[Anti-arrhythmic drug prevention of sudden cardiac death--the status after the CAST study].

Sudden cardiac death is caused by ventricular tachyarrhythmias. Therefore, antiarrhythmic drugs have been widely used in the prophylaxis of this lethal event. However, all studies using "classical" antiarrhythmic drugs (class 1) for this purpose have shown an enhanced mortality in the patients treated. One of the major causes for these disappointing results are probably proarrhythmic effects, which are especially observed in patients with reduced left ventricular function. Obviously a normal Holter ECG during the titration phase cannot exclude proarrhythmic events during long-term follow-up. In addition, the suppression of ventricular premature beats by an antiarrhythmic agent seems not to be an useful criterium as far as the prophylaxis of sudden death is concerned. The crucial prerequisit for the induction of the lethal arrhythmia is the "arrhythmogenic substrate" which clinically can only incompletely analysed by recording of late potentials or programmed ventricular stimulation. From the therapeutical point of view we need drugs which can modulate this arrhythmogenic substrate i.e. antifibrillatory acting drugs and not antiarrhythmic drugs in the classical sense. Beta blockers and class 3 drugs are the first step in this direction.