title: T-Wave morphology in short QT syndrome.
abstract: BACKGROUND
  Short QT syndrome (SQTS) is an inherited disorder characterized by a short QT interval and vulnerability to ventricular tachyarrhythmias. The diagnostic criteria for this syndrome are not well defined, since there is uncertainty about the lowest normal limits for the corrected QT (QTc) interval.
  
  
  OBJECTIVE
  The aim of this study was to determine whether T-wave morphology parameters are abnormal in short QT subjects and whether those parameters can help in the diagnosis of SQTS.
  
  
  RESULTS
  We describe three families (10 patients) with short QT intervals (QTc 310 +/- 32 ms). Seven subjects had suffered serious arrhythmic events and three were asymptomatic. T-wave morphology was assessed using the principal component analysis (PCA). QTc was significantly shorter and T-wave amplitude in lead V2 higher in the short QT subjects compared to healthy controls (n=149), (P < 0.001 for both). The total cosine of the angle between the main vectors of the QRS and T-wave loops (TCRT) was markedly abnormal among the symptomatic patients with short QT syndrome (n=7) (TCRT -0.14 +/- 0.55 vs 0.36 +/- 0.51, P=0.019). None of the three asymptomatic patients with short QT but without a history of arrhythmic events had an abnormally low TCRT.
  
  
  CONCLUSIONS
  Our observations suggest that patients with a short QT interval and a history of arrhythmic events have abnormal T-wave loop parameters. These electrocardiogram (ECG) features may help in the diagnosis of SQTS in addition to the measurement of the duration of QT interval from the 12-lead ECG.
authors.affiliation: Päijät-Häme Central Hospital, Lahti, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Anttonen
authors.forename: Juhani
authors.initials: J
authors.lastname: Junttila
authors.forename: Carla
authors.initials: C
authors.lastname: Giustetto
authors.forename: Fiorenzo
authors.initials: F
authors.lastname: Gaita
authors.forename: Eeva
authors.initials: E
authors.lastname: Linna
authors.forename: Mari
authors.initials: M
authors.lastname: Karsikas
authors.forename: Tapio
authors.initials: T
authors.lastname: Seppänen
authors.forename: Juha S
authors.initials: JS
authors.lastname: Perkiömäki
authors.forename: Timo H
authors.initials: TH
authors.lastname: Mäkikallio
authors.forename: Ramon
authors.initials: R
authors.lastname: Brugada
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology*; D002648:Child; D004562:Electrocardiography; D005260:Female; D005387:Finland; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D013577:Syndrome