Cardiac Arrest (CA)

Sudden cardiac arrest (SCA) remains one of the major challenges in clinical care. Although improvements in resuscitation quality have increased the likelihood of return of spontaneous circulation (ROSC), most patients still fail to survive to hospital discharge, and neurological injury is the leading determinant of poor outcome. Hypoxic-ischemic encephalopathy caused by global cerebral hypoxia during cardiac arrest is a key contributor to long-term disability, and even survivors often experience substantial functional impairment, placing a significant burden on families and society. Targeted temperature management (TTM) has long been regarded as a cornerstone neuroprotective strategy; however, TTM and TTM2 trials reported no significant neurological difference between lower and higher temperature targets. However, these studies predominantly enrolled patients with relatively mild illness severity, and multiple real-world observational cohorts suggest that, among more severely ill resuscitated patients, lower target temperatures may still confer benefit. Consequently, the optimal temperature strategy in higher-risk subgroups remains uncertain. Seizures are another common manifestation of brain injury after cardiac arrest, occurring in approximately 20-30% of resuscitated patients and contributing to secondary neurological damage. Earlier trials evaluating prophylactic anti-seizure medication (ASM) (thiopental or diazepam/magnesium) did not demonstrate neurological benefit; however, these studies primarily focused on neuroprotection rather than seizure prevention, leaving a substantial evidence gap. Patients with moderate to severe disease severity-those at the highest risk of both cerebral injury and seizure occurrence-have never been specifically studied to determine whether personalized temperature selection or early short-term prophylactic ASM (e.g., valproic acid or levetiracetam) may provide clinical benefit. Accordingly, identifying the most appropriate temperature target for higher-risk patients and determining whether short-term prophylactic antiepileptic therapy can reduce seizure-related injury represent important unresolved questions in post-resuscitation care. The aim of this study is to conduct a prospective, multicenter, randomized clinical trial to evaluate whether, among comatose patients with moderate to severe risk after ROSC, specific TTM temperature strategies combined with early short-term prophylactic ASM can reduce postresuscitation seizure incidence and improve neurological outcomes. By addressing a population underrepresented in prior clinical trials-those at highest risk and most likely to benefit-this study aims to generate clinically meaningful evidence to guide temperature selection and prophylactic ASM after cardiac arrest. Evaluating these interventions in combination may provide a more comprehensive understanding of whether they reduce seizure burden, mitigate brain injury, and improve functional recovery.

The purpose of this study is to pilot two resilience interventions for cardiac arrest survivors and their informal caregivers, Recovering Together after Cardiac Arrest 1 and Recovering Together after Cardiac Arrest 2 . The data the investigators gather in this study will be used to further refine the interventions.

The RECOVER study, titled Cardiac Rehabilitation Cohort at the Medicine Campus Davos for Exploration of Recovery, is a prospective, non-interventional, monocentric cohort study conducted at the Hochgebirgsklinik Davos. The study is sponsored by Medicine Campus Davos AG and the Kühne Foundation, with an estimated start date in July 2025 and planned completion by December 2034, with the possibility of extension. The principal investigator of the study is PD Dr. David Niederseer from Hochgebirgsklinik Davos, who also represents the study. The research team includes co-investigators such as Prof. Dr. Stefan Blankenberg and Prof. Dr. Andreas Ziegler from Cardio-CARE, Medicine Campus Davos, as well as Dr. Jan Vontobel from Hochgebirgsklinik Davos. The study will enroll patients referred to Hochgebirgsklinik Davos for cardiac rehabilitation who provide informed consent. Cardiac rehabilitation is an evidence-based therapy for patients with heart disease, including those who have undergone cardiac procedures or surgeries. The primary objectives are to evaluate baseline patient characteristics, rehabilitation strategies, predictors of recovery, and clinical outcomes during and after rehabilitation. To support this, a detailed database and biobank will be established to allow for comprehensive phenotyping, extensive clinical assessments, and long-term follow-up. RECOVER seeks to gain translational insights into how patient-specific factors - such as genetics, plasma, digital and clinical biomarkers, and comorbidities - influence long-term clinical outcomes. The goal is to identify modifiable risk factors to optimize individualized therapeutic approaches in cardiac rehabilitation.

