title: Short-term vs. long-term heart rate variability in ischemic cardiomyopathy risk stratification.
abstract: In industrialized countries with aging populations, heart failure affects 0.3-2% of the general population. The investigation of 24 h-ECG recordings revealed the potential of nonlinear indices of heart rate variability (HRV) for enhanced risk stratification in patients with ischemic heart failure (IHF). However, long-term analyses are time-consuming, expensive, and delay the initial diagnosis. The objective of this study was to investigate whether 30 min short-term HRV analysis is sufficient for comparable risk stratification in IHF in comparison to 24 h-HRV analysis. From 256 IHF patients [221 at low risk (IHFLR) and 35 at high risk (IHFHR)] (a) 24 h beat-to-beat time series (b) the first 30 min segment (c) the 30 min most stationary day segment and (d) the 30 min most stationary night segment were investigated. We calculated linear (time and frequency domain) and nonlinear HRV analysis indices. Optimal parameter sets for risk stratification in IHF were determined for 24 h and for each 30 min segment by applying discriminant analysis on significant clinical and non-clinical indices. Long- and short-term HRV indices from frequency domain and particularly from nonlinear dynamics revealed high univariate significances (p < 0.01) discriminating between IHFLR and IHFHR. For multivariate risk stratification, optimal mixed parameter sets consisting of 5 indices (clinical and nonlinear) achieved 80.4% AUC (area under the curve of receiver operating characteristics) from 24 h HRV analysis, 84.3% AUC from first 30 min, 82.2 % AUC from daytime 30 min and 81.7% AUC from nighttime 30 min. The optimal parameter set obtained from the first 30 min showed nearly the same classification power when compared to the optimal 24 h-parameter set. As results from stationary daytime and nighttime, 30 min segments indicate that short-term analyses of 30 min may provide at least a comparable risk stratification power in IHF in comparison to a 24 h analysis period.
authors.affiliation: Department of Medical Engineering and Biotechnology, University of Applied Sciences Jena, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Voss
authors.affiliation: Department of Medical Engineering and Biotechnology, University of Applied Sciences Jena, Germany.
authors.forename: Rico
authors.initials: R
authors.lastname: Schroeder
authors.affiliation: Biomedical Engineering Research Centre, Universitat Politècnica de Catalunya Barcelona, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Vallverdú
authors.affiliation: Department of Medical Engineering and Biotechnology, University of Applied Sciences Jena, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Schulz
authors.affiliation: Department of Electrocardiology, Sterling Memorial University Hospital Lodz, Poland.
authors.forename: Iwona
authors.initials: I
authors.lastname: Cygankiewicz
authors.affiliation: Servicio de Cardiología, Puerta del Mar University Hospital Cádiz, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Vázquez
authors.affiliation: Institut Català Ciències Cardiovasculars, Hospital Sant Pau Barcelona, Spain.
authors.forename: Antoni
authors.initials: A
authors.lastname: Bayés de Luna
authors.affiliation: Biomedical Engineering Research Centre, Universitat Politècnica de Catalunya Barcelona, Spain.
authors.forename: Pere
authors.initials: P
authors.lastname: Caminal
keywords: daytime; heart rate variability; ischemic cardiomyopathy; long-term; nighttime; nonlinear dynamics; risk stratification; short-term