Late Gadolinium Enhancement on Cardiac MRI Suggests a Possible Two-Hit Hypothesis for Suspected Commotio Cordis as the Cause of Pediatric Cardiac Arrest

In the United States, there are approximately 20,000 pediatric cardiac arrests per year. The causes of pediatric cardiac arrest include both cardiac and noncardiac, with noncardiac etiologies predominating in 1- to 18-year-olds. We discuss here a case of a 15-year-old male who presented after an out-of-hospital cardiac arrest, which occurred after a blow to the head and chest while playing with his sibling. The initial working diagnosis of commotio cordis became questioned after an extensive workup revealed a myocardial scar on cardiac MRI, consistent with nonischemic cardiomyopathy. Other etiologies of cardiomyopathy were entertained with genetic testing, which proved positive for a pathogenic variant consistent with a carrier state for HFE gene–related hereditary hemochromatosis. This case study highlights the need to investigate future presumed commotio cordis events for secondary, preexisting conditions that may predispose an otherwise asymptomatic individual to a cardiac arrest (i.e., a possible two-hit mechanism).