title: Asymptomatic Left Bundle Branch Block Predicts New-Onset Congestive Heart Failure and Death From Cardiovascular Diseases.
abstract: BACKGROUND
  Left bundle branch block (LBBB) has been proposed as a risk factor for cardiovascular morbidity and mortality. We sought to characterize the strength of these associations in a population without preexisting clinical heart disease.
  
  
  METHODS
  The association between LBBB and new-onset congestive heart failure (CHF) or death from cardiovascular diseases was examined in 1,688 participants enrolled in the SPPARCS study who were free of known CHF or previous myocardial infarction. SPPARCS is a community-based cohort study in residents of Sonoma, California that are > 55 years. Medical history and 12-lead ECGs were obtained every 2 years for up to 6 years of follow-up. LBBB at enrollment or year 2 was considered "baseline" and assessed as a predictor of CHF and cardiovascular death ascertained at years 4 and 6.
  
  
  RESULTS
  The prevalence of LBBB at baseline was 2.5% (n = 42). During 6 years of follow-up, 70 (4.8%) people developed new CHF. Incidence of CHF was higher in patients with LBBB than in participants without LBBB. This association persisted after controlling for potential confounders (odds ratio (OR): 2.85; 95% confidence interval (CI): 1.01 - 8.02; P = 0.047). A higher mortality from cardiovascular diseases was also found in participants with LBBB after adjusting for potential confounders (OR: 2.35, 95%CI: 1.02 - 5.41; P = 0.044).
  
  
  CONCLUSIONS
  LBBB in the absence of a clinically detectable heart disease is associated with new-onset CHF and death from cardiovascular diseases. Further study is warranted to determine if additional diagnostic testing or earlier treatment in patients with asymptomatic LBBB can decrease cardiovascular morbidity or mortality.
authors.affiliation: Penn State Hershey Medical Center, PA, USA.
authors.forename: Peyman N
authors.initials: PN
authors.lastname: Azadani
authors.affiliation: University of California, San Francisco, School of Medicine, San Francisco, CA, USA.
authors.forename: Ata
authors.initials: A
authors.lastname: Soleimanirahbar
authors.affiliation: University of California, San Francisco, School of Medicine, San Francisco, CA, USA.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Marcus
authors.affiliation: University of California, Berkeley, School of Public Health, Berkeley, CA, USA.
authors.forename: Thaddeus J
authors.initials: TJ
authors.lastname: Haight
authors.affiliation: University of California, San Francisco, School of Medicine, San Francisco, CA, USA.
authors.forename: Milton
authors.initials: M
authors.lastname: Hollenberg
authors.affiliation: University of California, San Francisco, School of Medicine, San Francisco, CA, USA.
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Olgin
authors.affiliation: University of California, San Francisco, School of Medicine, San Francisco, CA, USA.
authors.forename: Byron K
authors.initials: BK
authors.lastname: Lee
keywords: Bundle-branch block; Heart failure; Mortality; Risk factors