title: Repolarization changes in a double-blind crossover study of dofetilide versus sotalol in the treatment of ventricular tachycardia.
abstract: The aim of this study was to determine whether a therapeutic response to Class III antiarrhythmic drugs is related to predictable changes in repolarization on the electrocardiogram (ECG). A group of 57 patients with ischemic heart disease and inducible ventricular tachycardia (VT) at electrophysiological study (EPS) were selected from a population enrolled in a randomized double-blind crossover study of dofetilide (500 micrograms bid) versus sotalol (160 mg bid). ECGs were analyzed blindly, and RR, QT (maximum value/12 leads), QTc (Bazett's formula), QT dispersion (QTmax-QTmin over 12 leads) and QTc dispersion, were calculated at baseline and on the third day of treatment (4 hours after dosing), when patients underwent EPS to test the effects of study drugs on VT inducibility.
  
  
  RESULTS
  At EPS 21 patients were responders to dofetilide and 22 to sotalol. On day 3, a significant increase in QT and QTc and decrease in QT and QTc dispersion, compared to baseline, was measured in responders and nonresponders, with both dofetilide and sotalol. No significant difference in QTc or QT dispersion between responders and nonresponders was observed in either treatment group. In conclusion, treatment with dofetilide and sotalol was associated with an increase in QT and QTc, and a decrease in QT and QTc dispersion. In contrast with previous reports, a differential effect on QT or QTc dispersion was not observed in drug responders versus nonresponders.
authors.affiliation: Institute of Cardiology, University of Bologna, Via Massarenti 9, 40138 Bologna, Italy. cardio1@almadns.unibo.it
authors.forename: G
authors.initials: G
authors.lastname: Boriani
authors.forename: M
authors.initials: M
authors.lastname: Biffi
authors.forename: N
authors.initials: N
authors.lastname: De Simone
authors.forename: L
authors.initials: L
authors.lastname: Bacchi
authors.forename: C
authors.initials: C
authors.lastname: Martignani
authors.forename: F
authors.initials: F
authors.lastname: Bitonti
authors.forename: R
authors.initials: R
authors.lastname: Zannoli
authors.forename: G
authors.initials: G
authors.lastname: Butrous
authors.forename: A
authors.initials: A
authors.lastname: Branzi
mesh_terms: D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications; D010627:Phenethylamines / Q000008:administration & dosage*; D013015:Sotalol / Q000008:administration & dosage*; D013449:Sulfonamides / Q000008:administration & dosage*; D017180:Tachycardia, Ventricular / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents; D010627:Phenethylamines; D013449:Sulfonamides; D013015:Sotalol; C063533:dofetilide