The suppression by antiarrhythmic drugs of ventricular premature beats, pairs and salvos is frequently not associated with a suppression of ventricular tachycardia or fibrillation in the same patient. The evaluation of antiarrhythmic drugs must therefore distinguish between antiectopic, anti-reentry and anti-fibrillatory efficacy Clinical methods such as Holter monitoring and programmed electrical stimulation which only allow the validation of anti-ectopic or anti-reentry efficacy present a major problem in the evaluation of antiarrhythmic drugs. Anti-fibrillatory drug efficacy cannot be evaluated by clinical methods.