How Long Can One Survive Without Surgery When Having Marfan Syndrome?

My brother is a marfan syndrom. He is 43 now and now diagnosed as sever ARgrade IV AR Aneurysmal dialation of arotic root ,ascending aorta (68mm),mild MR ,mild TR ,mild PN, severely dialated left ventricle (75mm) and suggested Bentall s operation . Within how many days he should be operated? What is life span if not operated? what is the success rate if operated? Pl. comment