Long-term sudden cardiac death (abbreviation: SCAR) focuses on improving the predictability of sudden cardiac death (SCD) in patients diagnosed with coronary artery disease. The aim of the study is to determine the predictive value of measurable biological variables (including genetic factors, cardiac electrical activity, biological markers measured from circulation, and coronary artery anatomy) as well as the patients' psychosocial factors in predicting SCDs.

The purpose of this study is the identification of a subgroup of coronary artery disease patients at sufficiently high risk in whom it may be possible to prevent sudden cardiac arrests and subsequent deaths using implantable cardioverter-defibrillators. The study is intended to establish a clear foundation for future interventional studies targeting high-risk coronary artery disease patients.

The primary endpoint of the study is SCD/sudden cardiac arrest (SCA) or a comparable malignant arrhythmic event (i.e., resuscitation). Secondary endpoints include other major cardiovascular events occurring during the follow-up period (such as cerebrovascular events, myocardial infarctions, revascularizations, and new arrhythmias like atrial fibrillation following procedures or after the patient has been discharged following recruitment) or the occurrence and mortality of other significant life-threatening diseases (such as cancer). Secondary endpoints also include poor success in secondary prevention, which can be assessed through completed medication purchases and the achievement of secondary prevention goals.

This observational, prospective study includes collecting multimodal data from hospitals in Finland (TAUH), Israel (HYMC), Moldova (IMSP) and Romania (UMFCD). Each participating institution has followed a process structured by Tampere Heart Hospital (TAUH) for securing permissions in line with EU and national regulations.

Sudden cardiac arrest (SCA) and sudden cardiac death (SCD) are most commonly caused by malignant ventricular arrhythmias in patients with underlying coronary artery disease (CAD). Current risk stratification strategies, largely based on left ventricular ejection fraction, identify only a minority of patients who will experience SCA/SCD. Traditional cardiovascular risk factors lack sufficient specificity for arrhythmic death and are frequently associated with competing non-arrhythmic mortality. Improved, biologically informed risk prediction tools are therefore needed.

This prospective, multicenter observational study is designed to validate and refine multimodal risk prediction models for SCA/SCD in patients with imaging-confirmed CAD. Recruitment is planned between 2024 and 2026 across centers in Finland, Israel, Romania, and Moldova, with long-term follow-up extending up to 10-15 years. The anticipated total sample size is approximately 1,500-2,000 participants.

Baseline data collection includes comprehensive clinical information, imaging findings, electrocardiographic parameters, circulating biomarkers, lifestyle factors, and genetic samples. Imaging and biosignal data are stored in standardized digital formats to enable advanced analyses. Biological samples are stored for future genomic (including full genome sequencing and RNA expression data) and molecular analyses. All participants receive guideline-directed care; no experimental interventions are introduced.

The primary objective is to evaluate the performance of an AI-based risk assessment framework in identifying CAD patients at elevated risk of SCA/SCD, particularly during the first year after coronary angiography, and to assess its long-term predictive performance. Additional objectives include validation of previously reported arrhythmic risk markers, development of updated multivariable risk models, and evaluation of postoperative atrial fibrillation risk in patients undergoing coronary artery bypass grafting.

Primary endpoints include incident SCA, SCD, or equivalent malignant ventricular arrhythmic events. Secondary endpoints include major cardiovascular events, device therapies, heart failure hospitalization, new-onset atrial fibrillation, and all-cause mortality. Endpoints are adjudicated locally by blinded physician panels based on registry data and clinical documentation, with competing causes of death taken into account in the analyses.

Data analysis focuses on evaluating associations between predefined exposure variables and clinical outcomes, validating predictive models across participating centers, and applying federated analytical approaches when appropriate to enable cross-population validation without sharing individual-level data.

The study is observational and does not alter patient management. All procedures comply with applicable regulatory and ethical requirements. Genetic and exploratory biomarker analyses are conducted for research purposes only and are not returned to participants.

Inclusion Criteria:

• Age ≥ 18 years old

• Ability to give informed consent

• Imaging confirmed diagnosis within the past 12 months (coronary artery angiography or contrast enhanced coronary computed tomography)

  •>50% of stenosis and/or fractional flow-reserve <0.8 verified by selective coronary angiography or by contrast enhanced coronary computed tomography (CT) or type I MI with atherosclerotic origin (despite stenosis percentage)

• Patients may be recruited during index event visit (out-patient clinic visit, invasive procedure, hospitalization) (or if logistically possible recall patients previously diagnosed within 12 months)

Exclusion Criteria:

• Age > 75 years of age
• Clinically significant previously treated valvular heart disease or requiring operative (surgical or endovascular) treatment within following three months
• Diagnosed severe neurodegenerative disease (ALS, myositis, multiple sclerosis, or Parkinson's disease) or known impaired cognitive function (MMSE <23)
• Known developmental disability impairing legal ability to give written consent
• Serious/active malignancy with possibly reduced life expectancy of <1 year (estimated by a physician)
• Inability to give written consent for some other reason
• Other significant cardiac condition severely linked to the risk of fatal ventricular arrhythmia (for example ARVCD, non-ischemic DCM, HCM or genetic long or short QT syndrome)
• Other cardiac disease with <1 years of life expectancy
• Do-Not-Resuscitate (DNR) order made due to any reason
• Previously done or planned cardiac, renal, or liver transplant
• Participation in another clinical trial where the active treatment

All consecutive patients with coronary artery disease meeting the inclusion criteria during the recruitment period will be invited to participate

The data collected in the SCAR is used primarily for EU funded project CVD LINK. After CVD Link each participating center will decide of the use of the data based on local legislation and data protection regulations.