title: True complete left bundle branch block morphology strongly predicts good response to cardiac resynchronization therapy.
abstract: OBJECTIVE
  To determine whether patients with congestive heart failure and true left bundle branch block (LBBB) morphology have better response to cardiac resynchronization therapy (CRT) than do patients without true LBBB.
  
  
  RESULTS
  We defined true LBBB as conventional LBBB plus QRS duration ≥ 130 ms and mid-QRS notching/slurring in at least two of the leads I, aVL, V1, V2, V5, or V6. We prospectively enrolled 58 patients with heart failure and allocated them to three groups: true LBBB (t-LBBB, n = 22); non-true LBBB (nt-LBBB, LBBB with no notch or notches in fewer than two of the leads, n = 17); and non-specific intraventricular conduction delay (IVCD, n = 19). At 6 month follow-up, mean absolute increases in left ventricular ejection fraction were 16.0% ± 11.6% in t-LBBB, 8.1% ± 11.2% in nt-LBBB (P = 0.02), and 3.3% ± 7.8% in IVCD (P < 0.001, t-LBBB vs. IVCD) and changes in mean New York Heart Association class were -1.2 ± 0.6 in t-LBBB, -0.8 ± 0.6 in nt-LBBB (P = 0.071), and -0.5 ± 0.6 in IVCD (P = 0.01, t-LBBB vs. IVCD). All patients with t-LBBB were responders, some were super-responders. Multivariate analysis showed that t-LBBB (odds ratio, OR, 11.680; 95% confidence interval, CI, 1.966-69.390; P = 0.007) and left ventricular end-diastolic dimension (OR, 0.891; 95% CI, 0.797-0.996; P = 0.043) are independent predictors of super-response to CRT.
  
  
  CONCLUSIONS
  In patients with conventional wider LBBB morphology, the presence of mid-QRS notching or slurring is a strong predictor of better response to CRT.
authors.affiliation: Department of Cardiac Electrophysiology, People's Hospital, Peking University, 100044 Beijing, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Tian
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.forename: Xuebin
authors.initials: X
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Gao
authors.forename: Tiangang
authors.initials: T
authors.lastname: Zhu
authors.forename: Long
authors.initials: L
authors.lastname: Wang
authors.forename: Ding
authors.initials: D
authors.lastname: Li
authors.forename: Jiayu
authors.initials: J
authors.lastname: Wang
authors.forename: Cuizhen
authors.initials: C
authors.lastname: Yuan
authors.forename: Jihong
authors.initials: J
authors.lastname: Guo
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy; D004562:Electrocardiography; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D018579:Patient Selection; D011446:Prospective Studies; D020127:Recovery of Function; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left
keywords: Cardiac resynchronization therapy; Electrocardiology; Heart failure; Left bundle branch block; Response