title: Ventricular tachycardia or ventricular fibrillation occurs less often in patients with left bundle branch block and combined resynchronization and defibrillators than in patients with narrow QRS and conventional defibrillators.
abstract: OBJECTIVE
  Mortality in chronic heart failure (CHF) patients with left bundle branch block (LBBB) is high. Cardiac resynchronization therapy (CRT) reduces symptoms and mortality in CHF patients with LBBB. Whether CRT promotes or prevents ventricular tachycardia (VT)/ventricular fibrillation (VF) remains controversial, however. Therefore, we aimed to analyse arrhythmia-related CRT effects and characterized the VT/VF incidence in CRT-defibrillator patients and matched controls with conventional implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden cardiac death.
  
  
  RESULTS
  We enrolled 134 patients [110 men, left ventricular ejection fraction (LVEF) 24 ± 8%, 71 coronary artery disease, CRT-ICD 67, conventional ICD matched controls 67, follow-up 31 ± 17 months] and monitored overall survival and the time to a first VT/VF episode. Controls did not have LBBB. They were otherwise matched for age, LVEF, and follow-up duration. Gender and underlying disease did not differ between the groups. Kaplan-Meier analysis revealed more favourable arrhythmia-free survival in CRT-ICD vs. conventional ICD patients [hazard ratio (HR) 2.26, confidence interval (CI) 1.09-4.67, log rank P = 0.023]. The difference persisted in the multivariate Cox regression analysis (HR 3.25, CI 1.18-8.93, P= 0.022). Overall survival was similar in both groups (HR 1.45, CI 0.55-3.82, P = 0.45).
  
  
  CONCLUSIONS
  Chronic heart failure patients with LBBB treated with CRT-ICD, experience less and delayed VT/VF episodes compared with matched controls without LBBB receiving conventional ICD. In the long-term, CRT appears to exert antiarrhythmic effects and to attenuate the particularly high arrhythmia-related risk of CHF patients with LBBB. The incremental benefit of adding the ICD option to CRT pacing in LBBB patients appears questionable.
authors.affiliation: Charité-Universitaetsmedizin Berlin, Campus Virchow-Klinikum, Medizinische Klinik mit Schwerpunkt Kardiologie, Augustenburger Platz 1, 13353 Berlin, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Blaschke
authors.forename: Thomas
authors.initials: T
authors.lastname: Knaus
authors.forename: Oezlem
authors.initials: O
authors.lastname: Celebi
authors.forename: Alice
authors.initials: A
authors.lastname: Krebs
authors.forename: Aischa
authors.initials: A
authors.lastname: Nitardy
authors.forename: Dirk
authors.initials: D
authors.lastname: Habedank
authors.forename: Rainer
authors.initials: R
authors.lastname: Dietz
authors.forename: Martin
authors.initials: M
authors.lastname: Stockburger
mesh_terms: D002037:Bundle-Branch Block / Q000401:mortality / Q000517:prevention & control*; D058406:Cardiac Resynchronization Therapy / Q000706:statistics & numerical data*; D016022:Case-Control Studies; D003131:Combined Modality Therapy / Q000706:statistics & numerical data; D015897:Comorbidity; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D018572:Disease-Free Survival; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D018570:Risk Assessment; D012307:Risk Factors; D016019:Survival Analysis; D015996:Survival Rate; D017180:Tachycardia, Ventricular / Q000401:mortality / Q000517:prevention & control*; D014693:Ventricular Fibrillation / Q000401:mortality / Q000517:prevention & control*