title: QRS-T angle as a predictor of sudden cardiac death in a middle-aged general population.
abstract: OBJECTIVE
  Spatial QRS-T angle measured from a 12-lead electrocardiogram (ECG) has been shown to predict cardiac mortality. However, there is a paucity of studies on the prognostic significance of frontal QRS-T angle, which is more readily available from the standard 12-lead ECG. The purpose of the present study was to investigate the importance of wide frontal QRS-T angle, QRS-axis, and T-wave axis as cardiac risk predictors in general population.
  
  
  RESULTS
  We evaluated the 12-lead ECGs of 10 957 Finnish middle-aged subjects from the general population recorded between 1966 and 1972, and followed them for 30 ± 11 years. QRS-T angle 0 to 90°, QRS-axis -30 to 90°, and T-wave axis 0 to 90° were considered normal. The primary endpoint was death from arrhythmia, and the secondary endpoints were all-cause mortality and non-arrhythmic cardiac mortality. QRS-T angle ≥ 100° was present in 2.0% of the subjects, and it was associated with an increased risk of sudden arrhythmic death [relative risk (RR) 2.26; 95% confidence interval (CI) 1.59-3.21; P< 0.001) and all-cause mortality (RR 1.57; CI 1.34-1.84; P< 0.001), but not with non-arrhythmic cardiac mortality (RR 1.34; CI 0.93-1.92; P= 0.13). The prognostic significance of wide QRS-T angle was mainly due to abnormal T-wave axis, which predicted death from arrhythmia (RR 2.13; CI 1.63-2.79; P< 0.001), all-cause mortality (RR 1.39; 1.24-1.55; P< 0.001), and non-arrhythmic cardiac death (RR 1.87; CI 1.50-2.34; P< 0.001).
  
  
  CONCLUSIONS
  Frontal QRS-T angle ≥ 100° increases the risk of arrhythmic death, this being mainly the result of an altered T-wave axis.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Helsinki University Central Hospital, Helsinki, Finland. aapo.aro@helsinki.fi
authors.forename: Aapo L
authors.initials: AL
authors.lastname: Aro
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
authors.forename: Jani T
authors.initials: JT
authors.lastname: Tikkanen
authors.forename: M Juhani
authors.initials: MJ
authors.lastname: Junttila
authors.forename: Harri A
authors.initials: HA
authors.lastname: Rissanen
authors.forename: Antti
authors.initials: A
authors.lastname: Reunanen
authors.forename: Olli
authors.initials: O
authors.lastname: Anttonen
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000401:mortality*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis / Q000401:mortality; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009313:National Health Programs / Q000706:statistics & numerical data; D011237:Predictive Value of Tests; D012307:Risk Factors