Etiology of sudden cardiac arrest: Literature review and proposal of an intensive care unit study protocol.

Sudden cardiac arrest (SCA) affects individuals across all age groups and is defined as the sudden cessation of normal cardiac activity, leading to hemodynamic collapse. Determining the etiology of SCA is challenging due to its wide range of cardiac and noncardiac causes. Structural heart disease, mainly coronary artery disease, is predominant in older adults, while cardiomyopathies and primary electrical diseases are more common in younger individuals. Noncardiac causes, such as intracranial hemorrhage and pulmonary embolism, account for 15-25% of cases. This review examines the epidemiology, etiology, and investigation of SCA and proposes a diagnostic approach for SCA patients admitted to the emergency department and intensive care unit. The study protocol is divided into four main stages: (1) initial evaluation, identification of reversible causes, and exclusion of ischemic heart disease and extracardiac disease; (2) assessment of nonischemic cardiac causes; (3) neuroprognostication; and (4) clinical autopsy and/or genetic testing, if appropriate. We emphasize the importance of a multidisciplinary approach, involving an intensivist, cardiologist, geneticist, and pathologist, as well as early genetic testing to identify potential heritable diseases and facilitate early referral of patient relatives. By providing this structured diagnostic algorithm, we aim to improve the management and outcomes of SCA patients.