title: Microvolt T-wave alternans amplifies spatial dispersion of repolarization in human subjects with ischemic cardiomyopathy.
abstract: In experimental models, spatial dispersion of repolarization (DOR) due to discordant cellular alternans predisposes to ventricular fibrillation. To test the hypothesis that microvolt T-wave alternans (MTWA) in humans causes spatial DOR, we measured Tpeak-Tend interval (Tpe) and Tpe/QT ratio, electrocardiographic indices of spatial DOR.
  
  
  
  Mean Tpe and Tpe/QT were compared in ischemic cardiomyopathy patients with positive and negative MTWA studies.
  
  
  
  MTWA was positive in 12 and negative in 24 patients. Tpe and Tpe/QT were higher in MTWA+ subjects compared to MTWA- subjects during exercise (64.5±6.8 vs. 54.9±8.7ms, p=0.001 and 0.218±0.03 vs. 0.177±0.02, p=0.001) but not at rest.
  
  
  
  Ischemic cardiomyopathy patients have increased Tpe and Tpe/QT when MTWA is induced during exercise, suggesting that MTWA causes increased spatial DOR in humans. Future studies are needed to determine if Tpe and Tpe/QT during exercise might predict increased risk of SCD alone or in combination with measurement of MTWA.
authors.affiliation: Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Tilak
authors.initials: T
authors.lastname: Pasala
authors.affiliation: Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Dettmer
authors.affiliation: Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Leo
authors.affiliation: Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Laurita
authors.affiliation: Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, OH, USA. Electronic address: ekaufman@metrohealth.org.
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Kaufman
mesh_terms: D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000209:etiology*; D009202:Cardiomyopathies / Q000150:complications* / Q000175:diagnosis*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications* / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Dispersion of repolarization; Ischemic cardiomyopathy; Microvolt T-wave alternans; Sudden cardiac death; Tpe/QT ratio; Tpeak-tend interval