title: Relationship between duration of repolarisation and T wave amplitude in patients with positive or negative T wave alternans.
abstract: BACKGROUND
  Experimental studies documented the relationship between T wave alternans (TWA) and duration of refractoriness. To date, association between TWA and QT interval on standard ECG has not been examined. Aim. To assess the relationship between TWA and QT interval.
  
  
  METHODS
  The study group consisted of 70 patients (57 males, mean age 56+/-16 years) with implantable cardioverterdefibrillator (ICD). TWA was measured using a high-resolution ECG obtained from surface orthogonal bipolar XYZ leads and analysed using a Fast Fourier transform. All recordings were performed during ventricular pacing at 100 betas/min. Correlation between T wave amplitude (T max) and QT interval (measured from R wave to T max) was calculated.
  
  
  RESULTS
  TWA was found in 18 patients. In this group of patients, there was a significant positive correlation between Tmax and QT (r = 0.766), whereas in patients with negative TWA no such correlation was detected.
  
  
  CONCLUSIONS
  (1) Positive correlation between QT and T max probably depicts the relationship between T wave amplitude and duration of repolarisation, which is associated with TWA; (2) methods used for T wave localisation, based on the identification of Q wave (with possible QT-RR correction) overestimate TWA due to periodic changes (with TWA frequency) in location of T wave in the analysed window; and (3) these results provide new insights in the genesis of TWA.
authors.affiliation: Institute of Radioelectronics, Warsaw University of Technology, Warsaw, Poland.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Janusek
authors.forename: Stefan
authors.initials: S
authors.lastname: Karczmarewicz
authors.forename: Zdzisław
authors.initials: Z
authors.lastname: Pawłowski
authors.forename: Andrzej
authors.initials: A
authors.lastname: Przybylski
authors.forename: Kinga
authors.initials: K
authors.lastname: Gościńska-Bis
authors.forename: Andrzej
authors.initials: A
authors.lastname: Lubiński
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Zajac
authors.forename: Dagmara
authors.initials: D
authors.lastname: Urbańczyk
authors.forename: Artur
authors.initials: A
authors.lastname: Filipecki
authors.forename: Beata
authors.initials: B
authors.lastname: Romanik
authors.forename: Ilona
authors.initials: I
authors.lastname: Kowalik
mesh_terms: D000328:Adult; D000368:Aged; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged