NSCD than in other patients (1.57 ± 1.74 vs 1.12 ± 1.76; P = .04), but it did not differ significantly between patients who experienced noncardiac death and those without such an event (1.16 ± 1.42 vs 1.14 ± 1.79; P = .86). In the Cox multivariable hazards model, TMD-SD retained its significant association with the risk of SCD/SCA (hazard ratio 1.119; 95% confidence interval 1.015-1.233; P = .024) but not with the risk of NSCD (hazard ratio 1.089; 95% confidence interval 0.983-1.206; P = .103).

CONCLUSION

TMD-SD is independently associated with the long-term risk of SCD/SCA in patients with CAD.

Ethical use of artificial intelligence to prevent sudden cardiac death: an interview study of patient perspectives

BACKGROUND

The emergence of artificial intelligence (AI) in medicine has prompted the development of numerous ethical guidelines, while the involvement of patients in the creation of these documents lags behind. As part of the European PROFID project we explore patient perspectives on the ethical implications of AI in care for patients at increased risk of sudden cardiac death (SCD).

AIM

Explore perspectives of patients on the ethical use of AI, particularly in clinical decision-making regarding the implantation of an implantable cardioverter-defibrillator (ICD).

METHODS

Semi-structured, future scenario-based interviews were conducted among patients who had either an ICD and/or a heart condition with increased risk of SCD in Germany (n = 9) and the Netherlands (n = 15). We used the principles of the European Commission's Ethics Guidelines for Trustworthy AI to structure the interviews.

RESULTS

Six themes arose from the interviews: the ability of AI to rectify human doctors' limitations; the objectivity of data; whether AI can serve as second opinion; AI explainability and patient trust; the importance of the 'human touch'; and the personalization of care. Overall, our results reveal a strong desire among patients for more personalized and patient-centered care in the context of ICD implantation. Participants in our study express significant concerns about the further loss of the 'human touch' in healthcare when AI is introduced in clinical settings. They believe that this aspect of care is currently inadequately recognized in clinical practice. Participants attribute to doctors the responsibility of evaluating AI recommendations for clinical relevance and aligning them with patients' individual contexts and values, in consultation with the patient.

CONCLUSION

The 'human touch' patients exclusively ascribe to human medical practitioners extends beyond sympathy and kindness, and has clinical relevance in medical decision-making. Because this cannot be replaced by AI, we suggest that normative research into the 'right to a human doctor' is needed. Furthermore, policies on patient-centered AI integration in clinical practice should encompass the ethics of everyday practice rather than only principle-based ethics. We suggest that an empirical ethics approach grounded in ethnographic research is exceptionally well-suited to pave the way forward.

Cardiac MRI after Sudden Cardiac Arrest: A Systematic Review

Purpose To perform a systematic review to assess the diagnostic and prognostic value of cardiac MRI after sudden cardiac arrest (SCA). Materials and Methods PubMed and Cochrane Library databases were systematically searched for studies investigating cardiac MRI after SCA in adult patients (≥18 years of age). The time frame of the encompassed studies spans from January 2012 to January 2023. The study protocol was preregistered in OSF Registries (www.osf.io/nxaev), and the systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The quality of the included studies was evaluated using the Newcastle-Ottawa quality assessment scale. Results Fourteen studies involving 1367 individuals, 1257 (91.9%) of whom underwent cardiac MRI, were included. Inconsistent findings were reported on the diagnostic value of cardiac MRI-specific findings. The included studies demonstrated the following main findings: (a) cardiac MRI led to a new or alternative diagnosis in patients with SCA; (b) cardiac MRI identified pathologic or arrhythmogenic substrates; (c) cardiac MRI helped detect myocardial edema (potentially reversible); (d) cardiac MRI provided evidence for the occurrence of adverse events; and (e) functional markers or ventricular dimensions were considered prognostically relevant in a few studies. Relevant challenges in this systematic review were the lack of comparators and reference standards relative to cardiac MRI as the index test and patient selection bias. Conclusion Cardiac MRI following SCA can contribute to the diagnostic process and offer supplementary information essential for treatment planning. Limitations of the review include studies with insufficient comparators and potential bias in patient selection. Systematic review registration link: osf.io/nxaev Keywords: Cardiac MRI, Cardiovascular Disease, Cardiomyopathy, Ischemia, Myocardial Edema, Sudden Cardiac Arrest © RSNA, 2024.

Clinical Decision Support Requirements for Ventricular Tachycardia Diagnosis Within the Frameworks of Knowledge and Practice: Survey Study

BACKGROUND

Ventricular tachycardia (VT) diagnosis is challenging due to the similarity between VT and some forms of supraventricular tachycardia, complexity of clinical manifestations, heterogeneity of underlying diseases, and potential for life-threatening hemodynamic instability. Clinical decision support systems (CDSSs) have emerged as promising tools to augment the diagnostic capabilities of cardiologists. However, a requirements analysis is acknowledged to be vital for the success of a CDSS, especially for complex clinical tasks such as VT diagnosis.

OBJECTIVE

The aims of this study were to analyze the requirements for a VT diagnosis CDSS within the frameworks of knowledge and practice and to determine the clinical decision support (CDS) needs.

METHODS

Our multidisciplinary team first conducted semistructured interviews with seven cardiologists related to the clinical challenges of VT and expected decision support. A questionnaire was designed by the multidisciplinary team based on the results of interviews. The questionnaire was divided into four sections: demographic information, knowledge assessment, practice assessment, and CDS needs. The practice section consisted of two simulated cases for a total score of 10 marks. Online questionnaires were disseminated to registered cardiologists across China from December 2022 to February 2023. The scores for the practice section were summarized as continuous variables, using the mean, median, and range. The knowledge and CDS needs sections were assessed using a 4-point Likert scale without a neutral option. Kruskal-Wallis tests were performed to investigate the relationship between scores and practice years or specialty.

RESULTS

Of the 687 cardiologists who completed the questionnaire, 567 responses were eligible for further analysis. The results of the knowledge assessment showed that 383 cardiologists (68%) lacked knowledge in diagnostic evaluation. The overall average score of the practice assessment was 6.11 (SD 0.55); the etiological diagnosis section had the highest overall scores (mean 6.74, SD 1.75), whereas the diagnostic evaluation section had the lowest scores (mean 5.78, SD 1.19). A majority of cardiologists (344/567, 60.7%) reported the need for a CDSS. There was a significant difference in practice competency scores between general cardiologists and arrhythmia specialists (P=.02).

