The present disclosure includes an endoprosthesis comprising a descending stent-graft, an ascending stent-graft, and/or a side-branch stent-graft. In various embodiments, an ascending stent-graft is capable of being coupled to a descending stent-graft, and/or a descending stent-graft can comprise a fenestration capable of being coupled to a side-branch stent-graft. In addition, in various embodiments, a descending and/or ascending stent-graft can comprise a reduced diameter portion that, when implanted within an aortic arch, recedes from a luminal surface of the aortic arch to allow a side-branch stent-graft to be maneuvered within the aortic arch.