title: Does 24-hour ST-segment resolution postfibrinolysis add prognostic value to a Q wave? An ASSENT 2 electrocardiographic substudy.
abstract: BACKGROUND
  Both ST resolution and Q-wave development postfibrinolysis provide important prognostic insights in patients with acute myocardial infarction (MI). However, the relative contributions of these 2 factors to risk assessment have not been examined prospectively.
  
  
  RESULTS
  ST resolution and Q development were evaluated 24 to 36 hours (24-36 h) postfibrinolysis in ASSENT-2: 13,100 out of 16,949 patients who had both baseline and 24-36 h electrocardiograms free of confounders (left bundle branch block, ventricular rhythm, reinfarction before 24-36 h electrocardiograms) were included in this analysis. Q-wave MI evolved in 10,466 patients (79.9%) and 2634 patients (20.1%) had non-Q-wave MI at 24-36 h postfibrinolysis. Mortality rates at 1-year were 7.0% for patients with Q-wave MI and 5.8% for non-Q-wave MI patients, respectively (P =.046). Patients with Q-wave MI versus those without were less likely to have complete ST-segment resolution (49.1% vs 59.1%) and more likely to have partial (37.1% vs 27.8%) or no resolution (13.8% vs 13.1%) at 24 to 36 hours postfibrinolysis (P <.001). Mortality rates at 1 year for Q-wave MI with complete, partial, and no resolution were 5.2%, 8.1%, and 10.1%, respectively (P <.001), and for non-Q-wave MI with complete, partial, and no resolution were 4.5%, 7.6%, and 8.0% (P =.003).
  
  
  CONCLUSIONS
  These results demonstrate the additional prognostic significance of ST-segment resolution to Q-wave development at 24 to 36 hours after fibrinolysis.
authors.affiliation: University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Evan
authors.initials: E
authors.lastname: Lockwood
authors.forename: Yuling
authors.initials: Y
authors.lastname: Fu
authors.forename: Brian
authors.initials: B
authors.lastname: Wong
authors.forename: Frans
authors.initials: F
authors.lastname: Van de Werf
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Granger
authors.forename: Paul W
authors.initials: PW
authors.lastname: Armstrong
authors.forename: Shaun G
authors.initials: SG
authors.lastname: Goodman
mesh_terms: D000368:Aged; D004311:Double-Blind Method; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000503:physiopathology*; D011379:Prognosis; D011446:Prospective Studies; D013223:Statistics as Topic; D015912:Thrombolytic Therapy; D013997:Time Factors