A stent-graft includes a graft material having a main body, a first leg, a second leg, and a transition region where the first leg and the second leg meet the main body. A main body transition stent is coupled to the main body. A transition stent support including a gusset is coupled to the graft material such that a transition apex of the main body transition stent is interposed between the gusset and the graft material, the transition apex being aligned with the transition region. The transition apex, which is susceptible to failure, is stabilized by the gusset in combination with a supporting ligament. The gusset and supporting ligament prevent flexing of the transition apex and the associated failure thereof.
