Pediatric out-of-hospital cardiac arrest caused by left coronary-artery agenesis with primary shockable rhythm.

Background: To illustrate a rare cause of out-of-hospital cardiac arrest in children, its differential diagnoses, emergency and subsequent treatment at various steps in the rescue chain, and potential outcomes.

Case Presentation: A 4-year-old boy with unknown agenesis of the left coronary ostium sustained out-of-hospital cardiac arrest. Bystander cardio-pulmonary resuscitation was initiated and defibrillation was performed via an automated external defibrillator (AED) shortly after paramedics arrived at the scene, restoring sinus rhythm and spontaneous circulation.