CONCLUSIONS

There was a notable deficiency in the knowledge and practice of VT among Chinese cardiologists. Specific knowledge and practice support requirements were identified, which provide a foundation for further development and optimization of a CDSS. Moreover, it is important to consider clinicians' specialization levels and years of practice for effective and personalized support.

Regional disparities and risk factors of mortality among patients at high risk of sudden cardiac death in emerging countries: a nonrandomized controlled trial

BACKGROUND

Comprehensive data on patients at high risk of sudden cardiac death (SCD) in emerging countries are lacking. The aim was to deepen our understanding of the SCD phenotype and identify risk factors for death among patients at high risk of SCD in emerging countries.

METHODS

Patients who met the class I indication for implantable cardioverter-defibrillator (ICD) implantation according to guideline recommendations in 17 countries and regions underrepresented in previous trials were enrolled. Countries were stratified by the WHO regional classification. Patients were or were not implanted with an ICD at their discretion. The outcomes were all-cause mortality and SCD.

RESULTS

We enrolled 4222 patients, and 3889 patients were included in the analysis. The mean follow-up period was 21.6 ± 10.2 months. There were 433 (11.1%) instances of all-cause mortality and 117 (3.0%) cases of SCD. All-cause mortality was highest in primary prevention (PP) patients from Southeast Asia and secondary prevention (SP) patients from the Middle East and Africa. The SCD rates among PP and SP patients were both highest in South Asia. Multivariate Cox regression modelling demonstrated that in addition to the independent predictors identified in previous studies, both geographic region and ICD use were associated with all-cause mortality in patients with high SCD risk. Primary prophylactic ICD implantation was associated with a 36% (HR = 0.64, 95% CI 0.531-0.802, p < 0.0001) lower all-cause mortality risk and an 80% (HR = 0.20, 95% CI = 0.116-0.343, p < 0.0001) lower SCD risk.

CONCLUSIONS

There was significant heterogeneity among patients with high SCD risk in emerging countries. The influences of geographic regions on patient characteristics and outcomes were significant. Improvement in increasing ICD utilization and uptake of guideline-directed medical therapy in emerging countries is urgent.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02099721.

TBX5 genetic variants and SCD-CAD susceptibility: insights from Chinese Han cohorts

Background

The prevention and prediction of sudden cardiac death (SCD) present persistent challenges, prompting exploration into common genetic variations for potential insights. T-box 5 (TBX5), a critical cardiac transcription factor, plays a pivotal role in cardiovascular development and function. This study systematically examined variants within the 500-bp region downstream of the TBX5 gene, focusing on their potential impact on susceptibility to SCD associated with coronary artery disease (SCD-CAD) in four different Chinese Han populations.

Methods

In a comprehensive case-control analysis, we explored the association between rs11278315 and SCD-CAD susceptibility using a cohort of 553 controls and 201 SCD-CAD cases. Dual luciferase reporter assays and genotype-phenotype correlation studies using human cardiac tissue samples as well as integrated in silicon analysis were applied to explore the underlining mechanism.

Result

Binary logistic regression results underscored a significantly reduced risk of SCD-CAD in individuals harboring the deletion allele (odds ratio = 0.70, 95% CI [0.55-0.88], p = 0.0019). Consistent with the lower transcriptional activity of the deletion allele observed in dual luciferase reporter assays, genotype-phenotype correlation studies on human cardiac tissue samples affirmed lower expression levels associated with the deletion allele at both mRNA and protein levels. Furthermore, our investigation revealed intriguing insights into the role of rs11278315 in TBX5 alternative splicing, which may contribute to alterations in its ultimate functional effects, as suggested by sQTL analysis. Gene ontology analysis and functional annotation further underscored the potential involvement of TBX5 in alternative splicing and cardiac-related transcriptional regulation.

Conclusions

In summary, our current dataset points to a plausible correlation between rs11278315 and susceptibility to SCD-CAD, emphasizing the potential of rs11278315 as a genetic risk marker for aiding in molecular diagnosis and risk stratification of SCD-CAD.

Circadian Regulation of Cardiac Arrhythmias and Electrophysiology

Circadian rhythms in physiology and behavior are ≈24-hour biological cycles regulated by internal biological clocks (ie, circadian clocks) that optimize organismal homeostasis in response to predictable environmental changes. These clocks are present in virtually all cells in the body, including cardiomyocytes. Many decades ago, clinicians and researchers became interested in studying daily patterns of triggers for sudden cardiac death, the incidence of sudden cardiac death, and cardiac arrhythmias. This review highlights historical and contemporary studies examining the role of day/night rhythms in the timing of cardiovascular events, delves into changes in the timing of these events over the last few decades, and discusses cardiovascular disease-specific differences in the timing of cardiovascular events. The current understanding of the environmental, behavioral, and circadian mechanisms that regulate cardiac electrophysiology is examined with a focus on the circadian regulation of cardiac ion channels and ion channel regulatory genes. Understanding the contribution of environmental, behavioral, and circadian rhythms on arrhythmia susceptibility and the incidence of sudden cardiac death will be essential in developing future chronotherapies.

Arrhythmias and Sudden Cardiac Death

Ventricular tachyarrhythmias remain a major cause of sudden cardiac arrest (SCA) that leads to sudden cardiac death (SCD). Primary prevention strategies to prevent SCD include promoting a healthy lifestyle, following United States Preventive Service Task Force recommendations related to cardiovascular disease, and controlling comorbid conditions. For a patient experiencing SCA, early cardiopulmonary resuscitation and defibrillation should be performed. Implantable cardioverter defibrillators are more effective at secondary prevention compared with drug therapy but medications such as amiodarone, beta-blockers, and sotalol may be helpful adjuncts to reduce the risk of SCD or improve a patient's symptoms (eg, palpitations and inappropriate defibrillator shocks).

