The natural history of benign and potentially malignant ventricular arrhythmias with special reference to nonsustained ventricular tachycardia

Ambulatory ECG recordings are routinely used to identify patients at increased risk of sudden cardiac death and to monitor changes in ventricular arrhythmias during antiarrhythmic drug therapy. The arrhythmia frequency established during the initial baseline has previously been reported to change during a second placebo monitoring period in patients with non-life-threatening ventricular arrhythmias, but the extent to which this applies to patients with nonsustained ventricular tachycardia has not been examined. To extend these observations to patients with potentially lethal ventricular arrhythmias, we studied 53 patients enrolled in one of two investigational antiarrhythmic drug trials that introduced a second single-blind placebo period (placebo-pulse) an average of 16 months after successful arrhythmia suppression. Thirty-eight of the 53 patients had runs of nonsustained ventricular tachycardia recorded during the initial baseline (placebo I) period, with 63% averaging ≥10 runs per day. There was a marked reduction in the arrhythmia frequencies between the two placebo periods: 55% for ventricular premature beats, and 77% for pairs (p < 0.001, respectively). Of the 38 patients with nonsustained ventricular tachycardia, there was a 72% reduction (892 ± 531 vs 245 ± 18 runs of VT/day, placebo I vs II; p = 0.0001), with 32% having total suppression of nonsustained ventricular tachycardia during the second placebo period. The results of this trial extend our previous observations of long-term spontaneous changes in arrhythmia frequency to patients with symptomatic, potentially lethal ventricular arrhythmia and support the recommendation for periodic reassessment of baseline arrhythmia frequency to determine the continued need for antiarrhythmic therapy. These observations cannot be extended to patients with life-threatening arrhythmias (sustained ventricular tachycardia, cardiac arrest, or ventricular fibrillation).