A young man who underwent mitral valve replacement with a Medtronic-Hall valve, along with resuspension of the papillary muscles using Gore-Tex sutures, presented with recurrent episodes of syncope that began four months after surgery. Echocardiography revealed a filamentous structure that was entangling intermittently in the prosthesis and causing intermittent electromechanical dissociation. The patient recovered spontaneously after a three-weeks symptomatic period, with no subsequent evidence of the filamentous structure and electromechanical dissociation.