The ascending aorta conducts blood from the heart to the rest of the body. The ascending aorta can become enlarged, and the risk of tearing and rupturing becomes higher with larger aorta. When the ascending aorta tears or ruptures, the risk dying is high even if surgery is done as soon as possible. Traditionally, when the ascending aorta gets above 5.5 cm, surgery is recommended to replace the aorta. However, this threshold is based relatively weak evidence, and sometimes patients with smaller aorta can tear or rupture. On the other hand, surgery carries its own risk as well. Since there are risk of waiting or doing surgery, there is currently no great support for either approach for patients with a smaller aorta. In the TITAN SvS trial, patients with an ascending aorta between 5.0 to 5.5 cm is assigned by chance to the early surgery group, in which they will undergo replacement of aorta, or the surveillance group, in which they will be closely monitored. The chance of dying or suffer tearing or rupture of aorta between the two groups will be compared. The result of the trial will guide future practice for patients with enlarged ascending aorta. This is a prospective, multi-centre randomized control trial that compares the all-cause mortality, aneurysm-related aortic events, rate of stroke, and quality of life for those patients undergoing early elective ascending aortic surgery to those patients undergoing surveillance. Patients referred for an ascending aortic aneurysm that meets the inclusion criteria will be randomized to the early elective surgery group or the surveillance group. Recruitment will end when the desired sample size is reached, and the patients will be followed for a minimum 2-year period. The primary objective of the trial is to compare the composite outcome of the all-cause mortality and incidence of acute aortic events between surveillance and elective ascending aortic surgery for patients with degenerative or bicuspid valve-related ascending aortic aneurysm after 2 years of follow up. The hypothesis is that the early surgery group will have a significantly lower all-cause mortality and incidence of acute aortic events at 2 years of follow up compare to the surveillance group. The result of this trial will provide evidence based guidance in the appropriate management of ascending aortic aneurysm based on the size criteria, and establish a large database for future investigations.