Incidence of Sudden Cardiac Death in Low- and Middle-Income Countries: A Systematic Review of Cohort Studies

Sudden cardiac death (SCD) is a leading cause of mortality worldwide and, in recent years, has become an urgent public health concern in low- and middle-income countries (LMICs). Data from LMICs, however, remains limited. As such, the aim of this article is to systematically review the current literature on the incidence of SCD in LMICs to inform policymakers and identify potential research gaps. A search of PubMed and Embase was utilized to capture the targeted condition, outcome, and setting. Only peer-reviewed cohort studies in LMICs reporting SCD incidence estimates in the general population of individuals aged ≥1 year were eligible for selection. Papers providing incidence data for specific types of SCD, including sudden coronary death or death from sudden cardiac arrest, were also included. After deduplication, 1941 citations were identified and screened. Seven studies representing four countries-Cameroon, China, India, and Iran-met the criteria for inclusion and were considered in our analysis. The crude incidence rate for SCD ranged from 19.9 to 190 cases per 100,000 person-years, while age-adjusted rates ranged from 33.6 to 230 cases per 100,000 person-years. There was notable variability in methods utilized to ascertain SCD cases. These findings suggest that the incidence of all-cause SCD in LMICs and may exceed that of high-income countries; however, observed disparities may be partly attributable to differences in case ascertainment methods. Additional research is needed to better understand the true incidence of SCD in developing countries. It is crucial that future studies across regions utilize standard diagnostic criteria and methodology for identifying SCD, which would provide a framework by which to compare outcomes between settings.

Ventricular arrhythmia inducibility in porcine infarct model after stereotactic body radiation therapy

BACKGROUND

Ventricular arrhythmia (VA) is the primary mechanism of sudden death in patients with structural heart disease. Cardiac stereotactic body radiation therapy (SBRT) delivered to the scar in the left ventricle significantly reduces the burden of VA.

OBJECTIVE

The goal of this study was to investigate the impact of SBRT on scar morphology and VA inducibility in a porcine infarct model.

METHODS

Myocardial infarction (MI) was created in 10 Yorkshire pigs involving the left anterior descending artery territory. Cardiac positron emission tomography and computed tomography were performed for targeted SBRT. Alternative pigs received SBRT at 25 Gy in a single fraction. The terminal experiment included endocardial mapping, programmed ventricular stimulation, and tissue harvesting.

RESULTS

Of the 10 pigs infarcted, 2 died prematurely after MI and 8 (4 MI and 4 MI+SBRT) survived. Mean time from MI to SBRT was 48 ± 12 days, and mean time from SBRT to harvest was 32 ± 12 days. Scar was localized on intracardiac mapping in all pigs, and the scar was denser in the MI+SBRT compared with the MI-only group (33% ± 20% vs 14% ± 11%; P = .07). All 4 MI pigs had inducible VA during programmed stimulation, whereas only 1 of 4 pigs had inducible VA in the MI+SBRT arm (100% vs 25%; P = .07). No myocardial fibrosis was seen in the remote areas in either group.

CONCLUSION

SBRT reduced VA inducibility in pigs with scarring after MI. Endocardial mapping revealed denser scar in pigs receiving SBRT compared with those that did not, suggesting that SBRT suppresses VA inducibility through better scar homogenization.

Impact of Updating the Cardiopulmonary Resuscitation Guidelines on Out-of-Hospital Shockable Cardiac Arrest: A Population-Based Cohort Study in Japan

BACKGROUND

International consensus on cardiopulmonary resuscitation (CPR) and emergency cardiovascular care science and treatment recommendations (CoSTR) have reported updates on CPR maneuvers every 5 years since 2000. However, few national population-based studies have investigated the comprehensive effectiveness of those updates for out-of-hospital cardiac arrest due to shockable rhythms. The primary objective of the present study was to determine whether CPR based on CoSTR 2005 or 2010 was associated with improved outcomes in Japan, as compared with CPR based on Guidelines 2000.

METHODS AND RESULTS

From the All-Japan Utstein Registry between 2005 and 2015, we included 73 578 adults who had shockable out-of-hospital cardiac arrest witnessed by bystanders or emergency medical service responders. The study outcomes over an 11-year period were compared between 2005 of the Guidelines 2000 era, from 2006 to 2010 of the CoSTR 2005 era, and from 2011 to 2015 of the CoSTR 2010 era. In the bystander-witnessed group, the adjusted odds ratios for favorable neurological outcomes at 30 days after out-of-hospital cardiac arrest by enrollment year increased year by year (1.19 in 2006, and 3.01 in 2015). Similar results were seen in the emergency medical service responder-witnessed group and several subgroups.

CONCLUSIONS

Compared with CPR maneuvers for shockable out-of-hospital cardiac arrest recommended in the Guidelines 2000, CPR maneuver updates in CoSTR 2005 and 2010 were associated with improved neurologically intact survival year by year in Japan. Increased public awareness and greater dissemination of basic life support may be responsible for the observed improvement in outcomes.

REGISTRATION

URL: https://www.umin.ac.jp/ctr/; Unique identifier: 000009918.

Forensic significance of intracardiac expressions of Nrf2 in acute myocardial ischemia

When exposed to oxidative and electrophilic stress, a protective antioxidant response is initiated by nuclear factor erythroid 2-related factor 2 (Nrf2). However, the extent of its importance in the forensic diagnosis of acute ischemic heart diseases (AIHD), such as myocardial infarction (MI), remains uncertain. On the other hand, immunohistochemical analyses of fibronectin (FN) and the terminal complement complex (C5b-9) prove valuable in identifying myocardial ischemia that precedes necrosis during the postmortem diagnosis of sudden cardiac death (SCD). In this study, we investigated the immunohistochemical levels of Nrf2, FN, and C5b-9 in human cardiac samples to explore their forensic relevance for the identification of acute cardiac ischemia. Heart samples were obtained from 25 AIHD cases and 39 non-AIHD cases as controls. Nrf2 was localized in the nuclei of cardiomyocytes, while FN and C5b-9 were detected in the myocardial cytoplasm. The number of intranuclear Nrf2 positive signals in cardiomyocytes increased in AIHD cases compared to control cases. Additionally, the grading of positive portions of cardiac FN and C5b-9 in the myocardium was also significantly enhanced in AIHD, compared to controls. Collectively, these results indicate that the immunohistochemical investigation of Nrf2 combined with FN, and/or C5b-9 holds the potential for identifying early-stage myocardial ischemic lesions in cases of SCD.

