A method of delivering a stent-graft includes mounting the stent-graft on a pushrod； radially constraining the stent-graft within a sheath； securing a crown portion of the stent-graft to the pushrod with a retainer structure of a stent-graft retainment system； retracting the sheath to expose the crown portion of the stent-graft； and further retracting the sheath to cause the retainer structure to release the crown portion from the pushrod thus deploying the stent-graft. The retainer structure releases the stent-graft automatically as a result of the retraction of the sheath.
