A Stanford type A aortic dissection ruptures usually into the pericardial space or the mediastinal space. We herein report the rare surgical case of a Stanford type A aortic dissection which ruptured into the left atrium. The patient had a previous history of mitral valve replacement. The time and the cause of the aortic dissection was unclear. At operation, adhesions around the proximal aorta and between the aortic root and the left atrial roof were confirmed to be one of the causes for this rare form. A fistula to the cardiac cavity following an aortic dissection may occur in any patient, especially in those with a history of previous cardiac surgery.