Use of Raman spectroscopy to study rat lung tissues for distinguishing asphyxia from sudden cardiac death

Determining asphyxia as the cause of death is crucial but is based on an exclusive strategy because it lacks sensitive and specific morphological characteristics in forensic practice. In some cases where the deceased has underlying heart disease, differentiation between asphyxia and sudden cardiac death (SCD) as the primary cause of death can be challenging. Herein, Raman spectroscopy was employed to detect pulmonary biochemical differences to discriminate asphyxia from SCD in rat models. Thirty-two rats were used to build asphyxia and SCD models, with lung samples collected immediately or 24 h after death. Twenty Raman spectra were collected for each lung sample, and 640 spectra were obtained for further data preprocessing and analysis. The results showed that different biochemical alterations existed in the lung tissues of the rats that died from asphyxia and SCD and could be used to distinguish between the two causes of death. Moreover, we screened and used 8 of the 11 main differential spectral features that maintained their significant differences at 24 h after death to successfully determine the cause of death, even with decomposition and autolysis. Eventually, seven prevalent machine learning classification algorithms were employed to establish classification models, among which the support vector machine exhibited the best performance, with an area under the curve value of 0.9851 in external validation. This study shows the promise of Raman spectroscopy combined with machine learning algorithms to investigate differential biochemical alterations originating from different deaths to aid determining the cause of death in forensic practice.

Primary Electrical Heart Disease-Principles of Pathophysiology and Genetics

Primary electrical heart diseases, often considered channelopathies, are inherited genetic abnormalities of cardiomyocyte electrical behavior carrying the risk of malignant arrhythmias leading to sudden cardiac death (SCD). Approximately 54% of sudden, unexpected deaths in individuals under the age of 35 do not exhibit signs of structural heart disease during autopsy, suggesting the potential significance of channelopathies in this group of age. Channelopathies constitute a highly heterogenous group comprising various diseases such as long QT syndrome (LQTS), short QT syndrome (SQTS), idiopathic ventricular fibrillation (IVF), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and early repolarization syndromes (ERS). Although new advances in the diagnostic process of channelopathies have been made, the link between a disease and sudden cardiac death remains not fully explained. Evolving data in electrophysiology and genetic testing suggest previously described diseases as complex with multiple underlying genes and a high variety of factors associated with SCD in channelopathies. This review summarizes available, well-established information about channelopathy pathogenesis, genetic basics, and molecular aspects relative to principles of the pathophysiology of arrhythmia. In addition, general information about diagnostic approaches and management is presented. Analyzing principles of channelopathies and their underlying causes improves the understanding of genetic and molecular basics that may assist general research and improve SCD prevention.

Optimization of a cardiomyocyte model illuminates role of increased INa,L in repolarization reserve

Cardiac ion currents may compensate for each other when one is compromised by a congenital or drug-induced defect. Such redundancy contributes to a robust repolarization reserve that can prevent the development of lethal arrhythmias. Most efforts made to describe this phenomenon have quantified contributions by individual ion currents. However, it is important to understand the interplay between all major ion-channel conductances, as repolarization reserve is dependent on the balance between all ion currents in a cardiomyocyte. Here, a genetic algorithm was designed to derive profiles of nine ion-channel conductances that optimize repolarization reserve in a mathematical cardiomyocyte model. Repolarization reserve was quantified using a previously defined metric, repolarization reserve current, i.e., the minimum constant current to prevent normal action potential repolarization in a cell. The optimization improved repolarization reserve current up to 84% compared to baseline in a human adult ventricular myocyte model and increased resistance to arrhythmogenic insult. The optimized conductance profiles were not only characterized by increased repolarizing current conductances but also uncovered a previously unreported behavior by the late sodium current. Simulations demonstrated that upregulated late sodium increased action potential duration, without compromising repolarization reserve current. The finding was generalized to multiple models. Ultimately, this computational approach, in which multiple currents were studied simultaneously, illuminated mechanistic insights into how the metric's magnitude could be increased and allowed for the unexpected role of late sodium to be elucidated.NEW & NOTEWORTHY Genetic algorithms are typically used to fit models or extract desired parameters from data. Here, we use the tool to produce a ventricular cardiomyocyte model with increased repolarization reserve. Since arrhythmia mitigation is dependent on multiple cardiac ion-channel conductances, study using a comprehensive, unbiased, and systems-level approach is important. The use of this optimization strategy allowed us to find robust profiles that illuminated unexpected mechanistic determinants of key ion-channel conductances in repolarization reserve.

Cardiac Catheterization Laboratory Management of the Comatose Adult Patient With an Out-of-Hospital Cardiac Arrest: A Scientific Statement From the American Heart Association

Out-of-hospital cardiac arrest is a leading cause of death, accounting for ≈50% of all cardiovascular deaths. The prognosis of such individuals is poor, with <10% surviving to hospital discharge. Survival with a favorable neurologic outcome is highest among individuals who present with a witnessed shockable rhythm, received bystander cardiopulmonary resuscitation, achieve return of spontaneous circulation within 15 minutes of arrest, and have evidence of ST-segment elevation on initial ECG after return of spontaneous circulation. The cardiac catheterization laboratory plays an important role in the coordinated Chain of Survival for patients with out-of-hospital cardiac arrest. The catheterization laboratory can be used to provide diagnostic, therapeutic, and resuscitative support after sudden cardiac arrest from many different cardiac causes, but it has a unique importance in the treatment of cardiac arrest resulting from underlying coronary artery disease. Over the past few years, numerous trials have clarified the role of the cardiac catheterization laboratory in the management of resuscitated patients or those with ongoing cardiac arrest. This scientific statement provides an update on the contemporary approach to managing resuscitated patients or those with ongoing cardiac arrest.

Seasonal Variation in Sudden Cardiac Death: Insights from a Large United Kingdom Registry

BACKGROUND

Sudden cardiac death (SCD) is relatively common and may occur in apparently healthy individuals. The role of seasonal variation as a risk factor for SCD is poorly understood. The aim of this study was to investigate whether SCD exhibits a predilection for specific seasons.

METHODS

We reviewed a database of 4751 cases of SCD (mean age 38 ± 17 years) referred to our Center for Cardiac Pathology at St George's University of London between 2000 and 2018. Clinical information was obtained from referring coroners who were asked to complete a detailed questionnaire. All cases underwent macroscopic and histological evaluation of the heart, by expert cardiac pathologists.

RESULTS

SCD was more common during winter (26%) and rarer during summer (24%), p = 0.161. Significant seasonal variation was not observed among cases of sudden arrhythmic death syndrome (SADS, 2910 cases) in which the heart is structurally normal. In contrast, a significant difference in seasonal distribution among decedents exhibiting cardiac structural abnormalities at the post-mortem examination (n = 1841) was observed. In this subgroup, SCDs occurred more frequently during winter (27 %) compared to summer (22%) (p = 0.007). In cases diagnosed with a myocardial disease (n = 1399), SCD was most common during the winter (27%) and least common during the summer (22%) (p = 0.027).

