An electrode assembly for an active implantable medical device can be delivered by catheter but expands to become a paddle electrode once implanted. The electrode assembly comprises a support member carrying wires for electrically connecting a control unit to electrodes of the electrode assembly. At least one, and usually two resilient deformable paddle wings are mounted to the support member. The paddle wings can be furled close to the support member under a deformation force to permit implantation via an introducer. The paddle wings resiliently unfurl away from the support member upon release of the deformation force. The paddle wings bear rows and columns of electrodes, and the electrode assembly as a whole has sufficient longitudinal rigidity for implantation via an introducer.