Sudden Cardiac Arrest on the Treadmill: Anomalous Left Main Mimicking Spontaneous Coronary Artery Dissection.

BACKGROUND: A 28-year-old healthy woman collapsed while running on a treadmill, with no known past medical history or conditions. CASE SUMMARY: Initial angiography suggested left main spontaneous coronary artery dissection (SCAD), but coronary computed tomography angiography (CCTA) revealed an anomalous left main coronary artery arising from the right sinus with an intramural interarterial course. Surgical correction was performed. DISCUSSION: This case demonstrates the diagnostic challenges in a young patient presenting with sudden cardiac arrest during exertion, initially presumed to be SCAD; further evaluation with CCTA revealed no evidence of SCAD. The imaging uncovered an anomalous origin of the left main coronary artery from the right coronary sinus with an interarterial and intramural course, which is a high-risk anomaly associated with sudden cardiac death at a young age. TAKE-HOME MESSAGES: Anomalous courses of the left main coronary artery are rare and associated with sudden cardiac death, particularly in young individuals. CCTA is the gold standard for diagnosis, with surgical intervention being the definitive treatment.