In the past 20 years, cardiovascular mortality has decreased in high-income countries, in response to the adoption of preventive measures to reduce the burden of coronary artery disease (CAD) and heart failure (HF). Approximately 1 in every 4 deaths is a direct consequence of suden cardiac arrest (SCA), which is defined as sudden cardiac death (SCD). To prevent SCD and decrease the incidence further, risk stratification is crucial for identifying persons at increased risk. Primary prevention of SCD focuses on individuals who are at risk of SCD but have not yet experienced an aborted cardiac arrest or life-threatening arrhythmias. However, accurate risk stratification remains challenging, because approximately 50% of cardiac arrests occur in individuals without a known heart disease and without detectable markers. Additional research is necessary to determine which further tests are effective in these patients, looking at the significance of alterations in cardiac function, signs of electrical instability identified by electrocardiogram abnormalities or by autonomic tests, and the progressive impact of genetic screening. Despite its insufficient accuracy, the only indicator that has consistently shown an association with increased risk of SCD is left ventricular ejection fraction (LVEF). Correct identification of future SCD victims is especially important as there is an effective treatment, namely defibrillation via an external or internal defibrillator. Implantable cardioverter-defibrillators (ICD) are the most widely used devices, while wearable defibrillators require additional research. The most important aspect of the successful prevention of SCD is effective management of underlying diseases and co-morbidities. Approximately 40% of the observed reduction in SCD is the direct consequence of a reduction of CAD and other cardiac conditions.