Abstract
Acute coronary syndrome in the young population is infrequently seen and has a different etiology from that in the elderly population. Giant coronary artery aneurysms are rare and usually asymptomatic, but they can cause acute clinical symptoms such as chest pain or chest tightness. We herein describe a young woman with a history of mitral valve prolapse who developed sudden-onset chest pain. She had mild elevations of her creatine kinase and cardiac troponin levels; however, no ST segment alteration was found on an electrocardiogram, and no abnormal regional wall movement was noted on echocardiography. Cardiac magnetic resonance imaging with late gadolinium enhancement revealed a "mass" at the right coronary artery and linear subendocardial enhancement at the posterior wall. Coronary angiography later confirmed a giant coronary aneurysm with a substantial thrombus. The combined presence of the coronary artery aneurysm and mitral valve prolapse in this patient was likely a sequela of Kawasaki disease.