Commotio cordis is the second leading cause of cardiac death in young athletes. This rare sudden-death mechanism most commonly affects young children playing baseball. It is caused by impacts to the chest during the repolarization phase of the cardiac cycle, which causes the heart to go into ventricular fibrillation, often leading to death. This study adopted the detailed and validated CHARM-10 child finite element model to replicate commotio cordis instances by simulating baseball impacts to the chest. New commotio cordis injury metrics were developed to create a more accurate prediction for chest protector effectiveness. The conventionally used injury metrics for chest protectors did not correlate strongly with left ventricle strain and pressure. This study also identified potentially vulnerable impact locations slightly lateral and above the heart that may be ignored by current commotio cordis safety regulations and commercially available baseball chest protectors.