title: Effects of antiarrhythmic drugs on QT interval dispersion--relationship to antiarrhythmic action and proarrhythmia.
abstract: Class IA, IC, and III antiarrhythmic drugs prolong ventricular repolarization (VR) which is manifest as QT interval prolongation on the surface electrocardiogram. These drugs may prolong VR in a spatially heterogeneous manner which results in increased dispersion of VR. This may be manifest as increased QT interval dispersion. Antiarrhythmic drug-induced decreases in QT interval dispersion are associated with antiarrhythmic efficacy in patients with the long QT syndrome and in patients with sustained ventricular tachycardia. Antiarrhythmic drug-induced increases in QT interval dispersion are associated with ventricular proarrhythmia secondary to torsades de points ventricular tachycardia. A number of factors may modulate the effects of antiarrhythmic drugs on dispersion of VR, including the disease state, transient ischemia, electrolyte abnormalities, changes in autonomic tone, and hemodynamic stress.
authors.affiliation: Division of Cardiology, Foothills Hospital, Calgary, Alberta, Canada.
authors.forename: A M
authors.initials: AM
authors.lastname: Gillis
mesh_terms: D000889:Anti-Arrhythmia Agents / Q000494:pharmacology* / Q000627:therapeutic use; D004562:Electrocardiography / Q000187:drug effects*; D006331:Heart Diseases / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans
chemical_list: D000889:Anti-Arrhythmia Agents