Aortic dissection etiology involve many factors that are difficult to identify clearly. We report a 47-year-old man who underwent a Bentall operation with reattachment of bypass grafts for a dissecting aneurysm (DeBakey type II) 4 years after combined triple coronary artery bypass grafting and mitral valve replacement. This case appeared to be associated with factors leading to dissecting aneurysm although it remains unclear which was more influential congenital bicuspid aortic valve or proximal anastomosis of venous grafts or both. This case suggests the need to consider appropriate timing in surgical intervention for cases of congenital bicuspid aortic valves and the selection of additional aortic valve replacement in initial surgery.