title: T-wave alternans phase following ventricular extrasystoles predicts arrhythmia-free survival.
abstract: OBJECTIVE
  The purpose of this study was to assess the value of T-wave alternans (TWA) following ventricular extrasystoles in predicting arrhythmia-free survival.
  
  
  BACKGROUND
  Stratifying risk for sudden death in patients with coronary disease and moderate left ventricular (LV) dysfunction remains a challenge. We hypothesized that, in such patients, a discontinuity in beat-to-beat T-wave alternation (TWA phase reversal) following single ventricular extrasystoles reflects transiently exaggerated repolarization dispersion, and predicts spontaneous ventricular arrhythmias.
  
  
  METHODS
  We studied 59 patients with ischemic LV dysfunction (mean LV ejection fraction 38.7 +/- 5.3%) and nonsustained ventricular tachycardia undergoing programmed stimulation. TWA was computed spectrally from the ECG during ventricular pacing, and TWA phase reversal was reflected by a discontinuity in T-wave oscillation after single ventricular extrasystoles.
  
  
  RESULTS
  Patients induced into ventricular arrhythmias (n = 36) had greater TWA magnitude (V(alt): 6.60 +/- 6.46 microV vs 2.61 +/- 1.97 microV; P = .001) and more frequent TWA phase reversal (62.1% vs 44.4%; P = .02) than those who were not (n = 23). During a mean follow-up of 36 +/- 12 months, positive TWA (V(alt) > or =1.9 microV) and TWA phase reversal both (P < .05) predicted events (all-cause mortality, ventricular tachycardia, ventricular fibrillation). Univariate predictors of arrhythmia-free survival were TWA phase reversal (P < .005), positive TWA (P < .05), age (P = .008), and LV mass index (P = .043). On multivariate analysis, only TWA phase reversal and age predicted events; if TWA phase was excluded, only positive TWA and age predicted events.
  
  
  CONCLUSIONS
  Phase reversal in TWA following ventricular extrasystoles predicts spontaneous ventricular arrhythmias and all-cause mortality in patients with moderate ischemic LV dysfunction and was a better predictor than positive TWA or programmed ventricular stimulation.
authors.affiliation: University of California, San Diego, 92161, USA. snarayan@ucsd.edu
authors.forename: Sanjiv M
authors.initials: SM
authors.lastname: Narayan
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Smith
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Schechtman
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Lindsay
authors.forename: Michael E
authors.initials: ME
authors.lastname: Cain
mesh_terms: D000368:Aged; D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D005117:Cardiac Complexes, Premature / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D018572:Disease-Free Survival; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016019:Survival Analysis