title: Prognostic significance of bundle-branch block in acute myocardial infarction: the importance of location and time of appearance.
abstract: BACKGROUND
  The presence of bundle-branch block (BBB) is associated with high mortality rates and is considered an important predictor of poor outcome in patients with acute myocardial infarction (AMI).
  
  
  OBJECTIVE
  The objective of this study was to assess the prognostic significance of BBB in patients with AMI depending on its form of presentation.
  
  
  METHODS
  A multicenter prospective 1-year follow-up study involving 1,239 consecutive patients diagnosed with AMI was performed.
  
  
  RESULTS
  Bundle-branch block was present in 177 cases (14.2%), associated with worse clinical characteristics, lower rate of thrombolytic therapy, and higher mortality: in-hospital (23.8 vs. 9.7%, p < .01) and 1-year (40.9 vs. 16.9%, p < 0.01). Compared with right BBB (n = 135), left BBB (n = 42) was more often associated with female gender and higher prevalence of cardiovascular diseases, but had a similar 1-year mortality. In the absence of heart failure or complete atrioventricular (AV) block, there was no difference in in-hospital mortality of patients with BBB (n = 76) and without BBB (n = 786) (2.6 vs. 3.9%). Compared with existing BBB (n = 113), BBB of new appearance (n = 64) was more often accompanied by complete AV block and heart failure and higher in-hospital and 1-year mortality rates. Only BBB of new appearance was an independent predictor of mortality: in-hospital (odds ratio [OR] 2.3, 95% confidence interval [CI] 1.1-4.7) and 1-year mortality (OR 3.2, 95% CI, 1.7-9.1).
  
  
  CONCLUSIONS
  In patients with AMI, the classification of BBB according not only to location but also to time of appearance is of practical interest. New BBB is an independent predictor of short- and long-term mortality.
authors.affiliation: Hospital Santa Maria del Rosell de Cartagena, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Melgarejo-Moreno
authors.forename: J
authors.initials: J
authors.lastname: Galcerá-Tomás
authors.forename: A
authors.initials: A
authors.lastname: Garcia-Alberola
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000150:complications* / Q000401:mortality; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications*; D011379:Prognosis; D011446:Prospective Studies