In an aspect of the invention an ablation catheter for atrial fibrillation ablation is proposed which is arranged for creating a transmural lesion of operative tissue of a subject, comprising: a flexible epicardial catheter unit comprising a plurality of magnetic elements and a plurality of ablation elements, said magnetic elements being arranged in a row at regular intervals along a longitudinal direction of said flexible epicardial catheter unit and further comprising a top magnetic element located at a distal end of said flexible epicardial catheter unit arranged for magnetic coupling of said a top magnetic element with at least one of lateral magnetic elements disposed laterally along said longitudinal direction of said flexible epicardial catheter unit, said ablation elements being arranged in a row at regular intervals along a longitudinal direction of said flexible epicardial catheter unit； a flexible endocardial catheter unit comprising a plurality of magnetic elements and a plurality of ablation elements, said magnetic elements being arranged in a row at regular intervals along a longitudinal direction of said flexible epicardial catheter unit, said ablation elements being arranged in a row at regular intervals along a longitudinal direction of said flexible epicardial catheter unit； said flexible epicardial catheter unit further comprising an auxiliary flexible epicardial catheter unit comprising an auxiliary catheter strip comprising a plurality of magnetic elements and a plurality of ablation elements and at least one top magnetic element located at a distal end of said auxiliary catheter strip, said auxiliary catheter strip being arranged to be contained in said flexible epicardial catheter unit and arranged for unfolding said auxiliary catheter strip from, and in a direction perpendicular to said flexible epicardial catheter unit, for magnetic coupling of said at least one top magnetic element with at least one of said lateral magnetic elements of said
