We present a 57-year-old woman with severe aortic stenosis. She was diagnosed with acute myocardial infarction by electrocardiography and the detection of elevated creatine phosphokinase in another hospital. Soon after transfer to our hospital, this patient developed cardiac arrest. Percutaneous cardiopulmonary support (PCPS) was established, and subsequently performed coronary angiography revealed normal coronary arteries. However echocardiography revealed severe aortic stenosis. Emergency aortic valve replacement (AVR) was performed, and the patient was discharged from hospital 30 days after surgery in good health. Prompt establishment of PCPS maintained her systemic circulation, and allowed us to conduct investigations for diagnosis. In patients with critical aortic stenosis, emergency AVR should be performed as early as possible following diagnosis.