Acute coronary syndrome caused by left main coronary artery compression between the aortic root and massive dilation of the left atrium.

Left main compression by pulmonary artery dilation has been reported previously. Percutaneous or surgical interventions are treatment options. We report on a 78-year-old man with exertional chest pain and dyspnea. Coronary angiography revealed significant ostial left main artery stenosis. Intravascular ultrasound showed no atherosclerotic plaque but did reveal a rhythmic external compression between the aortic root and another lucent structure. The patient underwent successful stenting of the lesion. Subsequently, 64-slice multidetector coronary computed tomography found the source of compression to be an enlarged left atrium. The patient remains free of coronary insufficiency after 18 months of follow-up.