title: A left hemiblock improves cardiac resynchronization therapy outcomes in patients with a right bundle branch block.
abstract: BACKGROUND
  The current recommendation for cardiac resynchronization therapy (CRT) in congestive heart failure (CHF) patients is based on QRS duration, not on QRS morphology.
  
  
  OBJECTIVE
  This study was performed to compare the effects of CRT in CHF patients with pure RBBB vs those with a coexisting left hemiblock (LHB). METHODS AND PATIENT POPULATION: A total of 271 consecutive patients who underwent CRT at Montefiore Medical Center were analyzed. Baseline ECGs were analyzed by 2 reviewers for RBBB and further classified into those with a coexisting LHB. Response to CRT was defined to be, at > or = 6 months after CRT, either an improvement in ejection fraction (EF) of at least 5%, or an improvement in New York Heart Association (NYHA) CHF class. A total of 44 patients were identified: 18 had pure RBBB and 26 had a coexisting LHB. The 2 groups were similar in respect to baseline characteristics (P > 0.05).
  
  
  RESULTS
  Only 4 out of 18 patients with pure RBBB compared to 18 out of 26 with LHB (P = 0.005) had an improvement in EF > or = 5%. The mean EF was - 1% in the pure RBBB group, but + 5.4% in those with LHB (P = 0.0031). Improvement in NYHA class was seen in 0 out of 18 with pure RBBB vs 7 out of 26 patients with LHB (P = 0.03).
  
  
  CONCLUSIONS
  If patients with RBBB also had LHB, their response to CRT was significantly better than if they had RBBB alone.
authors.affiliation: Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, New York 10461, USA.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Chandra
authors.forename: Ronald
authors.initials: R
authors.lastname: Zolty
authors.forename: Eugen
authors.initials: E
authors.lastname: Palma
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D016009:Chi-Square Distribution; D004562:Electrocardiography; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D020127:Recovery of Function; D012189:Retrospective Studies; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left