Antiarrhythmic drugs have systematically failed to improve--or have even worsened prognosis--when given prophylactically to "high-risk" patients without previous spontaneous sustained ventricular arrhythmias. In patients who have had > or = 1 episode(s) of near sudden cardiac death or sustained ventricular arrhythmias, randomized studies against placebo have been considered unethical. Therefore, no information exists on the value of treatment with antiarrhythmic drugs in the prevention of sudden death in these patients. Sudden death is quite predictable and almost expected in some situations. The number of "very high risk" patients is small, but the incidence of sudden death among them is very high. A prophylactic implantable cardioverter-defibrillator (ICD) can be easily justified in them. Unfortunately, the greatest absolute number of sudden deaths occurs in patients from a very large population with a rather low risk for sudden death. Truly unexpected cardiac death is most frequently caused by the first acute ischemic event in a previously asymptomatic individual. While the causes of sudden cardiac death are multiple, the final link is frequently the same: ventricular fibrillation. This arrhythmia can be effectively recognized and treated by an ICD, irrespective of its initiating cause. The time when an ICD will be given prophylactically to a truly asymptomatic individual may never come, but there is an urgent need to implant this device prophylactically in patients who are clearly at risk for sudden death. There are medical, ethical, statistical, technical, practical, financial, and even philosophical obstacles involved in the concept of a prophylactic ICD, but they can be solved, because this therapy is effective. Deciding on the benefits of a prophylactic ICD is a probabilistic issue analogous to deciding on mass vaccination against a preventable infection. To the political community, the decision to accept a prophylactic ICD is too much a matter of expenses, because the benefits may not seem that obvious to them. To the device industry, the cleaves between doctors and politicians have to be the best stimuli to come along with cost-effective technology acceptable to both sides.