Despite all advances in the diagnostic and therapy of cardiovascular diseases the mortality from malignant ventricular tachyarrhythmias is still a major health problem. In addition to established therapeutic strategies in the prevention of sudden cardiac death such as antiarrhythmic drug treatment, catheter ablation or antiarrhythmic surgery the implantable cardioverter/defibrillator was introduced to clinical practice in 1980. The number of 50,000 overall implants reflects the current clinical status of the therapy with implantable cardioverters/defibrillators. Significant technical improvements in the defibrillator therapy may contribute to an increase in therapy acceptance. These advances include the introduction of nonthoracotomy lead systems, enhanced defibrillation efficacy, full programmable devices providing tiered electrical therapy, improved diagnostic Holter functions and enhanced arrhythmia detection algorithms. The major present goals of defibrillator therapy are, detection and termination of malignant ventricular tachyarrhythmias, reduction of sudden cardiac death, reduction in patient's mortality and improvement in quality of life. The efficacy and safety of defibrillator therapy to prevent sudden arrhythmic death has been proven in several large clinical investigations. The annual sudden cardiac death mortality is < 2% even in high-risk patient populations. Compared to sudden cardiac death rate there is a much higher rate of overall cardiac mortality because a defibrillator is not able to prevent nonarrhythmic cardiovascular deaths. There is a clinical impression that cardiovascular mortality is lower in patients treated with an implantable cardioverter/defibrillator compared to patients treated with other therapies. However there are no results from controlled studies providing scientific evidence that defribillator therapy can reduce overall cardiovascular mortality.(ABSTRACT TRUNCATED AT 250 WORDS)