CONCLUSIONS

While SADS occurs throughout the year with no seasonal variation, SCD due to structural heart disease appears to be more common during the winter. Bio-meteorological factors may be potential triggers of SCD in individuals with an underlying structural cardiac abnormality.

Incidence and Long-Term Outcomes of Acute Myocardial Infarction Among Survivors of Out-of-Hospital Cardiac Arrest

BACKGROUND

Despite the increasing long-term survival after out-of-hospital cardiac arrest (OHCA), the risk of subsequent acute myocardial infarction (AMI) remains poorly understood. We aimed to determine the incidence, predictors, and long-term outcomes of AMI among survivors of OHCA.

METHODS AND RESULTS

We assembled a retrospective cohort of 882 patients with OHCA who survived to 30 days or discharge from the hospital between 2010 and 2019. Survivors of OHCA had an increased risk of subsequent AMI, defined as AMI occurring 30 days after index OHCA or following discharge from the hospital after OHCA, compared with the general population when matched for age and sex (standardized incidence ratio, 4.64 [95% CI, 3.52-6.01]). Age-specific risks of subsequent AMI for men (standardized incidence ratio, 3.29 [95% CI, 2.39-4.42]) and women (standardized incidence ratio, 6.15 [95% CI, 3.27-10.52]) were significantly increased. A total of 7.2%, 8.3%, and 14.3% of survivors of OHCA had a subsequent AMI at 3 years, 5 years, and end of follow-up, respectively. Age at OHCA (hazard ratio [HR], 1.04 [95% CI, 1.02-1.06]) and past medical history of prior AMI, defined as any AMI preceding or during the index OHCA event (HR, 1.84 [95% CI, 1.05-3.22]), were associated with subsequent AMI, while an initial shockable rhythm was not (HR, 1.00 [95% CI, 0.52-1.94]). Survivors of OHCA with subsequent AMI had a higher risk of death (HR, 1.58 [95% CI, 1.12-2.22]) than those without.

CONCLUSIONS

Survivors of OHCA are at an increased risk of subsequent AMI compared with the general population. Prior AMI, but not an initial shockable rhythm, increases this risk, while subsequent AMI predicts death. Preventive measures for AMI including cardiovascular risk factor control and revascularization may thus improve outcomes in selected patients with cardiac pathogenesis.

Mortality trends, disparities, and social vulnerability in cardiac arrest mortality in the young: A cross-sectional analysis

BACKGROUND

Cardiac arrest (CA) is a leading cause of death in the United States (US). Social determinants of health may impact CA outcomes. We aimed to assess mortality trends, disparities, and the influence of the social vulnerability index (SVI) on CA outcomes in the young.

METHODS

We conducted a cross-sectional analysis of age-adjusted mortality rates (AAMRs) related to CA in the United States from the Years 1999 to 2020 in individuals aged 35 years and younger. Data were obtained from death certificates and analyzed using log-linear regression models. We examined disparities in mortality rates based on demographic variables. We also explored the impact of the SVI on CA mortality.

RESULTS

A total of 4792 CA deaths in the young were identified. Overall AAMR decreased from 0.20 in 1999 to 0.14 in 2020 with an average annual percentage change of -1.3% (p = .001). Black (AAMR: 0.30) and male populations (AAMR: 0.14) had higher AAMR compared with White (AAMR: 0.11) and female (AAMR: 0.11) populations, respectively. Nonmetropolitan (AAMR: 0.29) and Southern (AAMR: 0.26) regions were also impacted by higher AAMR compared with metropolitan (AAMR: 0.11) and other US census regions, respectively. A higher SVI was associated with greater mortality risks related to CA (risk ratio: 1.82 [95% CI, 1.77-1.87]).

CONCLUSIONS

Our analysis of CA in the young revealed disparities based on demographics, with a decline in AAMR from 1999 to 2020. There is a correlation between a higher SVI and increased CA mortality risk, highlighting the importance of targeted interventions to address these disparities effectively.

Mechanical Support Strategies for High-Risk Procedures in the Invasive Cardiac Catheterization Laboratory: A State-of-the-Art Review

Thanks to advancements in percutaneous cardiac interventions, an expanding patient population now qualifies for treatment through percutaneous endovascular procedures. High-risk interventions far exceed coronary interventions and include transcatheter aortic valve replacement, endovascular management of acute pulmonary embolism and ventricular tachycardia ablation. Given the frequent impairment of ventricular function in these patients, frequently deteriorating during percutaneous interventions, it is hypothesized that mechanical ventricular support may improve periprocedural survival and subsequently patient outcome. In this narrative review, we aimed to provide the relevant evidence found for the clinical use of percutaneous mechanical circulatory support (pMCS). We searched the Pubmed database for articles related to pMCS and to pMCS and invasive cath lab procedures. The articles and their references were evaluated for relevance. We provide an overview of the clinically relevant evidence for intra-aortic balloon pump, Impella, TandemHeart and ECMO and their role as pMCS in high-risk percutaneous coronary intervention, transcatheter valvular procedures, ablations and high-risk pulmonary embolism. We found that the right choice of periprocedural pMCS could provide a solution for the hemodynamic challenges during these procedures. However, to enhance the understanding of the safety and effectiveness of pMCS devices in an often high-risk population, more randomized research is needed.

Magnetocardiography at rest predicts cardiac death in patients with acute chest pain

Introduction

Sudden cardiac arrest is a major cause of morbidity and mortality worldwide and remains a major public health problem for which better non-invasive prediction tools are needed. Primary preventive therapies, such as implantable cardioverter defibrillators, are not personalized and not predictive. Most of these devices do not deliver life-saving therapy during their lifetime. The individual relationship between fatal arrhythmias and cardiac function abnormalities in predicting cardiac death risk has rarely been explored.

Methods

We retrospectively analyzed the measurements at rest for 191 patients with acute chest pain (ACP) magnetocardiographically. Our recently introduced analyses are able to detect inhomogeneities of the depolarization and repolarization. Moreover, electrically silent phenomena-intracellular ionic currents as well as vortex currents-can be measured and quantified. All included ACP patients were recruited in 2009 at Yonsei University Hospital and were followed up until 2022.

