title: Predicting Ventricular Arrhythmias in Cardiac Resynchronization Therapy: The Impact of Persistent Electrical Dyssynchrony.
abstract: BACKGROUND
  Although response to cardiac resynchronization therapy (CRT) has been conventionally assessed with left ventricular volume reduction, ventricular arrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) are of critical importance associated with unfavorable outcomes even in the "superresponders" to therapy. We evaluated the predictors of VT/VF and the association of residual dyssynchrony during follow-up.
  
  
  METHODS
  Ninety-five patients receiving CRT were followed-up for 9 ± 3 months. Post-CRT dyssynchrony was defined as a prolonged QRS duration (QRSd) for persistent electrical dyssynchrony (ED), and a Yu index ≥ 33 ms for persistent mechanical dyssynchrony. The first VT/VF episode, including nonsustained VT detected on device interrogation and/or appropriate antitachycardia pacing or shock for VT/VF, were the end points of the study.
  
  
  RESULTS
  Forty-five patients who reached the study end points had significantly lower mean ΔQRS (baseline QRSd - post-CRT QRSd) values than those without VT/VF (-20.8 ± 28.9 ms vs -6.6 ± 30.7 ms, P = 0.022). Both the baseline and post-CRT QRSds, along with the Yu index values, were not different in two groups. Patients with VT/VF were statistically more likely to have persistent ED (38% vs 9%, P = 0.021). Kaplan-Meier curves showed that a negative ΔQRS was associated with a higher incidence of VT/VF during follow-up (P = 0.016). A multivariate Cox model revealed that QRS prolongation was an independent predictor of VT/VF after CRT (P = 0.029).
  
  
  CONCLUSIONS
  A negative ΔQRS, also called persistent ED, is associated with VT/VF. Narrowest possible QRSd might be a reliable goal of both implantation and optimization of devices to reduce arrhythmic events after CRT.
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey. oguzkaraca@hotmail.com.
authors.forename: Oguz
authors.initials: O
authors.lastname: Karaca
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Haci M
authors.initials: HM
authors.lastname: Gunes
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Mehmet Onur
authors.initials: MO
authors.lastname: Omaygenc
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Beytullah
authors.initials: B
authors.lastname: Cakal
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Sinem Deniz
authors.initials: SD
authors.lastname: Cakal
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Gultekin Gunhan
authors.initials: GG
authors.lastname: Demir
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Filiz
authors.initials: F
authors.lastname: Kizilirmak
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Tayyar
authors.initials: T
authors.lastname: Gokdeniz
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Irfan
authors.initials: I
authors.lastname: Barutcu
authors.affiliation: Cardiology Department, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Bilal
authors.initials: B
authors.lastname: Boztosun
authors.affiliation: Cardiac Electrophysiology, Medipol University Faculty of Medicine, Istanbul, Turkey.
authors.forename: Fethi
authors.initials: F
authors.lastname: Kilicaslan
mesh_terms: D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods; D011379:Prognosis; D012008:Recurrence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000628:therapy*; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000628:therapy*
keywords: QRS duration; cardiac resynchronization therapy; electrical dyssynchrony; mechanical dyssynchrony; ventricular arrhythmia