ABSTRACT
A 67-year-old man with dyspnea at rest was diagnosed with acute heart failure and admitted to our hospital. Echocardiogram showed severe AR, and CT implied an ascending aortic aneurysm and abnormal space in the aortic root. The patient underwent emergent surgery for suspected acute aortic dissection. Intraoperative findings showed the dehiscence of commissure of the aortic valve, and more, the abnormal space in the aortic root was not due to acute aortic dissection but an aortic subannular left ventricular aneurysm. The aneurysm was sutured and closed, and after that, aortic valve replacement and ascending aortic replacement were performed. Although subannular left ventricular aneurysm is a rare disease, it is important to carry out the preoperative evaluation considering the existence of such diseases.