Traumatic brain injury (TBI) and other conditions that reduce blood flow to the brain - such as cardiac arrest (CA) - are life-threatening medical emergencies. When brain cells are damaged, they release specific proteins into the bloodstream. These proteins, called neurobiomarkers, can be measured in blood samples and may help doctors assess the severity of brain injury, guide treatment, and predict patient outcomes. A major gap in current knowledge is how these neurobiomarkers behave during the very first minutes and hours after injury - the so-called "hyperacute" phase - especially when patients are still being treated by paramedics or have just arrived at the emergency department (ED). It is not yet clear whether biomarker levels rise immediately at the moment of injury or gradually over time, and how quickly they can be reliably detected. The CHARON study investigates the time-dependent kinetics of key neurobiomarkers - including S100B, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), neurofilament light chain (NFL), and Tau proteins- during the hyperacute phase of acute brain injury. In addition to these proteins, microRNAs, polar metabolites, and lipid metabolites are also examined as potential biomarkers. The study enrolls three groups of participants: * Patients with severe traumatic brain injury and/or polytrauma treated in the prehospital setting and admitted to the ED with T1 (highest priority) triage classification. * Patients with CA treated (resuscitated) in the prehospital setting. * Patients with severe traumatic brain injury enrolled at hospital (ED) admission. Serial blood samples are collected at multiple time points, beginning during prehospital care and continuing through the first 24 hours of hospital admission. No experimental treatments are given - all participants receive standard medical care. By analyzing biomarker concentration and kinetics across all three groups and correlating findings with neurological outcome at 30 days, the investigators aim to identify the most clinically effective neurobiomarkers for early diagnosis and prognosis of acute brain injury. The study is a prospective multi-center investigation conducted at emergency departments, intensive care units, and ambulance services across Hungary.

NUROPI is a single-centre, prospective, non-interventional study in the Intensive Care Unit (ICU) of Erasme Hospital (Hôpital Universitaire de Bruxelles, Brussels, Belgium). Some critically ill patients get worse during the first days of their ICU stay. Identifying them early could allow faster escalation of care. Nucleosomes are fragments of DNA wrapped around proteins called histones. They are released into the blood when cells die or when white blood cells form neutrophil extracellular traps (NETs). High blood levels of nucleosomes may reflect inflammation, clotting activation and organ damage. This study will measure the H3.1 nucleosome in the blood of 1,000 consecutive adult ICU patients. The measurement uses a CE-marked laboratory test (Nu.Q® NETs, chemiluminescence immunoassay on the IDS-i10 analyser). No additional blood sample is taken for the study. H3.1 is measured on the leftover plasma of blood samples already drawn for routine care, at ICU admission, 6 hours, day 1, day 3 and day 7. Patient treatment is not changed. Patients, or their relatives or legal representative, receive an information notice and may refuse participation at any time. The main question is whether H3.1, alone or combined with routine ICU data, can identify patients at high risk of clinical deterioration within 72 hours of ICU admission. Other questions concern the link between H3.1 and mortality, organ dysfunction, and ICU treatments, and how H3.1 levels change during the first week.

This randomized crossover simulation study will compare two hand positions used during chest compressions: interlocked fingers and non-interlocked hands placed one on top of the other. The study will evaluate whether the non-interlocked hand position is non-inferior to the interlocked-finger technique with regard to chest compression depth, and will compare the two techniques in terms of CPR quality, rescuer comfort, fatigue, pain or discomfort, and perceived hand-position stability.

