Spontaneous variability of premature ventricular complexes and its significance in assessing anti-arrhythmic drug...

Using ambulatory electrocardiography (AE), the spontaneous variability in 40 cases of chronic stable premature ventricular complexes (PVCs) was studied. The mean hourly PVC frequencies over 24 hours ranged 2-1 682. When analysing pooled data, there was significant variance between different monitoring periods and between patients as well. The most appropriate duration of AE recording was found to be 24 hours. The lower the mean hourly PVC frequencies, the bigger the coefficient of variation. Using linean regression analysis, the reduction of PVC frequency attributable to spontaneous variability with 95% confidence intervals ranged from 59 to 81% being related to the number of hospitalization days. Clinically, to evaluate antiarrhythmic drug efficacy, one should assess the reduction in PVC frequency of spontaneous variability advance, and a greater reduction rate is required to be considered as true drug effect. The previous fixed standard for assessing an antiarrhythmic drug response is no longer advisable.