title: QRS duration in high-resolution methods and standard ECG in risk assessment after first and recurrent myocardial infarctions.
abstract: BACKGROUND
  Prolonged QRS duration (QRSd) is associated with increased mortality after myocardial infarction (MI). Only little data exist about its predictive ability and relationships to clinical variables in the present era of active treatment of myocardial ischemia and cardiac dysfunction. We investigated whether QRSd in high-resolution methods and standard ECG predict arrhythmic events and cardiac death in post-infarction patients with cardiac dysfunction and how it relates to clinical variables, with a special emphasis on history of previous MI.
  
  
  RESULTS
  Patients (n = 158) with acute MI and cardiac dysfunction had magnetocardiography (MCG), signal-averaged ECG (SAECG), and ECG registered at discharge. Patients with a previous MI had significantly longer QRSd although their left ventricular function was almost similarly impaired. During the mean follow-up of 50 +/- 15 (range 1-72) months, 32 patients died and 17 (53%) of the deaths were classified as cardiac. Eighteen patients had an arrhythmic event. QRSd >121 ms in MCG and >114 ms in SAECG were significant predictors of arrhythmic events and cardiac death, whereas QRSd in ECG predicted only cardiac death. In multivariate analysis, QRSd in MCG (hazard ratio (HR) = 3.6, P = 0.007) and SAECG (HR = 4.6, P = 0.016) predicted only arrhythmic events, whereas QRSd in ECG was an independent predictor of cardiac death.
  
  
  CONCLUSIONS
  Prolonged QRSd in MCG and SAECG are powerful indicators of the arrhythmia substrate in post-infarction patients with cardiac dysfunction, whereas prolonged QRSd in standard ECG associates with increased risk of cardiac death.
authors.affiliation: Division of Cardiology, Helsinki University central Hospital, Helsinki, Finland. petri.korhonen@hus.fi
authors.forename: Petri
authors.initials: P
authors.lastname: Korhonen
authors.forename: Terhi
authors.initials: T
authors.lastname: Husa
authors.forename: Ilkka
authors.initials: I
authors.lastname: Tierala
authors.forename: Heikki
authors.initials: H
authors.lastname: Väänänen
authors.forename: Markku
authors.initials: M
authors.lastname: Mäkijärvi
authors.forename: Toivo
authors.initials: T
authors.lastname: Katila
authors.forename: Lauri
authors.initials: L
authors.lastname: Toivonen
mesh_terms: D000465:Algorithms; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005387:Finland / Q000453:epidemiology; D006339:Heart Rate; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000401:mortality*; D017063:Outcome Assessment, Health Care / Q000379:methods; D011379:Prognosis; D012008:Recurrence; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D015996:Survival Rate