Cardiac arrest (CA) remains one of the leading causes of death worldwide, and its incidence continues to increase. The median survival rate following in-hospital cardiac arrest in France is 19%. In Europe, it ranges from 15% to 34%. Effective management of cardiac arrest is therefore essential to reduce the mortality rate associated with in-hospital cardiac arrest. However, cardiac arrest is a source of stress in conventional care settings. First, it is a life-threatening emergency in which the absence of effective management results in the patient's death. Furthermore, the occurrence of cardiac arrest in conventional hospital wards, particularly in pediatrics, is uncommon. Healthcare professionals are therefore not accustomed to encountering these situations, which may lead to apprehension, stress, and a lack of confidence in their skills when faced with cardiac arrest. In this context, maintaining skills is essential to ensure effective management of cardiac arrest. Providing open-access training in the workplace would make it possible to maintain a high level of proficiency over time while allowing healthcare professionals to remain at their workplace. The expected benefits are improved management of patients experiencing cardiac arrest through regular training and maintenance of the technical skills of paramedical and medical healthcare professionals in cardiopulmonary resuscitation (CPR). This is a retrospective cohort study evaluating the impact of a pre-/post-training intervention on the level of technical skills used by healthcare professionals in the management of cardiac arrest.

Patients admitted with an acute coronary syndrome (ACS) are at increased risk of malignant cardiac arrhythmias (MA), such as sustained ventricular tachycardia and ventricular fibrillation. Therefore, patients with ST-elevation myocardial infarction (STEMI) are continuously monitored for a minimum of 24 hours after onset symptoms. Longer monitoring is advised in patients at intermediate to high risk of cardiac arrhythmias, however this risk stratification is not evidence based. Hospitalization, particularly in STEMI patients, is advised for a minimum of 48-72 hours. AMI care requires a substantial commitment of bed capacity and staff, resulting in high healthcare costs. In patients who have undergone acute PCI (such as STEMI patients or NSTEMI patients with persistent symptoms), monitoring is primarily aimed at early recognition of MA and signs of persistent or recurrent ischaemia after the intervention. In NSTEMI/UAP patients still awaiting invasive treatment, the emphasis lies on detecting increasing ischaemia in the as-yet untreated coronary vessel, as well as identifying arrhythmias that may arise as a result. The true incidence of MA cannot be precisely established due to heterogeneity in the literature, and moreover varies between patients with ST-elevation myocardial infarction, non-ST-elevation myocardial infarction, and unstable angina pectoris, owing to differences in disease process and care pathway. A better understanding of the current incidence and risk of MA in patients with ACS may contribute to optimizing the monitoring of this patient group, thereby enabling more efficient use of hospital beds and healthcare staff. This prospective quality registry therefore aims to establish the current incidence of MA in ACS patients and to identify potential predictors of MA, while also taking into account other acute complications such as asystole and pulseless electrical activity (PEA).

The purpose of this study is to compare the effectiveness of two defibrillator pad placements, one where pads are placed on the front of the chest and back (anterior-posterior \[AP\]) and one where the pads are placed on the front and side of the chest (anterior-lateral \[AL\]), for the treatment of cardiac arrest. Both pad placement locations are recommended for use by the American Heart Association (AHA) and International Liaison Committee on Resuscitation (ILCOR) and are used in standard treatment. The investigators are hoping to find out if one pad position is more effective than the other in the treatment of cardiac arrest.

This study evaluates whether an augmented reality cardiopulmonary resuscitation feedback system (AR-CPR) can support health care providers in delivering high-quality chest compressions during pediatric cardiac arrest. AR-CPR provides real-time visual feedback on chest compression rate, depth, and recoil through a head-mounted augmented reality display. In this randomized, multicenter, international, simulation-based non-inferiority study, health care providers perform chest compressions during an 18-minute simulated pediatric cardiac arrest. Participants are assigned to receive either real-time feedback from AR-CPR or coaching from a trained human CPR coach. The primary objective is to determine whether the percentage of chest compressions meeting guideline targets for both rate and depth with AR-CPR is non-inferior to that achieved with human CPR coaching.

