title: The emergency department electrocardiogram and hospital complications in myocardial infarction patients.
abstract: OBJECTIVE
  To determine whether acute myocardial infarction (AMI) patients who have negative ECGs on presentation have significantly lower complication rates than do those AMI patients who have positive ECGs on presentation.
  
  
  METHODS
  Retrospective, cohort analysis comparing rates of hospital complications (ventricular fibrillation or tachycardia, shock, atrial arrhythmia or bradyarrhythmia with systolic blood pressure < or = 90 mm Hg, pulmonary edema) or interventions among patients with a final hospital diagnosis of AMI and an initially negative vs positive ECG. A negative ECG was normal or had nonspecific ST-segment and/or T-wave abnormalities (upright, flattened T waves; an isolated inverted T wave; ST depression < 0.1 mV; tall T waves with J-point elevation) or minor nonischemic abnormalities. Sample size was adequate to detect a 30% between-group difference in complication rates [alpha = 0.05, 1 - beta (power) = 0.80].
  
  
  RESULTS
  The 27 negative-ECG AMI patients differed from the 38 control patients in (mean +/- SD) age [57 +/- 12 vs 66 +/- 12 years, p < 0.01] but not in gender or history of AMI. The negative- and positive-ECG groups had similar rates of hospital complications [30% (95% CI: 13-47%) vs 42% (95% CI: 26-58%), p = 0.44] and intensive procedures [19% (95% CI: 4-34%) vs 29% (95% CI: 15-43%), p = 0.50], respectively. The negative-ECG patients with hospital complications had ECG evolution precede the event in 83% (95% CI: 69-97%) of cases; persistently negative-ECG patients had no complications [(95% CI: 0-33%), p = 0.06].
  
  
  CONCLUSIONS
  Negative- and positive-ECG AMI patients do not have moderate or large differences in the rates of in-hospital complications. Most negative-ECG patients who suffer complications evolve ECG changes prior to the event and such changes indicate the potential need for a higher level of care.
authors.affiliation: Center for Health Services Research, University of Illinois at Chicago 60612-7260, USA. u48729@uicvm.uic.edu
authors.forename: R J
authors.initials: RJ
authors.lastname: Zalenski
authors.forename: R J
authors.initials: RJ
authors.lastname: Rydman
authors.forename: E P
authors.initials: EP
authors.lastname: Sloan
authors.forename: L
authors.initials: L
authors.lastname: Caceres
authors.forename: D G
authors.initials: DG
authors.lastname: Murphy
authors.forename: D
authors.initials: D
authors.lastname: Cooke
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000704:Analysis of Variance; D015331:Cohort Studies; D016001:Confidence Intervals; D004562:Electrocardiography; D004632:Emergency Medical Services / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D017678:Sex Distribution; D015996:Survival Rate