The number of sudden cardiac death is up to 540,000 every year in China. Inherited cardiovascular disease is a common cause of sudden cardiac death in young people, and diseases often have the characteristics of family aggregation, so it has a huge psychological and economic burden on family members. Studying the etiology of sudden cardiac death from the molecular level under the model of precision medicine is helpful for screening patients and their relatives so as to further diagnosis, treatment and management, which has important clinical and social significance.

In this study, sudden cardiac death and high risk of sudden cardiac death in patients younger than 40 years of age are recruited prospectively after informed consent was given. The investigator will collect the baseline clinical characteristics of the patients at enrollment, including comprehensive physical examination, laboratory testing of blood and urine, electrocardiography, 24-hour Holter, echocardiography, MRI and other examinations if necessary. The specimens retained include blood or oral swabs for all patients, and myocardium for patients receiving autopsy. Genetic testing will be performed to identify carried disease genes, genetic risk factors and potential therapy targets.

Inclusion Criteria:

• Patients with sudden cardiac death and sudden unexplained death diagnosed according current practice guidelines.
• Patients at high risk for sudden cardiac death. (1) Family history of sudden cardiac death at a young age; （2）Successful resuscitation from cardiac arrest; （3) Implantable cardioverter defibrillator implantation after a comprehensive clinical assessment of high risk of sudden cardiac death.

Exclusion Criteria:

• Patients who refuse to sign the informed consent or decline follow-up.
• Patients with sudden death due to car accidents, electric shocks, drowning, fighting, carbon monoxide poisoning and other external causes.
• Patients with sudden death due to other definite causes, such as cerebrovascular accident, severe kidney disease, respiratory disease, neurological disease, etc.

Sudden cardiac death and high risk of sudden cardiac death in patients younger than 40 years of age from multiple centers in China between March 1, 2023 and March 1, 2025.