To give chest compressions during cardiopulmonary resuscitation (CPR), mechanical chest compression devices can be used. During synchronous 30:2 CPR, the standard setting on these devices leave an automated 3-second chest compression pause after 30 compressions to facilitate caregivers in providing two ventilations. With this standard setting, research has shown that in less than half of ventilation pauses during CPR, those two ventilations are given. Increasing the ventilation pause duration to 5 seconds instead of 3 seconds is also an option following current guideline recommendations, and aligns with measured ventilation pause duration in manual CPR. Increasing pause duration to 5 seconds could result in an increased ventilation success rate. This multicenter randomized controlled trial will randomize LUCAS® mechanical compression devices to a standard setting of 3- or 5-second compression pauses. The main outcome will be the percentage of ventilation pauses in which two ventilations are successfully given. Secondary outcomes include the restoration of spontaneous circulation (ROSC), and the difference in (neurologically intact) survival. No study has been performed to evaluate this effect yet.

Each year, France's emergency response services-the SAMU (15) and the fire department (18)-handle 31 million and 19 million calls, respectively. The effectiveness of this system depends on the call centers' ability to obtain location information, prioritize responses, assess the severity of each call, and dispatch appropriate emergency resources. Cardiac arrest (CA) affects 40,000 people in France each year who call on this service. The survival rate decreases by 7 to 10% for every minute that elapses between cardiac arrest and the start of cardiopulmonary resuscitation (CPR). Early CPR performed by bystanders is associated with a survival rate 2-3 times higher than CPR initiated only after emergency responders arrive on the scene. CPR assisted by SAMU-Centre 15 dispatchers (T-CPR) is a way to provide CPR to patients before emergency responders arrive on the scene and is recommended as early as possible to improve survival. According to the American Heart Association (AHA) guidelines, the timing of the initiation of the chain of survival is considered high quality if T-CPR is initiated within 90 seconds. Studies show that recognizing a cardiac arrest (CA) over the phone is often difficult for several reasons, including communication challenges, the caller's stress, and the presence of abnormal breathing. Emergency medical dispatchers (EMDs) receive very little training on communication strategies, particularly those needed to optimally manage stressed and sometimes difficult callers. Interventions to improve communication have proven effective among healthcare professionals. These methods included face-to-face training, blended learning programs, simulation-based teamwork exercises, and communication techniques adapted from aviation. Standardized scripting systems have been shown to improve the speed of decision-making and the dispatch of emergency response teams. These scripts depend on the quality of the information provided by the caller and the caller's ability to communicate effectively with the EMD. The objective of this study will be to evaluate the effect of a communication training program for Centre-15 emergency medical dispatchers on calls for cardiac arrest.

The goal of this platform clinical trial is to evaluate whether specific post-cardiac arrest care strategies can improve neurological recovery and survival in adult patients who remain comatose after return of spontaneous circulation (ROSC) following cardiac arrest and require intensive care management. This multicenter cluster-randomized crossover platform trial (BPT-PCAS) evaluates post-cardiac arrest care strategies within a shared master protocol structure. Participating hospitals are randomized at the institutional level to predefined treatment strategies for fixed study periods and subsequently cross over to alternative strategies according to a predefined allocation schedule. The platform is designed to accommodate multiple independent intervention domains, each evaluating a different post-cardiac arrest care strategy under shared eligibility criteria, infrastructure, data management systems, and follow-up procedures. Participants may be enrolled in one or more active intervention domains according to platform availability and eligibility. Participants will receive the post-cardiac arrest care strategy assigned to their participating hospital during the study period while otherwise undergoing standard intensive care management according to local practice and study protocols. Participants will be followed for neurological outcomes including modified Rankin Scale (mRS), mortality, and safety outcomes at hospital discharge, 30 days, and 90 days after hospital admission.

The purpose of this study is to assess the prognostic value of absolute value and kinetic of neurofilament light chain (NFL) collected at different time points (at admission, 12h, 24h, 48h, 72h, 96h, and day 7 after ICU admission) in predicting poor and good neurological outcome in comatose patients after cardiac arrest.

