[Prognostic significance of arrhythmias in acute myocardial infarction (author's transl)].

Ventricular arrhythmias represent a common precursor of ventricular fibrillation in acute myocardial infarction in man. Frequent ventricular ectopic beats (greater than 5/min), multifocal ectopic beats, ventricular bigeminy, ventricular salvoes, ventricular tachycardia, and the R-on-T phenomenon have been considered as warning arrhythmias. However, recent studies have given rise to some doubt concerning the value of warning arrhythmias as predictors of ventricular fibrillation. In many a case there is no warning arrhythmia prior to ventricular fibrillation or these arrhythmias do not fulfill the criteria of warning arrhythmias. In other cases the warning arrhythmias develop so briefly before ventricular fibrillation that no prophylactic measure can be instituted. Warning arrhythmias may occur at equal frequency in patients with and without consecutive ventricular fibrillation. This also applies to the R-on-T phenomenon as a warning arrhythmia and as the initiating mechanism of ventricular fibrillation. In nearly half the cases ventricular fibrillation is initiated by a late ventricular ectopic beat. In view of these data of the literature, the so-called warning arrhythmias seem to have lost their predictive value. They represent a common phenomenon in acute myocardial infarction in man. However, ventricular fibrillation may also occur without any prior ventricular arrhythmias, above all during the first day of acute myocardial infarction. The frequency of ventricular fibrillation decreases in the course of infarction. Therefore the time during acute myocardial infarction may be a better guide whether to institute prophylactic antiarrhythmic therapy than the occurrence of ventricular arrhythmias. To date, the beneficial effect of prophylactic administration of lidocaine has remained controversial though a recent double-blind study has strongly suggested that lidocaine is able to prevent ventricular fibrillation. If these results should be confirmed by others, this would ask for routine administration of lidocaine in each case with acute myocardial infarction during the first day.