Results

During half of the follow-up period (6.5 years), 11 patients died. Out of all the included nine clinical, eight magnetocardiographical, and nine newly introduced magnetoionographical parameters we tested in this study, three parameters revealed themselves to be outstanding at predicting death: heart rate-corrected QT (QTc) prolongation, depression of repolarization current IKr + IKs, and serum creatinine (all significant in Cox regression, p < 0.05). They clearly predicted cardiac death over the 6.5 years duration (sensitivity 90.9%, specificity 85.6%, negative predictive accuracy 99.4%). Cardiac death risk was more than ninefold higher in patients with low repolarization reserve and QTc prolongation in comparison with the remaining patients with ACP (p < 0.001). The non-parametric Kaplan-Meier statistics estimated significantly lower survival functions from their lifetime data (p < 0.001).

Discussion

To the best of our knowledge, these are the first data linking magnetocardiographical and magnetoionographical parameters and subsequent significant fatal events in people, suggesting structural and functional components to clinical life-threatening ventricular arrhythmogenesis. The findings support investigation of new prevention strategies and herald those new non-invasive techniques as complementary risk stratification tools.

Technical development and feasibility of a reusable vest to integrate cardiovascular magnetic resonance with electrocardiographic imaging

BACKGROUND

Electrocardiographic imaging (ECGI) generates electrophysiological (EP) biomarkers while cardiovascular magnetic resonance (CMR) imaging provides data about myocardial structure, function and tissue substrate. Combining this information in one examination is desirable but requires an affordable, reusable, and high-throughput solution. We therefore developed the CMR-ECGI vest and carried out this technical development study to assess its feasibility and repeatability in vivo.

METHODS

CMR was prospectively performed at 3T on participants after collecting surface potentials using the locally designed and fabricated 256-lead ECGI vest. Epicardial maps were reconstructed to generate local EP parameters such as activation time (AT), repolarization time (RT) and activation recovery intervals (ARI). 20 intra- and inter-observer and 8 scan re-scan repeatability tests.

RESULTS

77 participants were recruited: 27 young healthy volunteers (HV, 38.9 ± 8.5 years, 35% male) and 50 older persons (77.0 ± 0.1 years, 52% male). CMR-ECGI was achieved in all participants using the same reusable, washable vest without complications. Intra- and inter-observer variability was low (correlation coefficients [rs] across unipolar electrograms = 0.99 and 0.98 respectively) and scan re-scan repeatability was high (rs between 0.81 and 0.93). Compared to young HV, older persons had significantly longer RT (296.8 vs 289.3 ms, p = 0.002), ARI (249.8 vs 235.1 ms, p = 0.002) and local gradients of AT, RT and ARI (0.40 vs 0.34 ms/mm, p = 0,01; 0.92 vs 0.77 ms/mm, p = 0.03; and 1.12 vs 0.92 ms/mm, p = 0.01 respectively).

CONCLUSION

Our high-throughput CMR-ECGI solution is feasible and shows good reproducibility in younger and older participants. This new technology is now scalable for high throughput research to provide novel insights into arrhythmogenesis and potentially pave the way for more personalised risk stratification.

CLINICAL TRIAL REGISTRATION

Title: Multimorbidity Life-Course Approach to Myocardial Health-A Cardiac Sub-Study of the MRC National Survey of Health and Development (NSHD) (MyoFit46). National Clinical Trials (NCT) number: NCT05455125. URL: https://clinicaltrials.gov/ct2/show/NCT05455125?term=MyoFit&draw=2&rank=1.

The association of tibial vs. humeral intraosseous vascular access with patient outcomes in adult out-of-hospital cardiac arrests

AIM

Humeral and tibial intraosseous (IO) vascular access can deliver resuscitative medications for out-of-hospital cardiac arrest (OHCA), however the optimal site is unclear. We examined the association between IO tibia vs. humerus as the first-attempted vascular access site with OHCA outcomes.

METHODS

We used prospectively-collected data from the British Columbia Cardiac Arrest registry, including adult OHCAs treated with IO humerus or IO tibia as the first-attempted intra-arrest vascular access. We fit logistic regression models on the full study cohort and a propensity-matched cohort, to estimate the association between IO site and both favorable neurological outcomes (Cerebral Performance Category 1-2) and survival at hospital discharge.

RESULTS

We included 1041 (43%) and 1404 (57%) OHCAs for whom IO humerus and tibia, respectively, were the first-attempted intra-arrest vascular access. Among humerus and tibia cases, 1010 (97%) and 1369 (98%) had first-attempt success, and the median paramedic arrival-to-successful access interval was 6.7 minutes (IQR 4.4-9.4) and 6.1 minutes (IQR 4.1-8.9), respectively. In the propensity-matched cohort (n = 2052), 31 (3.0%) and 44 (4.3%) cases had favourable neurological outcomes in the IO humerus and IO tibia groups, respectively; compared to IO humerus, we did not detect an association between IO tibia with favorable neurological outcomes (OR 1.44; 95% CI 0.90-2.29) or survival to hospital discharge (OR 1.29; 95% CI 0.83-2.01). Results using the full cohort were similar.

CONCLUSIONS

We did not detect an association between the first-attempted intra-arrest IO site (tibia vs. humerus) and clinical outcomes. Clinical trials are warranted to test differences between vascular access strategies.

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.

Statement from the Asia Summit: Current state of arrhythmia care in Asia

On May 27, 2022, the Asia Pacific Heart Rhythm Society and the Heart Rhythm Society convened a meeting of leaders from different professional societies of healthcare providers committed to arrhythmia care from the Asia Pacific region. The overriding goals of the meeting were to discuss clinical and health policy issues that face each country for providing care for patients with electrophysiologic issues, share experiences and best practices, and discuss potential future solutions. Participants were asked to address a series of questions in preparation for the meeting. The format of the meeting was a series of individual country reports presented by the leaders from each of the professional societies followed by open discussion. The recorded presentations from the Asia Summit can be accessed at https://www.heartrhythm365.org/URL/asiasummit-22. Three major themes arose from the discussion. First, the major clinical problems faced by different countries vary. Although atrial fibrillation is common throughout the region, the most important issues also include more general issues such as hypertension, rheumatic heart disease, tobacco abuse, and management of potentially life-threatening problems such as sudden cardiac arrest or profound bradycardia. Second, there is significant variability in the access to advanced arrhythmia care throughout the region due to differences in workforce availability, resources, drug availability, and national health policies. Third, collaboration in the area already occurs between individual countries, but no systematic regional method for working together is present.

