The patient was a 67-year-old man who was diagnosed with acute myocardial infarction based upon the general symptoms and electrocardiographic findings. Emergent coronary angiography showed a 99% stenosis of the left main coronary artery (LMCA). After the 4.0 mm stent was implanted, he recovered from cardiogenic shock. An acute, Stanford type A aortic dissection was diagnosed by computerized tomography performed after the angioplasty. Transesophageal echocardiography showed that a retrograde dissection of the aorta was compressing the left main coronary ostium. Successful implantation of the stent at the LMCA contributed to saving the patient s life.