Anomalous origin of left main coronary artery from the right sinus of Valsalva

Background Anomalous coronary arteries are rare congenital variations with cases ranging from asymptomatic to life-threatening. Given the wide variability of coronary anomalies, it is challenging to predict their clinical consequences. Here, we present the 'malignant' variant - interarterial course of the left coronary artery between the aorta and pulmonary trunk - given the highest risk of sudden cardiac death among the various coronary anomalies. Case presentation Our case presents a 22-year-old male presenting to the emergency department after a syncopal episode that occurred while the patient was driving a motor vehicle. Initial Computed Tomography (CT) of the chest performed as part of the trauma work-up revealed a rare case of an anomalous origin of the left main coronary artery (LMCA) originating from a common ostium with the right coronary artery (RCA). The LMCA was found to have a malignant course, as it was positioned between the aorta and pulmonary artery. Given the high risk of sudden cardiac arrest with this congenital variant, the patient underwent coronary artery bypass grafting. Conclusion Anomalous coronary arteries remain the second leading cause of sudden cardiac death in young adult patients. The risk of sudden cardiac death depends on the congenital variant of the anomalous coronary artery as well as the course these vessels take. This case highlights a rare congenital variant featuring both the LMCA and RCA originating from a common ostium, with the LMCA having a malignant course, a variant with the highest risk of sudden cardiac death.