title: Relationship between electrocardiographic characteristics of left bundle branch block and echocardiographic findings.
abstract: BACKGROUND
  Complete left bundle branch block (CLBBB) is an electrocardiographic (ECG) dromotropic disorder seen in patients with various structural heart diseases and sometimes is associated with poor prognosis. Its presence confounds the application of standard ECG criteria for the diagnosis of left ventricular hypertrophy (LVH), myocardial infarction (MI) in the chronic phase, and pathologies that produce changes on ST-T segment. The aim of this investigation was to establish the relationship between CLBBB and cardiac structural abnormalities assessed by echocardiography.
  
  
  METHODS
  This observational, cross-sectional study included ECG with CLBBB from 101 patients who also had transthoracic echocardiogram (TTE) performed within 6 months.
  
  
  RESULTS
  The prevalence of structural heart disease on TTE was 90%. No ECG criterion was useful to diagnose LVH since no relationship was observed between 9 different ECG signs and increased left ventricular mass index. QRS duration (p = 0.16) and left axis deviation (p = 0.09) were unrelated to reduced left ventricular ejection fraction (LVEF). Eight ECG signs proposed for the diagnosis of the chronic phase of MI demonstrated similar effectiveness, with high specificity and reduced sensitivity.
  
  
  CONCLUSIONS
  CLBBB is associated with elevated prevalence of cardiac structural disease and hinders the application of common ECG criteria for the diagnosis of LVH, reduced LVEF, or chronic phase of MI. No ECG finding distinguished patients with structural heart disease from those with normal hearts. Electrocardiographic criteria for the diagnosis of MI in the chronic phase are useful when present, but when absent cannot rule it out.
authors.forename: Augusto J
authors.initials: AJ
authors.lastname: Lépori
authors.forename: Ricardo S
authors.initials: RS
authors.lastname: Mishima
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Rodriguez
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Moreyra
authors.forename: Jose L
authors.initials: JL
authors.lastname: Serra
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Tibaldi
authors.forename: Andres
authors.initials: A
authors.lastname: Martellotto
authors.affiliation: FACC Sanatorio Allende. eddie.moreyra@gmail.com.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Moreyra
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001118:Argentina / Q000453:epidemiology; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015995:Prevalence; D015203:Reproducibility of Results; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left