Sudden cardiac death is a relatively common cause of death in the elderly, with the majority of cases due to structural heart disease. Sudden cardiac death in the young (<35y) is a less frequent occurrence and more commonly suggests an inherited form of heart disease. While the most common cause of sudden cardiac death in the young is a result of hypertrophic cardiomyopathy, a finding that can frequently be detected by autopsy, the occurrence of sudden cardiac death with no identifiable cause present a diagnostic problem and is considered to be a sudden unexplained death (SUD). An estimated 1/3 of sudden death cases in individuals younger than 20 years do not have an identifiable cause at autopsy and arrhythmia should be considered in the differential diagnosis.
Long QT syndrome (LQTS), Brugada syndrome, and Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) are inherited forms of arrhythmia that frequently manifest symptoms before the age of 50, with some cases occurring in infancy. In each of these conditions, a significant proportion of patients present with sudden death as the first symptom. Other symptoms include palpitations, syncope, and dizziness. The diseases included in this post- mortem arrhythmia panel occur in all ethnicities and incidence varies from 1 in 3000 to 1 in 10,000.