title: Intraventricular conduction delay in a standard 12-lead electrocardiogram as a predictor of mortality in the general population.
abstract: BACKGROUND
  Prolonged duration of QRS complex in a 12-lead ECG is associated with adverse prognosis in patients with cardiac disease, but its significance is not well established in the general population. In particular, there is a paucity of data on the prognostic significance of nonspecific intraventricular conduction delay in apparently healthy subjects.
  
  
  RESULTS
  We evaluated the 12-lead ECGs of 10 899 Finnish middle-aged subjects from the general population (52% of whom were men; mean age 44±8.5 years) between 1966 and 1972 and followed them for 30±11 years. Primary end points were all-cause mortality, cardiac mortality, and arrhythmic death. Prolonged QRS duration was defined as QRS ≥110 ms and intraventricular conduction delay as QRS ≥110 ms, without the criteria of complete or incomplete bundle-branch block. QRS duration ≥110 ms was present in 1.3% (n=147) and intraventricular conduction delay in 0.6% (n=67) of the subjects. Prolonged QRS duration predicted all-cause mortality (multivariate-adjusted relative risk [RR] 1.48; 95% confidence interval [CI] 1.22-1.81; P<0.001), cardiac mortality (RR 1.94; CI 1.44-2.63; P<0.001), and sudden arrhythmic death (RR 2.14; CI 1.38-3.33; P=0.002). Subjects with intraventricular conduction delay had increased all-cause mortality (RR 2.01; CI 1.52-2.66; P<0.001), increased cardiac mortality (RR 2.53; CI 1.64-3.90; P<0.001), and an elevated risk of arrhythmic death (RR 3.11; CI 1.74-5.54; P=0.001). Left bundle-branch block also weakly predicted arrhythmic death (P=0.04), but right bundle-branch block was not associated with increased mortality.
  
  
  CONCLUSIONS
  Prolonged QRS duration in a standard 12-lead ECG is associated with increased mortality in a general population, with intraventricular conduction delay being most strongly associated with an increased risk of arrhythmic death.
authors.affiliation: Division of Cardiology, Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland. aapo.aro@helsinki.fi
authors.forename: Aapo L
authors.initials: AL
authors.lastname: Aro
authors.forename: Olli
authors.initials: O
authors.lastname: Anttonen
authors.forename: Jani T
authors.initials: JT
authors.lastname: Tikkanen
authors.forename: M Juhani
authors.initials: MJ
authors.lastname: Junttila
authors.forename: Tuomas
authors.initials: T
authors.lastname: Kerola
authors.forename: Harri A
authors.initials: HA
authors.lastname: Rissanen
authors.forename: Antti
authors.initials: A
authors.lastname: Reunanen
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000453:epidemiology / Q000401:mortality*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000502:physiology*; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors