Various stent-graft systems for treatment of medical conditions are disclosed. In one embodiment, an exemplary stent-graft system may be used for endovascular treatment of a thoracic aortic aneurysm. The stent-graft system (800) comprises proximal (802) and distal (822) components, each comprising a graft (805, 825) having proximal and distal ends, where upon deployment the proximal and distal components at least partially overlap with one another to provide a fluid passageway therebetween. The proximal component comprises a proximal stent (804) having a plurality of proximal and distal apices connected by a plurality of generally straight portions, where a radius of curvature of at least one of the proximal apices greater than the radius of H is curvature of at least one of the distal apices. The distal component comprises a proximal z- stent (830a) coupled to the graft (825), where the proximal end of the graft comprises at least a scallop (845) formed therein that generally follows the shape of the proximal z- stent. Further, the distal component may comprise at least one z- stent (834) coupled to the distal end of the graft and extending distally therefrom that reduces proximal migration of the distal component.