Acute DeBakey type I aortic dissection (ATAD) is one of the most lethal surgical emergencies. The conventional operative strategy is hemiarch replacement under cardiopulmonary bypass support to replace the diseased segment of the ascending aorta. However, in patients with dissection involving the whole aortic arch and descending thoracic aorta, the presence of the persistently perfused false lumen can lead to late aneurysm formation and require a second-stage operation, and this reduces long-term survival. In the surgical literature, there is growing evidence that the presence of Distal Anastomosis New Entry (DANE), which is a new intimal defect related to the trauma created by surgical sutures, is associated with persistent perfusion of the false lumen, aortic size growth, and the need of re-operation. The Ascyrus Medical Dissection Stent (AMDS; Artivion, Atlanta, Georgia, USA) is a hybrid prosthesis with a proximal sewing collar and distal nitinol self-expanding un-covered stent system designed to reduce the occurrence of DANE and hopefully depressurize the false lumen and lead to remodeling of the aortic wall. The investigators plan to prospectively recruit consecutive patients with acute ascending thoracic aortic dissection patients (Excluding DeBakey II) and randomized them, after informed consent, into either the conventional hemiarch replacement group (Hemiarch-C) or the hemiarch replacement plus AMDS implantation group (Hemiarch-AMDS). The participating team will collect pre-operative, intra-operative and post-operative clinical and radiological parameters for two groups of patients. Written informed consent, specifically allowing the use of clinical records for this randomized study, will be obtained from every patient prior to data collection. Complete DICOM image files of the CT scans will be evaluated by two independent fully qualified Radiologists. Our primary outcome is the radiological detection of DANE in Hemiarch-C and Hemiarch-AMDS groups within the 12-month follow-up period. This study will be the world's first randomized control trial in ATAD to compare the prevalence of DANE in Hemiarch-C and Hemiarch-AMDS. It could be a guideline-changing study for the treatment of ATAD and its impact on the immediate survival, second-stage treatment, and long-term survival of patients suffering from ATAD.