Frequent ventricular ectopic activity without underlying cardiac disease: Analysis of 45 subjects

Forty-five subjects, aged 2 weeks to 62 years, who presented with frequent (> 100/day) ventricular ectopic beats (VEBs) and without evidence of underlying cardiac disease were studied. The spectrum of ventricular dysrhythmia was assessed by 24-hour ambulatory electrocardiography and exercise tolerance test. Sinus rhythm was the prevailing rhythm in all subjects. VEB frequency averaged 444 ± 454 per hour (range 0 to 1,863) over the 24-hour monitoring period and was not significantly different during waking or sleeping periods. There was no simple correlation of VEB frequency with prevailing sinus rate (r = - 0.0006; p = not significant [NS]). The prevalence of complex VEBs (multiform, R-on-T and repetitive) was relatively high (18 of 45 patients), and was equally distributed about the median VEB frequency of 314 VEBs/hour (7 of 18 versus 11 of 18; NS). Of the 43 subjects who had exercise tests, 37 had VEBs during the preexercise rest phase, compared with only 11 at peak exercise (p < 0.0001). To assess the short-term natural history of the VEBs, 27 subjects had repeat clinical examinations and 24-hour electrocardiograms at a mean interval of 8 months. All remained well. Although there was considerable individual temporal variability of VEB frequency in this subgroup, there was no significant change in group mean values (415 ± 409 VEBs/hour initially versus 401 ± 383 VEBs/hour at follow-up study; NS). The relative temporal constancy of VEB frequency in the group as a whole was also reflected in a high linear correlation of VEB frequency at initial and follow-up studies (r = 0.816; p < 0.001). Follow-up in 2 other patients revealed that 1 died suddenly (age 4 months) of indeterminate cause in the setting of sudden infant death syndrome, and 1 (age 36 years) had symptomatic, sustained ventricular tachycardia. The other 16 subjects remain well a mean of 22 months after the initial study. Thus, patients who present with frequent VEBs and no evidence of underlying anatomic cardiac disease have a high prevalence of complex VEBs. Despite marked individual temporal variability of VEB frequency in these patients, the VEBs tend to persist over the short-term period. Most, however, remain asymptomatic and clinically well, and the risk of clinical progression of their disease, although present, appears small. Further studies are required to determine the long-term natural history of these patients and the origin of their ventricular dysrhythmia, with a particular goal of identifying those at risk.