A multi-lumen stent assembly (100) suitable for deployment in a bifurcated vessel comprising a main vessel and at least two branches, said assembly comprising: (i) a self-expanding main body component (200) capable of expanding from a radially compressed state in a delivery configuration to a radially expanded state, the main body component (200) having a proximal end (201) configured to extend away from the branches of the bifurcated vessel and a distal end (202) configured to extending towards the branches of the bifurcated vessel, and extending along an axis and comprising: - at the proximal end (201) of the component (200) of the main body, a main body part (203) comprising a lumen (204) cylindrical in shape with a circular cross section and a constant diameter； - towards the distal end (202) of the component (200) of the main body, a concave part (206) comprising a double cylinder part (208), the middle lines of the concave part (206) being concave along the longitudinal axis of the main body component (200) and defining two opposing flanges (210) with an interior of the concave part (206), partially making contact with each flange (210) with the other flange (210), defining the two opposite flanges (210) two lumens (211) of the double cylinder part (208), each of the two lumens (211) extending along an axis, the axes of the two lumens (211) defining a central plane (CP) ) which also comprises the axis of the component (200) of the main body； (ii) two extensions (300) of lumen, each lumen extension comprising a tip portion (301) capable of being inserted into one of the lumens of the double cylinder part (208) from the distal end (202) of the component (200) of the main body； - the main body component (200) further comprises a transition part (205) extending between the distal end of the main body part (203) and a proximal end of the concave part (206), evolving a cross section of the transition part (205) from a circular shape towards the proximal end of the t