The goal of this controlled single centre RCT is to compare frequency rates concerning return of spontaneous circulation (ROSC) in prehospital cardiac arrest. Two different algorithms (control-and interventiongroup) of advanced cardiac life support will be used to treat patients. In patients over 18 years suffering from cardiac arrest. The main question aims to answer if the frequency of ROSC differs between the groups receiving either the new Advanced Life Support (ALS) algorithm, or standard treatment. Researchers will compare the new algorithm to the standard care algorithm to see if there is a difference . Participants will be randomized to treatment on scene. The controlgroup will receive ALS standard treatment as performed in local protocols. The intervention group will receive a modified treatment including: * thorax compression via mechanical device (LUCAS 3) * head up Cardiopulmonary Resuscitation (cpr) * use of an impendance threshold device (ITD) module * arterial line placement * continuous epinephrin infusion via infusion pump * double sequence defibrillation

This randomized clinical trial will determine if adult participants who are in the emergency department after being resuscitated from a cardiac arrest outside of the hospital benefit from care delivered at specialized centers. The main question that it will answer is whether transferring participants to a hospital with a specialized cardiac arrest service improves recovery of function after 90 days. Participants will receive all usual medical care, but some participants will be offered transfer to a regional cardiac arrest center and others will be offered care at the closest appropriate hospital. Investigators will interview participants after 90 days to assess their recovery.

The purpose of this study is to find out if a Doppler ultrasound patch placed on the neck can accurately and quickly detect when a cardiac arrest patient's heart starts beating again (return of spontaneous circulation, or ROSC) during resuscitation in the emergency department. The study compares the ultrasound readings to data from an arterial line, which is considered the most reliable way to check for a pulse. The main question the study is trying to answer is whether using Doppler ultrasound is better than the traditional method of feeling for a pulse, which can be unreliable, especially in stressful situations. Secondarily, this study aims to assess blood flow through the carotid artery from chest compressions during resuscitative events to determine overall effectiveness. This research hopes to show that Doppler ultrasound can help medical teams recognize when a patient's heart has restarted more accurately and quickly, leading to better care during cardiac arrest.

This study aims to better understand recovery after coma caused by serious neurologic illness or injury. Patients who are unconscious (in a coma or disorder of consciousness) due to conditions such as stroke, cardiac arrest, traumatic brain injury, seizures, brain infection, or other neurologic emergencies may be enrolled during their hospitalization. The purpose of this observational research study is to learn which medical, neurologic, psychological, and social factors are associated with recovery over time. Researchers will collect information from the medical record during hospitalization, including details about the patient's illness, treatments received, brain imaging, and neurologic examinations. For patients who survive hospitalization, the study team will contact participants or their caregivers after discharge to assess recovery at scheduled time points using questionnaires and structured interviews about physical function, quality of life, emotional well-being, and daily activities. This study does not assign participants to any experimental treatment. Participation will not change the medical care patients receive. Information learned from this study may help improve future care for patients with coma and disorders of consciousness.

