Automatic implantable defibrillator therapy has changed the approach to life-threatening ventricular tachycardia completely and essentially improved survival after aborted sudden cardiac death. Since the first implantation of a defibrillator in 1980, 20,000 patients have received such a device. Nonetheless, in Germany still too many patients die of sudden cardiac death because defibrillator therapy fails to be known enough and keeps not being made use of (no more than 1,000 implants to date). In this group of patients characterized by poor ventricular function, antiarrhythmic drug therapy proved to be unreliable or even dangerous in many cases, while electrophysiologically-guided surgical interventions use to be impossible. The introduction of the implantable defibrillator enabled the incidence of sudden cardiac death to be reduced to about 2% during the first year after implant, and to 5% in the third year, respectively. In most centers with more extensive experience in defibrillator implantations, operative mortality is about 2-3%. Long-term results with defibrillator patients are controlled by the course of the underlying disease, which is coronary artery disease with large scars due to infarction in some 75% of cases. In a large group of about 10,000 patients, total mortality has been calculated to be 15% after three years. Defibrillator systems of the latest generation offer multiple programmability of tachycardia identification parameters and permit differentiated modification of therapeutic intervention. Defibrillator therapy has now been improved essentially by the introduction of endocardial lead systems and, in addition, by the defibrillator being combined with an antitachycardia pacing system.(ABSTRACT TRUNCATED AT 250 WORDS)