title: The prevalence and incidence of left bundle branch block in ambulant patients with chronic heart failure.
abstract: BACKGROUND
  Approximately one third of patients with chronic heart failure have left bundle branch block (LBBB) on their 12-lead ECG.
  
  
  RESULTS
  1418 consecutive patients (average (SD) age 70.5 (10.4) years; 74% male) first seen in a community heart failure clinic between December 2001 and June 2006 had a 12 lead electrocardiogram (ECG). 485 (34%) had a QRS duration >or=120 ms. Patients with a broad QRS were older (72.2 v 69.3 years), had worse left ventricular systolic function, were on a higher daily dose of diuretic and were more likely to be on amiodarone (14.4 v 7.1%). 12 lead ECG was available for 734 patients (52%) at 1 year follow up. The QRS interval increased from 115.1 ms at baseline to 117.6 (P<0.0001). There were 52 incident cases of LBBB, an incidence of 10.9%. The only predictors of incident LBBB were QRS duration at baseline and amiodarone use at baseline. The proportion of patients with LBBB increased from 34.0% at baseline to 36.7%, 37.7% and 42.3% at 1, 2 and 3 years follow up, respectively. Baseline LBBB was associated with a worse outcome (HR 1.25 (95% CI 1.01-1.55). New LBBB was an independent adverse prognostic feature (HR 2.09 (95% CI 1.17-3.73); P=0.013).
  
  
  CONCLUSIONS
  The crude incidence of LBBB is 10.9% in the first year of follow up in an unselected population of ambulatory outpatients with chronic stable heart failure. Ongoing care of patients with chronic heart failure should include a regular 12 lead electrocardiogram.
authors.affiliation: Department of Academic Cardiology, Castle Hill Hospital, Castle Road, Cottingham, Hull, UK. HU16 5JQ, UK. a.l.clark@hull.ac.uk
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Clark
authors.forename: Kevin
authors.initials: K
authors.lastname: Goode
authors.forename: John G F
authors.initials: JG
authors.lastname: Cleland
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology; D016009:Chi-Square Distribution; D002908:Chronic Disease; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology; D006801:Humans; D015994:Incidence; D008297:Male; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D018709:Statistics, Nonparametric; D006113:United Kingdom / Q000453:epidemiology