title: Delayed QRS transition in the precordial leads of an electrocardiogram as a predictor of sudden cardiac death in the general population.
abstract: BACKGROUND
  QRS transition zone is related to the electrical axis of the heart in the horizontal plane and is easily determined from the precordial leads of a standard 12-lead ECG. However, whether delayed QRS transition, or clockwise rotation of the heart, carries prognostic implications and predicts sudden cardiac death (SCD) is unclear.
  
  
  OBJECTIVE
  The purpose of this study was to study whether delayed transition is associated with mortality and SCD.
  
  
  METHODS
  We evaluated 12-lead ECGs of 10,815 Finnish middle-aged subjects from the general population (52% men, mean age 44 ± 8.5 years) and followed them for 30 ± 11 years. Main end-points were mortality and SCD.
  
  
  RESULTS
  Delayed QRS transition at lead V4 or later occurred in 1770 subjects (16.4%) and markedly delayed transition at lead V5 or later in 146 subjects (1.3%). Delayed transition zone was associated with older age, male gender, higher body mass index, hypertension, baseline cardiovascular disease, leftward shift of the frontal QRS axis, wider QRS-T angle, and ECG left ventricular hypertrophy. After adjusting for several clinical and ECG variables, delayed transition was associated with overall mortality (hazard ratio [HR] 1.15, 95% confidence interval [CI] 1.07-1.22, P < .001) and SCD (HR 1.23, 95% CI 1.03-1.47, P = .029). Markedly delayed transition at V5 or later predicted significantly SCD (HR 1.89, 95% CI 1.18-3.03, P = .008) and all-cause mortality (HR 1.30, 95% CI 1.07-1.58, P = .01). However, further adjustments for repolarization abnormalities attenuated this effect.
  
  
  CONCLUSIONS
  Delayed QRS transition in the precordial leads of an ECG seems to be a novel ECG risk marker for SCD. In particular, markedly delayed transition was associated with significantly increased risk of SCD, independent of confounding factors.
authors.affiliation: Division of Cardiology, Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland. Electronic address: aapo.aro@helsinki.fi.
authors.forename: Aapo L
authors.initials: AL
authors.lastname: Aro
authors.affiliation: Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Eranti
authors.affiliation: Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Anttonen
authors.affiliation: Department of Internal Medicine, Päijät-Häme Central Hospital, Lahti, Finland.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Kerola
authors.affiliation: National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Harri A
authors.initials: HA
authors.lastname: Rissanen
authors.affiliation: National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Paul
authors.initials: P
authors.lastname: Knekt
authors.affiliation: Division of Cardiology, Heart and Lung Center, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Kimmo
authors.initials: K
authors.lastname: Porthan
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.
authors.forename: Jani T
authors.initials: JT
authors.lastname: Tikkanen
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.
authors.forename: M Juhani
authors.initials: MJ
authors.lastname: Junttila
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
mesh_terms: D000328:Adult; D017677:Age Distribution; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000401:mortality*; D002423:Cause of Death; D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D017678:Sex Distribution; D013997:Time Factors
keywords: Clockwise rotation; Electrocardiography; Population; QRS transition; Sudden cardiac death