title: Diagnostic time course, treatment, and in-hospital outcomes for patients with ST-segment elevation myocardial infarction presenting with nondiagnostic initial electrocardiogram: a report from the American Heart Association Mission: Lifeline program.
abstract: BACKGROUND
  Prior studies indicate that a subset of patients diagnosed as having ST-segment elevation myocardial infarction (STEMI) will have an initial non-diagnostic electrocardiogram (ECG) during evaluation. However, the timing of diagnostic ECG changes in this group is unknown. Our primary aim was to describe the timing of ECG diagnosis of STEMI in patients whose initial ECG was non-diagnostic. Secondarily, we sought to compare the delivery of American College of Cardiology/American Heart Association guidelines-based care and in-hospital outcomes in this group compared with patients diagnosed as having STEMI on initial ECG.
  
  
  METHODS
  We analyzed data from 41,560 patients diagnosed as having STEMI included in the National Cardiovascular Data Registry ACTION Registry-GWTG from January 2007 to December 2010. We divided this study population into 2 groups: those diagnosed on initial ECG (N = 36,994) and those with an initial non-diagnostic ECG that were diagnosed on a follow-up ECG (N = 4,566).
  
  
  RESULTS
  In general, baseline characteristics and clinical presentations were similar between the 2 groups. For patients with an initial non-diagnostic ECG, 72.4% (n = 3,305) had an ECG diagnostic for STEMI within 90 minutes of their initial ECG. There did not appear to be significant differences in the administration of guideline-recommended treatments for STEMI, in-hospital major bleeding (P = .926), or death (P = .475) between these groups.
  
  
  CONCLUSIONS
  In a national sample of patients diagnosed as having STEMI, 11.0% had an initial non-diagnostic ECG. Of those patients, 72.4% had a follow-up diagnostic ECG within 90 minutes of their initial ECG. There did not appear to be clinically meaningful differences in guidelines-based treatment or major inhospital outcomes between patients diagnosed as having STEMI on an initial ECG and those diagnosed on a follow-up ECG.
authors.affiliation: Section on Cardiology, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA. rriley@wakehealth.edu
authors.forename: Robert F
authors.initials: RF
authors.lastname: Riley
authors.forename: L Kristin
authors.initials: LK
authors.lastname: Newby
authors.forename: Creighton W
authors.initials: CW
authors.lastname: Don
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Roe
authors.forename: DaJuanicia N
authors.initials: DN
authors.lastname: Holmes
authors.forename: Sanjay K
authors.initials: SK
authors.lastname: Gandhi
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kutcher
authors.forename: David M
authors.initials: DM
authors.lastname: Herrington
mesh_terms: D000368:Aged; D000572:American Heart Association; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000188:drug therapy; D010043:Outcome and Process Assessment, Health Care; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States