Predicting Risk of Cardiac Arrest in Young Asian Americans: Insights from an Artificial Neural Network Analysis of the Nationwide Cohort

We used the Artificial Neural Network (ANN) model to identify predictors of Sudden Cardiac Arrest (SCA) in a national cohort of young Asian patients in the United States. The National Inpatient Sample (2019) was used to identify young Asians (18-44-year-old) who were hospitalized with SCA. The neural network's predicted criteria for SCA were selected. After eliminating missing data, young Asians (n = 65,413) were randomly divided into training (n = 45,094) and testing (n = 19347) groups. Training data (70%) was used to calibrate ANN while testing data (30%) was utilized to assess the algorithm's accuracy. To determine ANN's performance in predicting SCA, we compared the frequency of incorrect prediction between training and testing data and measured the area under the Receiver Operating Curve (AUC). The 2019 young Asian cohort had 327,065 admissions (median age 32 years; 84.2% female), with SCA accounting for 0.21%. The exact rate of error in predictions vs. tests was shown by training data (0.2% vs 0.2%). In descending order, the normalized importance of predictors to accurately predict SCA in young adults included prior history of cardiac arrest, sex, age, diabetes, anxiety disorders, prior coronary artery bypass grafting, hypertension, congenital heart disease, income, peripheral vascular disease, and cancer. The AUC was 0.821, indicating an excellent ANN model for SCA prediction. Our ANN models performed excellently in revealing the order of important predictors of SCA in young Asian American patients. These findings could have a considerable impact on clinical practice to develop risk prediction models to improve the survival outcome in high-risk patients.

Artificial Intelligence and Machine Learning Applications in Sudden Cardiac Arrest Prediction and Management: A Comprehensive Review

PURPOSE OF REVIEW

This literature review aims to provide a comprehensive overview of the recent advances in prediction models and the deployment of AI and ML in the prediction of cardiopulmonary resuscitation (CPR) success. The objectives are to understand the role of AI and ML in healthcare, specifically in medical diagnosis, statistics, and precision medicine, and to explore their applications in predicting and managing sudden cardiac arrest outcomes, especially in the context of prehospital emergency care.

RECENT FINDINGS

The role of AI and ML in healthcare is expanding, with applications evident in medical diagnosis, statistics, and precision medicine. Deep learning is gaining prominence in radiomics and population health for disease risk prediction. There's a significant focus on the integration of AI and ML in prehospital emergency care, particularly in using ML algorithms for predicting outcomes in COVID-19 patients and enhancing the recognition of out-of-hospital cardiac arrest (OHCA). Furthermore, the combination of AI with automated external defibrillators (AEDs) shows potential in better detecting shockable rhythms during cardiac arrest incidents. AI and ML hold immense promise in revolutionizing the prediction and management of sudden cardiac arrest, hinting at improved survival rates and more efficient healthcare interventions in the future. Sudden cardiac arrest (SCA) continues to be a major global cause of death, with survival rates remaining low despite advanced first responder systems. The ongoing challenge is the prediction and prevention of SCA. However, with the rise in the adoption of AI and ML tools in clinical electrophysiology in recent times, there is optimism about addressing these challenges more effectively.

Contribution and therapeutic value of mitophagy in cerebral ischemia-reperfusion injury after cardiac arrest

Cardiopulmonary resuscitation and related life support technologies have improved substantially in recent years; however, mortality and disability rates from cardiac arrest (CA) remain high and are closely associated with the high incidence of cerebral ischemia-reperfusion injury (CIRI), which is explained by a "double-hit" model (i.e., resulting from both ischemia and reperfusion). Mitochondria are important power plants in the cell and participate in various biochemical processes, such as cell differentiation and signaling in eukaryotes. Various mitochondrial processes, including energy metabolism, calcium homeostasis, free radical production, and apoptosis, are involved in several important stages of the progression and development of CIRI. Mitophagy is a key mechanism of the endogenous removal of damaged mitochondria to maintain organelle function and is a critical target for CIRI treatment after CA. Mitophagy also plays an essential role in attenuating ischemia-reperfusion in other organs, particularly during post-cardiac arrest myocardial dysfunction. Regulation of mitophagy may influence necroptosis (a programmed cell death pathway), which is the main endpoint of organ ischemia-reperfusion injury. In this review, we summarize the main signaling pathways related to mitophagy and their associated regulatory proteins. New therapeutic methods and drugs targeting mitophagy in ischemia-reperfusion animal models are also discussed. In-depth studies of the mechanisms underlying the regulation of mitophagy will enhance our understanding of the damage and repair processes in CIRI after CA, thereby contributing to the development of new therapeutic strategies.

Deep learning unmasks the ECG signature of Brugada syndrome

One in 10 cases of sudden cardiac death strikes without warning as the result of an inherited arrhythmic cardiomyopathy, such as Brugada Syndrome (BrS). Normal physiological variations often obscure visible signs of this and related life-threatening channelopathies in conventional electrocardiograms (ECGs). Sodium channel blockers can reveal previously hidden diagnostic ECG features, however, their use carries the risk of life-threatening proarrhythmic side effects. The absence of a nonintrusive test places a grossly underestimated fraction of the population at risk of SCD. Here, we present a machine-learning algorithm that extracts, aligns, and classifies ECG waveforms for the presence of BrS. This protocol, which succeeds without the use of a sodium channel blocker (88.4% accuracy, 0.934 AUC in validation), can aid clinicians in identifying the presence of this potentially life-threatening heart disease.

The Role of miRNA Expression Profile in Sudden Cardiac Death Cases

Sudden cardiac death (SCD) is one of the leading causes of death in the world and for this reason it has attracted the attention of numerous researchers in the field of legal medicine. It is not easy to determine the cause in a SCD case and the available methods used for diagnosis cannot always give an exhaustive answer. In addition, the molecular analysis of genes does not lead to a clear conclusion, but it could be interesting to focus attention on the expression level of miRNAs, a class of non-coding RNA of about 22 nucleotides. The role of miRNAs is to regulate the gene expression through complementary binding to 3'-untraslated regions of miRNAs, leading to the inhibition of translation or to mRNA degradation. In recent years, several studies were performed with the aim of exploring the use of these molecules as biomarkers for SCD cases, and to also distinguish the causes that lead to cardiac death. In this review, we summarize experiments, evidence, and results of different studies on the implication of miRNAs in SCD cases. We discuss the different biological starting materials with their respective advantages and disadvantages, studying miRNA expression on tissue (fresh-frozen tissue and FFPE tissue), circulating cell-free miRNAs in blood of patients affected by cardiac disease at high risk of SCD, and exosomal miRNAs analyzed from serum of people who died from SCD.