Improving Telephone Triage in Emergency Calls with AI The Coordinating Centre for Urgencies and Emergencies in Andalusia (CCUE) handles thousands of calls every day. Each call needs to be assessed based on the information given over the phone to determine how serious the case is. The reasons for calling range from minor health issues to life-threatening emergencies like cardiac arrest (CPA). This project focuses on improving telephone triage for four key emergency situations that often indicate severe or life-threatening conditions: Unconsciousness / Cardiac arrest Difficulty breathing Chest pain (non-traumatic, possible heart-related issues) Stroke symptoms Our goal is to make telephone triage more accurate and efficient by using advanced Artificial Intelligence (AI) techniques, including Machine Learning (ML) and Natural Language Processing (NLP). These tools will help CCUE operators make better and faster decisions, ensuring that patients receive the right care as quickly as possible. How it will be done: The investigators will analyze anonymized historical call data from the emergency coordination system (CCR) and digital clinical records (HCDM). This includes: Structured data: Predefined fields, such as answers to standard triage questions. Unstructured data: Free-text notes and other information recorded during the call. A hybrid AI approach will be used, combining: Traditional AI methods (supervised learning and deep learning) to classify cases. Generative AI techniques (advanced language models) to extract useful insights from free-text data. Building the Best Prediction Model To find the most effective AI model, we will test different machine learning techniques, including: Decision Trees Random Forests Support Vector Machines (SVM) XGBoost Ensemble methods Neural Networks We will also analyze which questions and variables are the most important in predicting the severity of a case. Based on this, we will suggest improvements to the current triage questions to enhance accuracy. Measuring Success We will evaluate the AI model using key performance metrics, including: Accuracy (overall correctness) Sensitivity (ability to detect real emergencies) Specificity (ability to avoid false alarms) False Positive \& False Negative Rates (how often the system makes mistakes) Likelihood Ratios (how well the system distinguishes between urgent and non-urgent cases) F1-Score \& ROC Curve (overall performance indicators) Why This Matters This project will assess how effective the current telephone triage system is and develop a new AI-powered model to improve it. The goal is to help emergency operators quickly identify the most serious cases, reducing response times and improving patient outcomes. In the future, the investigators aim to integrate this improved AI model into the CCUE system to enhance emergency response across Andalusia.

The goal of this platform trial is to determine the efficacy, safety and cost-effectiveness of various interventions in patients with acute cardiorespiratory failure requiring extracorporeal membrane oxygenation (ECMO) The main question the platform trial aims to address is to determine the effect of a range of interventions on survival, organ support and resource utilisation to day 28 for hospitalised patients receiving ECMO. Researchers will compare various interventions within multiple platform trial domains to see if the interventions have effects on survival, organ support and resource utilisation for the patient cohort. Participants will be enrolled in accordance with the platform trial's domain structure to answer the research questions.

Out-of-hospital cardiac arrest (OHCA) is a life-threatening emergency and one of the leading causes of death worldwide. Survival depends critically on how quickly help arrives and whether cardiopulmonary resuscitation (CPR) and defibrillation are started early. In recent years, many regions in Europe and Italy, including Emilia-Romagna, have introduced systems that alert nearby volunteers, called First Responders (FRs), through smartphone applications (such as DAE RespondER). These individuals can reach the patient before emergency medical services (EMS) and begin life-saving actions. The FIRSST-RER study aims to evaluate whether the intervention of First Responders improves survival in patients with out-of-hospital cardiac arrest in Emilia-Romagna. This is a multicentre observational study involving approximately 5,000 adult patients who experienced cardiac arrest between 2018 and 2025 and were treated by the regional emergency system. The study compares two groups of patients: those who received help from at least one First Responder activated via the app those who did not receive First Responder intervention The main objective is to determine whether First Responders increase survival at 30 days after cardiac arrest. Additional objectives include evaluating: survival at 6 months and 1 year neurological outcomes (brain function recovery) Data for this study are collected from existing healthcare and emergency system databases, including EMS dispatch records, national health data systems, and the DAE RespondER platform. For patients who survive, follow-up information may be collected through medical records or telephone contact. Importantly, this study does not involve any experimental treatments or changes in patient care. It is based entirely on data already collected during routine emergency care, and therefore does not pose additional risks to patients. All data are handled securely and in compliance with privacy regulations. Personal identifiers are replaced with coded information (pseudonymisation), and only authorised researchers can access the data. Patients who are alive may be contacted to provide consent and additional follow-up information; participation is voluntary, and consent can be withdrawn at any time. The results of this study will provide important evidence on the effectiveness of citizen responder systems and may help guide future improvements in emergency response organisation, public health strategies, and training programmes. Ultimately, the goal is to increase survival and improve outcomes for people experiencing cardiac arrest in the community.

