Background: The management of penetrating thoracic injuries in moribund or unstable patients is clearly described in contrast to that of stable patients, particularly for those with a cardiac box injury. This anatomic location suggests a potentially lethal cardiac injury and requires urgent therapeutic decision making. The present study aims at determining when surgical exploration is beneficial for stable patients presenting with penetrating cardiac box injuries (PCBIs)., Methods: This was a retrospective study of stable civilian patients with PCBI referred to level I trauma centers in the Marseille area between January 2009 and December 2019. Using post hoc analysis of the management outcomes, patients whose surgery was considered therapeutic (group A) were compared with those whose surgery was considered nontherapeutic and with nonoperated patients (group B)., Results: A total of 155 patients with PCBI were included, with 88% (n = 137) of stab wound injuries. Overall, surgical exploration was performed in 54% (n = 83), considered therapeutic in 71% (n = 59), and performed by video-assisted thoracoscopy surgery in 42% (n = 35) with a conversion rates of 14% (n = 5). Initial extended fast assessment with sonography for trauma revealed the presence of hemopericardium in 29% (n = 29) in group A versus 9.5% (n = 7) in group B, p = 0.010, and was associated with a negative predictive value of 93% regarding the presence of a cardiac injury. Chest tube flow was significantly higher in patients who required surgery, with a median (interquartile range) of 600.00 (350.00-1200.00) mL versus 300.0 (150.00-400.00) mL ( p = 0.001)., Conclusion: Extended fast assessment with sonography for trauma and chest tube flow are the cornerstones of the management of stable PCBI. Video-assisted thoracoscopy represents an interesting approach to check intrathoracic wounds while minimizing surgical morbidity., Level of Evidence: Therapeutic/Care Management; Level IV., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)