Sudden cardiac death is an important but uncommon cause of death in the young. The incidence of SCD was 2.7 per 100,000 person-years in Taiwan, which was similar to other Western countries. Its dramatic presentation and cascading effects in the family and community make it a newsworthy event and an important public health issue. The etiology of SCD in the young population includes structural heart disease, hereditary arrhythmia, and coronary artery anomalies. Cardiovascular screening of athletes could decrease risk of SCD in Western countries. In Taiwan, cardiovascular screening for school-age children with EKG-based tools was performed for more than 20 years and could identify high risk patients.
　　Previously, many of SCD in the young population was of unknown causes. Recently, with comprehensive genetic screening, many previous unexplained sudden deaths were known to be hereditary arrhythmia syndrome.Previous report showed the conventional genetic testing including LQTS, Brugada syndrome, CPVT, and ARVC can explain only 10% of patients of unexplained SCD. Therefore, whole exome sequencing may be necessary to define the genetic mechanism and electrophysiology of this malignant form arrhythmia. However, for those of variant with unknown significance, functional assay (with or without induced pleuripotent stem cell functional study) may be necessary to define the underlying electrophysiology mechanism.