Variability of ventricular premature complexes and mortality risk.

A method using a parameter from the field of nonlinear dynamics to quantify the variability of ventricular premature complexes (VPCs) is presented. One hundred patients with coronary artery disease and >=10 VPCs/hour were included in the study. The BR intervals were plotted in a three-dimensional artificial phase space, and the structures in phase space were quantified by the local scaling indices, [alpha]. In the frequency distribution histogram. n([alpha]), for each patient, the maximum of the ventricular ectopies [alpha]_VPC, adjusted to the VPC frequency, was assessed; [alpha]_VPC was used as the risk indicator. Endpoints were total mortalitv and sudden cardiac death. During follow-up (mean 3.1 years). 28 out of 100 patients died, 16 suddenly; [alpha]_VPC had a significant prognostic impact and was independent from other risk indicators, such as left ventricular ejection fraction (LVEE). Patients who died during follow-up were characterized by a high [alpha]_VPC. The optimal discrimination of high risk patients and low risk patients occurred at[alpha]_VPC 3.0. After 4 years, the survival rate of patients with a [alpha]_VPC >.0 was 59%, in contrast to 97% in patients with [alpha]_VPC. As to the sudden death mortality, the .survival rates were 74% and 97%. respectively. The difference between the groups were significant for both endpoints. Patients with an increased VPC variability (i.e.. [alpha]_VPC > 3.0) were at enhanced risk of sudden death and total mortality risk; [alpha]_VPC was independent from other risk indicators such as the LVEE or heart rate variability parameters. [ABSTRACT FROM AUTHOR]