title: QRS pattern and improvement in right and left ventricular function after cardiac resynchronization therapy: a radionuclide study.
abstract: BACKGROUND
  Predicting response to cardiac resynchronization therapy (CRT) remains a challenge. We evaluated the role of baseline QRS pattern to predict response in terms of improvement in biventricular ejection fraction (EF).
  
  
  METHODS
  Consecutive patients (pts) undergoing CRT implantation underwent radionuclide angiography at baseline and at mid-term follow-up. The relationship between baseline QRS pattern and mechanical dyssynchrony using phase analysis was evaluated. Changes in left and right ventricular EF (LVEF and RVEF) were analyzed with regard to baseline QRS pattern.
  
  
  RESULTS
  We enrolled 56 pts, 32 with left bundle branch block (LBBB), 4 with right bundle branch block (RBBB) and 20 with non-specific intraventricular conduction disturbance (IVCD). A total of 48 pts completed follow-up. LBBB pts had significantly greater improvement in LVEF compared to RBBB or non-specific IVCD pts (+9.6 ± 10.9% vs. +2.6 ± 7.6%, p = 0.003). Response (defined as ≥ 5% increase in LVEF) was observed in 68% of LBBB vs. 24% of non-specific IVCD pts (p = 0.006). None of the RBBB pts were responders. RVEF was significantly improved in LBBB (+5.0 ± 9.0%, p = 0.007), but not in non-specific IVCD and RBBB pts (+0.4 ± 5.8%, p = 0.76). At multivariate analysis, LBBB was the only predictor of LVEF response (OR, 7.45; 95% CI 1.80-30.94; p = 0.006), but not QRS duration or extent of mechanical dyssynchrony.
  
  
  CONCLUSIONS
  Presence of a LBBB is a marker of a positive response to CRT in terms of biventricular improvement. Pts with non-LBBB pattern show significantly less benefit from CRT than those with LBBB.
authors.affiliation: Institute of Cardiology, University of Bologna, Via Massarenti 9, Bologna 40138, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Domenichini
authors.forename: Haran
authors.initials: H
authors.lastname: Burri
authors.forename: Cinzia
authors.initials: C
authors.lastname: Valzania
authors.forename: Gilberto
authors.initials: G
authors.lastname: Gavaruzzi
authors.forename: Francesco
authors.initials: F
authors.lastname: Fallani
authors.forename: Mauro
authors.initials: M
authors.lastname: Biffi
authors.forename: Henri
authors.initials: H
authors.lastname: Sunthorn
authors.forename: Igor
authors.initials: I
authors.lastname: Diemberger
authors.forename: Cristian
authors.initials: C
authors.lastname: Martignani
authors.forename: Huberdine
authors.initials: H
authors.lastname: Foulkes
authors.forename: Eric
authors.initials: E
authors.lastname: Fleury
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Boriani
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000628:therapy*; D002037:Bundle-Branch Block / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011875:Radionuclide Angiography; D013318:Stroke Volume / Q000502:physiology*; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000502:physiology*; D016278:Ventricular Function, Right / Q000502:physiology*