[A new method for the evaluation of the success of anti-arrhythmic drug therapy and a paradoxical drug-induced arrhythmogenic effect in individual patients].

The aim of this study was to develop standards to define both antiarrhythmic drug efficacy and a drug-induced arrhytmogenic effect. In 45 patients with frequent and complex ventricular tachyarrhythmias 3 continuous 24-hour Holter recordings were performed. The spontaneous variability of ventricular premature beats and ventricular pairs was calculated using a new statistical method (transformation model). If two 24-hour Holter monitoring periods, one period before and the other with antiarrhythmic therapy, are compared, at least 75% reduction of ventricular premature beats and 90% reduction of ventricular pairs is necessary to be reasonably certain that one is measuring a drug response rather than spontaneous arrhythmia reduction (p less than or equal to 0.05). On the other hand, drug-induced aggravation can be assumed if ventricular premature beats and ventricular pairs have increased by more than 144% and 227%, respectively (p less than or equal to 0.05).