Sudden cardiac death (SCD) is caused by lethal arrhythmias such as ventricular fibrillation and ventricular tachycardia. Ischemic heart diseases (IHD), i.e. acute coronary syndrome and vasospastic angina are a leading cause of SCD, for which emergency medical care system including automated external defibrillator is considerablly developed in Japan. Cardiac myopathies (CM) such as hypertrophic CM (HCM), dilated CM (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC) are a 2nd leading cause of SCD, and inherited arrhythmias such as congenital long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, and early repolarization syndrome account for approximately 10% of SCD in Japan. SCD in IHD generally occurs in elderly population, but that in HCM, ARVC or inherited arrhythmias often develops in young to middle age, therefore, it is of particular importance in health policy to elucidate their pathogenesis leading to the prediction and prevention of SCD. Recent genetic studies have established a link between a number of CM or inherited arrhythmias and mutations in genes encoding for cytoskeletal and desmosomal proteins, or cardiac ion channels. In this symposium, expert physicians and researchers are welcome to present their own experience or research products and provide a comprehensive discussion for the elucidation of pathogenesis, prediction, risk stratification, prevention of SCD in a variety of underlying heart disease for SCD.