title: Concordant versus discordant left bundle branch block in heart failure patients: novel clinical value of an old electrocardiographic diagnosis.
abstract: BACKGROUND
  Over the last 50 years left bundle branch block (LBBB) has been defined as homophasic (concordant: cLBBB) or heterophasic (discordant: dLBBB) when associated with a positive or negative T wave in leads I and V5-V6, respectively. LBBB is recognized as an adverse prognostic factor in heart failure (HF). The prevalence and clinical significance of cLBBB and dLBBB in HF patients are unknown.
  
  
  RESULTS
  A total of 897 consecutive systolic HF patients (age 65 +/- 13 years, left ventricular ejection fraction [LVEF], 34 +/- 10%) underwent clinical characterization, electrocardiographic evaluation for LBBB diagnosis and classification, and follow-up for cardiac events (median 37 months, range 1-84). LBBB was diagnosed in 232 patients (26%), cLBBB in 71 (31%), and dLBBB in 161 (69%). The dLBBB patients were older than those with cLBBB, and presented with lower LVEF, greater left ventricular telediastolic diameter and left ventricular mass index, higher level of brain natriuretic peptide, N-terminal pro-brain natriuretic peptide, renin activity, and norepinephrine (all P < .05). At Kaplan-Meier analysis, LBBB (P = .003) and dLBBB (P = .036) were associated with a worse prognosis when the composite end point of sudden death and implantable cardioverter defibrillator shock was considered.
  
  
  CONCLUSIONS
  In systolic HF, dLBBB is associated with a worse clinical, neurohormonal, and prognostic profile. LBBB classification could represent a useful tool in routine clinical evaluation.
authors.affiliation: Postgraduate School of Cardiology, University of Florence, Florence, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Padeletti
authors.forename: Alessandro
authors.initials: A
authors.lastname: Valleggi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vergaro
authors.forename: Fabiana
authors.initials: F
authors.lastname: Lucà
authors.forename: Carmelo M
authors.initials: CM
authors.lastname: Rao
authors.forename: Laura
authors.initials: L
authors.lastname: Perrotta
authors.forename: Francesco
authors.initials: F
authors.lastname: Cappelli
authors.forename: Antonio
authors.initials: A
authors.lastname: L'Abbate
authors.forename: Claudio
authors.initials: C
authors.lastname: Passino
authors.forename: Michele
authors.initials: M
authors.lastname: Emdin
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015996:Survival Rate / Q000639:trends