Sudden cardiac arrest and sudden cardiac death in apparently healthy young adults (aged 18-40 years) are catastrophic life events that have substantial negative effects on patients and their family members. In the US, recent data estimate between 350 000 and 450 000 annual total adult out-of-hospital cardiac arrests, approximately 90% of which are fatal. ➡️ This JAMA Review summarizes the epidemiology and pathophysiology of out-of-hospital cardiac arrest and sudden cardiac death: ja.ma/4gVbKyn