An implantable epicardial electrode assembly comprises electrode poles fixed on the heart having a large surface area and being multipolar and can at the same time be used as sensing and stimulating electrodes, wherein the electrode assembly has the shape of a tennis racket or is circular, elliptical, hexagonal, rectangular, oakleaf-shaped, star-shaped or cloverleaf-shaped and comprises at least two electrode poles which are arranged over a large surface area, and a further electrode arrangement which comprises at least one electrode pole and which is arranged between the large surface area electrode poles and further comprises a fixing element, wherein the defibrillation can take place between the mutually insulated poles of the electrodes, and wherein the stimulation of the heart can take place between one of the electrode poles and a pole of the electrode arrangement.
