Variability of ventricular premature contractions

Evaluation of antiarrhythmic drug effects with simultaneous analysis of single ventricular premature contractions, couplets and salvos

To improve the clinical value of ambulatory Holter electrocardiographic (ECG) monitoring as a tool of antiarrhythmic therapy control, a new statistical model was developed. In a patient group at increased risk of sudden cardiac death, the spontaneous variability of ventricular arrhythmias was assessed, with simultaneous consideration of single ventricular premature complexes, couplets and salvos. The study included 100 patients who suffered from coronary heart disease or idiopathic dilated cardiomyopathy and for whom greater than 30 ventricular premature complexes/h and couplets had been demonstrated on the last Holter ECG before the study. Between 3 and 12 Holter recordings were made for each patient in a drug-free state; the mean follow-up period was 260 days (maximum 1,403). The mean hourly values of the ectopic events (EE) were assessed separately for ventricular premature complexes, couplets and salvos. The spontaneous variability (SV) was calculated for single ventricular premature complexes, couplets and salvos as SV = log (EEday 2 + 0.01/EEday 1 + 0.01) and linked in one, two and three dimensions. Compared with the consideration of only one type of arrhythmia (one-dimensional model), the simultaneous use of two or three types of arrhythmia (two- or three-dimensional model) resulted in considerably lower reduction and aggravation rates as sufficient proof of drug effects. With control intervals up to 1 week, the one-dimensional model yielded reduction rates for ventricular premature complexes, couplets and salvos of -63%, -90% and -95%, respectively. In contrast, with the three-dimensional model, the rates were -28%, -72% and -88%. The corresponding aggravation values were +370, +1,114% and +2,189% versus +38%, +256% and +747%.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessing antiarrhythmic drug efficacy: multivariate considerations

The spontaneous variability of ventricular arrhythmias is the major problem in assessing antiarrhythmic drug efficacy. Efficacy is usually assessed on one form of ventricular premature beats, namely either single beats (VPC) or more complex forms like couplets or salvos. The reduction rates required to assume efficacy with a confidence of 95 per cent are 63 per cent for VPCs, 92 per cent for couples or 96 per cent for salvos. These rates are valid for two Holter electrocardiogram recordings within one week; otherwise the rates are higher and close to 100 per cent. In this paper we extend our ratio method for calculating these criteria to consider two or all three forms of ventricular premature beats simultaneously. The method is based on the first principal component. For use in practice we decided to calculate fixed criteria for each form of ventricular premature beats. For the combination of VPCs and couplets and a confidence level of 95 per cent, reduction rates of 42 per cent for VPC and 87 per cent for couplets are required. Both criteria must be fulfilled to assume the efficacy of a drug. These criteria are lower than those for each form alone. For all three forms together, reduction rates of 28, 72 and 88 per cent for VPC, couplets and salvos respectively are required.