Sudden cardiac death in children and young adults without structural heart disease: a comprehensive review

Sudden cardiac death (SCD) is a rare clinical encounter in pediatrics, but its social impact is immense because of its unpredicted and catastrophic nature in previously healthy individuals. Unlike in adults where the primary cause of SCD is related to ischemic heart disease, the etiology is diverse in young SCD victims. Although certain structural heart diseases may be identified during autopsy in some SCD victims, autopsy-negative SCD is more common in pediatrics, which warrants the diagnosis of sudden arrhythmic death syndrome (SADS) based upon the assumption that the usual heart rhythm is abruptly replaced by lethal ventricular arrhythmia. Despite current advances in molecular genetics, the causes of more than half of SADS cases remain unanswered even after postmortem genetic testing. Moreover, the majority of these deaths occur at rest or during sleep even in the young. Recently, sudden unexpected death in epilepsy (SUDEP) has emerged as another etiology of SCD in children and adults, suggesting critical involvement of the central nervous system (CNS) in SCD. Primary cardiac disorders may not be solely responsible for SCD; abnormal CNS function may also contribute to the unexpected lethal event. In this review article, we provide an overview of the complex pathogenesis of SADS and its diverse clinical presentation in the young and postulate that SADS is, in part, induced by unfortunate miscommunication between the heart and CNS via the autonomic nervous system.