Is the Degree of Arrhythmia Suppression a Predictor of Survival

: The effectiveness of an antiarrhythmic drug is judged by the degree of ventricular arrhythmia suppressed by the drug. It has been suggested that a certain degree of ventricular arrhythmia suppression should be targeted to prove efficacy. Targets used to define the effectiveness of an antiarrhythmic agent included an 80% reduction in the ventricular premature complexes (VPCs) and 90% suppression of nonsustained ventricular tachycardia (NVT) episodes or complete abolition of runs of sustained VT (SVT) [1]. Other dose-adjusted antiarrhythmic trials have attempted to achieve either isolated control of the PVCs of greater-than-or-equal70% [2--5] with the suppression of the high grades of arrhythmia such as couplets and NVT of >90% and 100%, respectively [2, 3]. Such targets of arrhythmia suppression were recommended to avoid errors encountered with the occurrence of the spontaneous variability of ventricular arrhythmia and to be confident that antiarrhythmic therapy has produced a true drug effect [6]. Presently, there is no evidence that suppression of these arrhythmias with type I antiarrhythmic drugs is likely to reduce sudden death [4, 6]. The survival of patients with frequent VPCs and high-grade forms (couplets [C], NVT) and organic heart disease is not dependent on the degree of arrhythmia suppression. The survival of patients with low LVEF of <40% and runs of NVT is improved and is similar to that of patients with good LVEF of greater-than-or-equal40%. Such a lack of correlation between arrhythmia suppression and survival might be a unique feature of the antifibrillatory drugs and might not be applied to the antiectopic drugs. If a high degree of arrhythmia suppression is not needed, lower targets of suppression may be necessary. Lower drug dosages may improve the risk--benefit ratio of antiarrhythmic treatment.