The present invention relates to implantable endoluminal prosthesis for preventing stroke. The endoluminal prosthesis (1) consists of a braided framework (20) defining a cylindrical lumen (21) devoid of impermeable membrane. Said braided framework (20) is self-expandable comprising a plurality of layers (22, 23, 24) of wires (25) made of biocompatible material. Each layer forms a mesh. The meshes form a lattice with a plurality of wires (2) of given layers (22, 23, 24). The lattice defines polygonal opening units (26) when observed normal to a wall of the implantable endoluminal prosthesis (1). The diameter (Ø25) of wire (25) being at least 30 μm and at most 150 μm, the mean diameter (Ø27) of the inscribed circle (27) of the polygonal opening units (26) being at least 75 μm and at most 200 μm in fully expanded state. The braided framework (20) consists of at least 128 and at most 512 wires (25). The ratio (T1/Ø25) of the thickness (T1) of a wall of said implantable endoluminal prosthesis (1) to the diameter (Ø25) of wire (25) is at least 3.0. In a fully expanded state, the surface coverage ratio (SCR) of said braided framework (20) is more than 50% and less than 90%.