title: Changes and predictive value of dispersion of repolarization parameters for appropriate therapy in patients with biventricular implantable cardioverter-defibrillators.
abstract: BACKGROUND
  The impact of cardiac resynchronization therapy (CRT) on dispersion of repolarization is controversial. The benefit of CRT on sudden cardiac death has been demonstrated only after 3 years follow-up.
  
  
  OBJECTIVE
  The purpose of this study was to explore the immediate effect of CRT on dispersion of repolarization and to define the value of dispersion of repolarization parameters as predictors of appropriate implantable cardioverter-defibrillator (ICD) therapy.
  
  
  METHODS
  Data from 100 patients who underwent CRT-ICD placement were analyzed retrospectively. Patients had symptoms of New York Heart Association functional class III or IV heart failure, left ventricular ejection fraction < or =35%, and QRS duration >130 ms or QRS < or =130 ms with left intraventricular dyssynchrony. ECG indices of dispersion of repolarization before and immediately after CRT implantation (QT dispersion, Tpeak-Tend [Tp-e], and Tp-e dispersion) were measured.
  
  
  RESULTS
  In patients who were upgraded to a biventricular system, Tp-e did not increase significantly after CRT. However, Tp-e increased significantly after CRT in patients with left bundle branch block or narrow QRS at baseline. After 12-month follow-up, 22 patients had received appropriate ICD therapy. ICD therapy and no ICD therapy groups had similar baseline characteristics, such as secondary prevention and ischemic cardiomyopathy. Postimplantation Tp-e was the only independent predictor of future ICD therapy (P = .02).
  
  
  CONCLUSIONS
  Immediately after CRT, Tp-e did not increase in patients who received a biventricular upgrade; however, Tp-e did increase in patients with preimplantation left bundle branch block or narrow QRS. Postimplantation Tp-e was the only independent predictor of appropriate ICD therapy.
authors: UCLA Cardiac Arrhythmia Center, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at UCLA, University of California-Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA.
authors: Nicolas
authors: N
authors: Lellouche
authors: Carlos
authors: C
authors: De Diego
authors: Gina
authors: G
authors: Akopyan
authors: Noel G
authors: NG
authors: Boyle
authors: Aman
authors: A
authors: Mahajan
authors: David A
authors: DA
authors: Cesario
authors: Isaac
authors: I
authors: Wiener
authors: Kalyanam
authors: K
authors: Shivkumar
mesh_terms: D000328:Adult; D000368:Aged; D002037:Bundle-Branch Block / Q000628:therapy; D002303:Cardiac Output, Low / Q000628:therapy; D016757:Death, Sudden, Cardiac / Q000517:prevention & control; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000628:therapy; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012008:Recurrence; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000628:therapy; D014693:Ventricular Fibrillation / Q000628:therapy*