Characteristics of ventricular tachycardia in ambulatory patients

This study analyzes 94 episodes of the ventricular tachycardia recorded in the ambulatory electrocardiograms of 23 patients with stable cardiac disease. The episodes were asymptomatic in 19 patients, and only one episode resulted in ventricular fibrillation. Eighty-five percent of the episodes occurred when the underlying heart rate was less than 100 beats/min, and 17 percent occurred during sleep. The rate of the ventricular tachycardia was between 120 and 180 beats/min in 78 percent of the episodes and showed a modest correlation with the underlying heart rate (r = 0.59, P less than 0.001). Only 14 of the 94 episodes were initiated by R on T premature ventricular contractions, and the mean prematurity index (+/- standard deviation) (R-R'/Q-T) for all episodes was 1.31 +/- 0.28. Episodes of ventricular tachycardia recorded during ambulatory electrocardiographic monitoring are usually self-limited and asymptomatic. They occur during ordinary nonexertional activity and are frequently initiated by late couples premature ventricular contractions.