An external automatic defibrillator including an attachment device that can be externally attached and carried by a patient, an identification device for detecting an abnormal event in the cardiac activity, which can be treated by an electric shock, as well as a defibrillator allowing to exert a shock upon the patient after having detected the abnormal event. In order to ensure reliable functioning over a longer period of time, the identification device is configured so that the identification device can detect an abnormal event in an interval of not more than 90 seconds or one minute.