title: Evaluation of T-wave alternans in high-resolution ECG maps recorded during the stress test in patients after myocardial infarction.
abstract: BACKGROUND
  Recent studies point to analysis of T-wave alternans as a promising indicator of an increased risk of life-threatening ventricular arrhythmias. In this study the occurrence of T-wave alternans in the high-resolution ECGs recorded during the exercise stress test and scintigraphic tests (SPECT) in patients with ischemic heart disease was examined.
  
  
  METHODS
  The study group consisted of 33 patients after myocardial infarction. In the group of patients after myocardial infarction and with low left ventricular ejection fraction correlations of 70% between the test results of T-wave alternans and SPECT and 60% between the test results of T-wave alternans and stress test were found.
  
  
  RESULTS
  In the group of patients after myocardial infarction but with high left ventricular ejection fraction correlations were respectively 39% and 48%. The analysis of the electrocardiographic maps showed a strong dependence of this correlation on the T-wave alternans amplitude and location of the ECG measuring electrode on the chest. The results might suggest that in patients after myocardial infarction and at increased risk for sudden cardiac death T-wave alternans may also provide information about cardiac electrical instability associated with ischemia.
  
  
  CONCLUSIONS
  It can also be assumed that the position of the electrode where the highest level of the T-wave alternans was detected can indicate the location of the ischemic region of the heart.
authors: Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors: Dariusz
authors: D
authors: Janusek
authors: Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors: Michał
authors: M
authors: Kania
authors: Department of Cardiology, Medical University of Warsaw, Warsaw, Poland.
authors: Rajmund
authors: R
authors: Zaczek
authors: Department of Nuclear Medicine, Medical University of Warsaw, Warsaw, Poland.
authors: Małgorzata
authors: M
authors: Kobylecka
authors: Department of Nuclear Medicine, Medical University of Warsaw, Warsaw, Poland.
authors: Marek
authors: M
authors: Chojnowski
authors: Department of Nuclear Medicine, Medical University of Warsaw, Warsaw, Poland.
authors: Leszek
authors: L
authors: Królicki
authors: Department of Cardiology, Medical University of Warsaw, Warsaw, Poland.
authors: Grzegorz
authors: G
authors: Opolski
authors: Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors: Roman
authors: R
authors: Maniewski
keywords: T-wave alternans; arrhythmia; single-photon emission computed tomography; stress test; sudden cardiac death