Transcatheter device for the treatment of calcified native heart valve leaflets comprising an outer hollow shaft (5), an inner hollow shaft (4) slidingly contained within said outer shaft (5) and an axle body (6) slidingly contained within said inner shaft (4); wherein the device comprises a commissure debridement system (7), located at the distal end of the axle body (6), that is made of at least two radially expandable arms (7) that are adapted to be inserted in and aligned with native commissures.