A multi-lumen stent assembly (100) suitable for deployment in a bifurcated vessel, said assembly comprising a self-expandable main body component (200) able to expand from a radially compressed state in a delivery configuration to a radially expanded state and two lumen extensions (300), each lumen extension comprising a tip portion (301) able to be inserted into one of the lumens of the double-barrelled portion (208) from the distal end (202) of the main body component (200). The main body component (200) has a proximal end (201) configured to be placed toward the heart and a distal end (202) configured to be placed toward away from the heart. The main body component (200) comprises a main body portion (203) at the proximal end (201) of main body component (200), a concaved portion (206) towards the distal end (202) of main body component (200), and a transition portion (205) extending between the distal end of the main body portion (203) and a proximal end of the concaved portion (206). The main body portion (203) comprises a lumen (204) in a cylindrical form with a circular cross-section and a constant diameter. the concaved portion (206) comprises a double-barrelled portion (208) having two lumens (211). A cross-section of the transition portion (205) evolving from a circular shape towards the proximal end of the transition portion (205) to an elliptical shape towards the distal end of the transition portion (205), a larger diameter of this shape being in the central plane (CP).
