title: Usefulness of the Poincaré maps in detection of T-wave alternans in precordial leads of standard ECG--a comparison with the spectral method.
abstract: BACKGROUND
  T-wave alternans (TWA) at microvolt level is considered as an important non-invasive risk factor for sudden death. Several methods are used to measure such repolarization variations, but each of them has some limitations. The purpose of our study is to assess the usefulness of Poincaré maps, a method based on nonlinear dynamics theory, in detection of repolarization abnormalities.
  
  
  METHODS
  In 30 postinfarction patients presence of TWA in precordial ECG leads was assessed by the spectral method (SM) and by the Poincaré maps (PM). Quantitative measures of both methods: alternans voltage (AV) and alternans distance (AD) were compared using linear regression.
  
  
  RESULTS
  Significant correlation between both measures (r = 0.92, p < 0.01) was found. The value of AD > or = 10 microV was accepted as significant for the presence of T-wave alternans.
  
  
  CONCLUSIONS
  Poincaré mapping seems to be a useful and simple method for detection of TWA. The alternans distance equal or greater than 10 microV can be considered as a level determinative for the presence of TWA.
authors.affiliation: Department of Cardiology, Institute of Cardiology, Medical University, ul. Sterlinga 1/3, 91-425 Łódź, Poland. jruta@robert.dofa.am.lodz.pl
authors.forename: J
authors.initials: J
authors.lastname: Ruta
authors.forename: P
authors.initials: P
authors.lastname: Strumiłło
mesh_terms: D000328:Adult; D000368:Aged; D003645:Death, Sudden / Q000209:etiology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009203:Myocardial Infarction / Q000473:pathology