The aim of the study is to investigate whether occluding the abdominal aorta with an external device could be a potential therapeutic option in cases of non-traumatic cardiac arrest occurring outside of a hospital. In cardiac arrest, the heart suddenly stops beating, causing the circulation of blood to collapse. In this situation, vital organs-especially the brain and the heart itself-are no longer adequately supplied with oxygen. Without immediate treatment, severe damage or death occurs within minutes. The study therefore examines a specific intervention: the temporary occlusion of the abdominal aorta, which carries blood to the lower regions of the body. If this artery is blocked for a short period, the available blood can be redirected more effectively to the upper parts of the body. In theory, this could improve the oxygen supply to these organs and increase the likelihood that the heart will resume beating or that neurological damage can be reduced.

The aim of this study is to assess long-term stress in patients after an out-of-hospital cardiac arrest. To do this, we will measure levels of the stress hormone cortisol in hair samples. Cortisol is produced in larger amounts during periods of ongoing stress and builds up in the hair as it grows. Because hair grows about 1 cm per month, a 3 cm hair sample can show your average stress level over the past three months. The results will be compared with anonymized information from your medical records and the care you received before and during your hospital stay.

\<Study Design\> This study is a cluster-randomized, stratified, non-inferiority trial designed to evaluate the feasibility, efficacy, and educational effectiveness of HEROS 4.0, a mixed-reality (MR)-based cardiopulmonary resuscitation (CPR) training system, compared with conventional instructor-led CPR training. \<Objective \& Hypothesis\> The primary objective is to determine whether MR-based HEROS 4.0 CPR training is non-inferior to standard video- and instructor-based CPR training in improving CPR performance quality. The central hypothesis is that participants trained using HEROS 4.0 will achieve comparable CPR quality to those trained using traditional methods, while benefiting from enhanced immersion, scalability, and accessibility. \<Participants\> A total of 120 adults aged 18-50 years who have not received CPR training within the previous 12 months will be recruited. Participants will be assigned to one of two clusters and randomized in a 1:1 ratio to either the HEROS 4.0 MR training group or the conventional CPR training group. \<Intervention \& Control\> Participants will undergo CPR training according to their assigned group: Intervention group (HEROS 4.0): Participants will receive a two-stage CPR training program consisting of pre-training and on-site MR-based training. As pre-training, participants will be instructed to watch a 40-minute instructional video (conventional CPR training group video) at home prior to their visit. After completing the pre-training, participants will undergo 20 minutes of MR-based CPR training using the HEROS 4.0 system in a dedicated CPR training booth. Control group (Conventional CPR training): Participants will receive 60 minutes of standard CPR education delivered through instructional videos and in-person instructor guidance, reflecting current community CPR training practice. \<Outcomes\> Immediately after training, all participants will undergo a standardized cardiac arrest simulation using a CPR quality-measurement manikin. This simulation will assess objective CPR performance metrics as well as subjective outcomes through questionnaires. To evaluate knowledge retention and skill durability, all assessments will be repeated 6 months after training using the same simulation scenario and outcome measures. The primary outcome is chest compression fraction measured during the standardized simulated cardiac arrest scenario. Secondary outcomes include quantitative measures of CPR quality and participant-reported outcomes based on survey.

The aims are to define the exact prevalence of hereditary heart diseases in out-of-hospital cardiac arrest (OHCA) patients taking also into account gender, patient and OHCA characteristics, provincial settings and environmental pollution; to stratify the individualized arrhythmic risk of proband's family members to prevent further sudden cardiac deaths; to refine the classification of the variants of uncertain significance (VUS) on genes which can have the capability to drive to molecular alterations leading to arrhythmogenic hereditary heart diseases. A blood sample will be obtained during resuscitation from all the patients aged ≤50 years suffering an OHCA in Lombardy Region and then analysed for genetic variants possibly causative of cardiac diseases. Genetic data will be merged with patient, OHCA and post-resuscitation data thanks to the connection with LombardiaCARe, whilst pollution data will be retrieved from ARPA Lombardia for free. A genetic counselling and clinical-instrumental evaluation of the proband's first-degree family members will be performed if a pathogenic/likely pathogenic variant or a VUS will be disclosed during the genetic analysis.