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 (Ø