Toward advanced diagnosis and management of inherited arrhythmia syndromes: Harnessing the capabilities of artificial intelligence and machine learning

The use of advanced computational technologies, such as artificial intelligence (AI), is now exerting a significant influence on various aspects of life, including health care and science. AI has garnered remarkable public notice with the release of deep learning models that can model anything from artwork to academic papers with minimal human intervention. Machine learning, a method that uses algorithms to extract information from raw data and represent it in a model, and deep learning, a method that uses multiple layers to progressively extract higher-level features from the raw input with minimal human intervention, are increasingly leveraged to tackle problems in the health sector, including utilization for clinical decision support in cardiovascular medicine. Inherited arrhythmia syndromes are a clinical domain where multiple unanswered questions remain despite unprecedented progress over the past 2 decades with the introduction of large panel genetic testing and the first steps in precision medicine. In particular, AI tools can help address gaps in clinical diagnosis by identifying individuals with concealed or transient phenotypes; enhance risk stratification by elevating recognition of underlying risk burden beyond widely recognized risk factors; improve prediction of response to therapy, and further prognostication. In this contemporary review, we provide a summary of the AI models developed to solve challenges in inherited arrhythmia syndromes and also outline gaps that can be filled with the development of intelligent AI models.

Cooling Down Inflammation in the Cardiovascular System via the Nicotinic Acetylcholine Receptor

ABSTRACT

Inflammation is a major player in many cardiovascular diseases including hypertension, atherosclerosis, myocardial infarction, and heart failure. In many individuals, these conditions coexist and mutually exacerbate each other's progression. The pathophysiology of these diseases entails the active involvement of both innate and adaptive immune cells. Immune cells that possess the α7 subunit of the nicotinic acetylcholine receptor on their surface have the potential to be targeted through both pharmacological and electrical stimulation of the cholinergic system. The cholinergic system regulates the inflammatory response to various stressors in different organ systems by systematically suppressing spleen-derived monocytes and chemokines and locally improving immune cell function. Research on the cardiovascular system has demonstrated the potential for atheroma plaque stabilization and regression as favorable outcomes. Smaller infarct size and reduced fibrosis have been associated with improved cardiac function and a decrease in adverse cardiac remodeling. Furthermore, enhanced electrical stability of the myocardium can lead to a reduction in the incidence of ventricular tachyarrhythmia. In addition, improving mitochondrial dysfunction and decreasing oxidative stress can result in less myocardial tissue damage caused by reperfusion injury. Restoring baroreflex activity and reduction in renal damage can promote blood pressure regulation and help counteract hypertension. Thus, the present review highlights the potential of nicotinic acetylcholine receptor activation as a natural approach to alleviate the adverse consequences of inflammation in the cardiovascular system.

The Lancet Commission to reduce the global burden of sudden cardiac death: a call for multidisciplinary action

Despite major advancements in cardiovascular medicine, sudden cardiac death (SCD) continues to be an enormous medical and societal challenge, claiming millions of lives every year. Efforts to prevent SCD are hampered by imperfect risk prediction and inadequate solutions to specifically address arrhythmogenesis. Although resuscitation strategies have witnessed substantial evolution, there is a need to strengthen the organisation of community interventions and emergency medical systems across varied locations and health-care structures. With all the technological and medical advances of the 21st century, the fact that survival from sudden cardiac arrest (SCA) remains lower than 10% in most parts of the world is unacceptable. Recognising this urgent need, the Lancet Commission on SCD was constituted, bringing together 30 international experts in varied disciplines. Consistent progress in tackling SCD will require a completely revamped approach to SCD prevention, with wide-sweeping policy changes that will empower the development of both governmental and community-based programmes to maximise survival from SCA, and to comprehensively attend to survivors and decedents' families after the event. International collaborative efforts that maximally leverage and connect the expertise of various research organisations will need to be prioritised to properly address identified gaps. The Commission places substantial emphasis on the need to develop a multidisciplinary strategy that encompasses all aspects of SCD prevention and treatment. The Commission provides a critical assessment of the current scientific efforts in the field, and puts forth key recommendations to challenge, activate, and intensify efforts by both the scientific and global community with new directions, research, and innovation to reduce the burden of SCD worldwide.

R. Whitman G, Cho SM. A recommended preclinical extracorporeal cardiopulmonary resuscitation model for neurological outcomes: A scoping review

Background

Despite the high prevalence of neurological complications and mortality associated with extracorporeal cardiopulmonary resuscitation (ECPR), neurologically-focused animal models are scarce. Our objective is to review current ECPR models investigating neurological outcomes and identify key elements for a recommended model.

Methods

We searched PubMed and four other engines for animal ECPR studies examining neurological outcomes. Inclusion criteria were: animals experiencing cardiac arrest, ECPR/ECMO interventions, comparisons of short versus long cardiac arrest times, and neurological outcomes.

Results

Among 20 identified ECPR animal studies (n = 442), 13 pigs, 4 dogs, and 3 rats were used. Only 10% (2/20) included both sexes. Significant heterogeneity was observed in experimental protocols. 90% (18/20) employed peripheral VA-ECMO cannulation and 55% (11/20) were survival models (median survival = 168 hours; ECMO duration = 60 minutes). Ventricular fibrillation (18/20, 90%) was the most common method for inducing cardiac arrest with a median duration of 15 minutes (IQR = 6-20). In two studies, cardiac arrests exceeding 15 minutes led to considerable mortality and neurological impairment. Among seven studies utilizing neuromonitoring tools, only four employed multimodal devices to evaluate cerebral blood flow using Transcranial Doppler ultrasound and near-infrared spectroscopy, brain tissue oxygenation, and intracranial pressure. None examined cerebral autoregulation or neurovascular coupling.

Conclusions

The substantial heterogeneity in ECPR preclinical model protocols leads to limited reproducibility and multiple challenges. The recommended model includes large animals with both sexes, standardized pre-operative protocols, a cardiac arrest time between 10-15 minutes, use of multimodal methods to evaluate neurological outcomes, and the ability to survive animals after conducting experiments.