The Role of Electrophysiology Testing in Survivors of Unexplained Cardiac Arrest

The majority of cases of SCD in older individuals occur secondary to coronary and structural heart disease, while genetic channelopathies and cardiomyopathies are prominent contributors in young adults. Among individuals that suffer aborted cardiac arrests in the absence of overt coronary and structural heart disease, diagnostic algorithms that screen for cardiac channelopathies and more subtle forms of structural heart disease have been established. Despite the extensive investigations currently utilized, a significant proportion of aborted cardiac arrests remain unexplained. Although invasive electrophysiology studies are a cornerstone for diagnosis and management of arrhythmia disorders, they are not invariably included in the workup of cases of unexplained aborted cardiac arrest. This is largely driven by initial studies suggesting that the diagnostic yield in this context is low, however these investigations often used invasive electrophysiology studies indiscriminately in all cases of aborted cardiac arrest. Since these earlier studies, our insight and approach to SCD has evolved and it has become clear that the majority of patients do not require an invasive electrophysiology study for diagnosis. However an invasive electrophysiology study may still have an important role among these individuals when the initial workup is negative. Notably, arrhythmias that require invasive electrophysiology for diagnosis, including bundle branch reentrant ventricular tachycardia and supraventricular tachycardias associated with hemodynamic collapse, have been identified as arrhythmic culprits in this patient population. The goal of the EPS ARREST study is to evaluate the diagnostic yield of a standardized invasive electrophysiology study among survivors of SCD when initial investigations fail to identify an underlying etiology.