title: Towards a better understanding of QT interval variability.
abstract: The International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) Guideline E14 recommends 'Thorough QT Study' as a standard assessment of drug-induced QT interval prolongation. At the same time, the value of drug-induced QTc prolongation as a surrogate marker for risk of life-threatening polymorphic ventricular tachycardia known as torsades des pointes remains controversial. Beat-to-beat variability of QT interval was recently proposed as an alternative metric. The following review addresses mechanisms of beat-to-beat QT variability, methods of QT interval variability measurements, and its prognostic value in clinical studies.
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Larisa G
authors.initials: LG
authors.lastname: Tereshchenko
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Carnegie 592, 600 N. Wolfe St., Baltimore, MD 21287, USA.
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Berger
keywords: QT interval; QT variability; drug safety; ventricular tachyarrhythmias
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