title: Comparative usefulness of beat-to-beat QT dispersion and QT interval fluctuations for identifying patients with organic heart disease at risk for ventricular arrhythmias.
abstract: The comparative usefulness of 10 min of beat-to-beat 12-lead QT dispersion (QTd) and QT interval variability index (QTVI) analysis for identifying patients with organic heart disease (OHD) at risk for ventricular arrhythmias was assessed in 86 subjects: 54 had OHD without a history of ventricular arrhythmias, 15 had OHD with documented ventricular tachycardia, and there were 17 controls. The following parameters were analyzed among the groups: (1) the average QTd (mean QTd), (2) the difference between the maximum and minimum QTd observed over the recording time (QTd variation), (3) the maximum difference of QTd between consecutive beats (QTd maximum), (4) the QTd standard deviation (QTd variability), and (5) QTVI, calculated in lead I or II according to an established formula: log 10 [(QTv/QTm2) / (HRv/HRm2)]. All the analyzed parameters were significantly increased in the patients with and without ventricular tachycardia when compared with the controls. QTd variation, QTd maximum and QTd variability were the only variables that remained significantly increased in the group of patients with documented ventricular tachycardia, compared with those without arrhythmia. Thus, beat-to-beat fluctuations of both the QT interval and QTd may be markers of temporal electrical instability in patients with OHD.
authors.affiliation: Department of Cardiovascular and Respiratory Medicine, Kobe University Graduate School of Medicine, Japan.
authors.forename: Erdulfo J
authors.initials: EJ
authors.lastname: Galeano
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yoshida
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Ohnishi
authors.forename: Katsunori
authors.initials: K
authors.lastname: Okajima
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ishida
authors.forename: Hidetsuna
authors.initials: H
authors.lastname: Kitamura
authors.forename: Shinya
authors.initials: S
authors.lastname: Kubo
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yokoyama
mesh_terms: D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000209:etiology; D016022:Case-Control Studies; D004562:Electrocardiography / Q000379:methods* / Q000592:standards; D005260:Female; D006331:Heart Diseases / Q000150:complications / Q000175:diagnosis*; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology