We report a 71-year-old woman with inferior acute myocardial infarction (AMI) due to type A acute aortic dissection. Emergency enhanced computed tomography (CT) did not show obvious aortic dissection. During emergency percutaneous coronary intervention (PCI), intravascular ultrasonography revealed type A aortic dissection. Hemodynamic stability was restored after PCI. 1 month later, CT revealed a sinus of Valsalva aneurysm, which was treated surgically. This case suggests that PCI could be a good initial treatment option for unstable patients with AMI due to type A aortic dissection. This is the first reported case of sinus of Valsalva aneurysm subsequent to aortic dissection.