title: Designing prehospital ECG systems for acute coronary syndromes. Lessons learned from clinical trials involving 12-lead ST-segment monitoring.
abstract: BACKGROUND
  Clinical trials in prehospital electrocardiography have focused primarily on ST elevation myocardial infarction (STEMI). The aims of this study were to determine, in patients presenting to the emergency department with acute coronary syndrome (ACS), the (1) relative frequency of various ACS types and (2) sensitivity of conventional ST-T criteria for diagnosing ischemia in non-STEMI or unstable angina.
  
  
  METHODS
  A secondary analysis was conducted using data from prospective trials involving 12-lead ST monitoring.
  
  
  RESULTS
  Of 968 patients with ACS, 120 (12%) were STEMI, 289 (30%) were non-STEMI, and 559 (58%) were unstable angina. Conventional electrocardiogram (ECG) criteria were insensitive (sensitivity, 20%) for detecting ischemia in patients with non-STEMI or unstable angina. There was no ischemia on the initial ECG in 85 patients who had subsequent events with ST monitoring.
  
  
  CONCLUSIONS
  Non-STEMI and unstable angina are the most prevalent types of ACS. The initial ECG is insensitive for detecting ischemia in this population. Transient myocardial ischemia detected with ST monitoring commonly occurs in patients without ischemia on the initial ECG. ST monitoring should be considered in designing prehospital ECG systems.
authors.affiliation: Department of Physiological Nursing, University of California, San Francisco, CA 94143, USA. barbara.drew@nursing.ucsf.edu
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Drew
authors.forename: Michele M
authors.initials: MM
authors.lastname: Pelter
authors.forename: Eunyoung
authors.initials: E
authors.lastname: Lee
authors.forename: Jessica
authors.initials: J
authors.lastname: Zegre
authors.forename: Daniel
authors.initials: D
authors.lastname: Schindler
authors.forename: Kirsten E
authors.initials: KE
authors.lastname: Fleischmann
mesh_terms: D000208:Acute Disease; D002986:Clinical Trials as Topic; D003327:Coronary Disease / Q000175:diagnosis* / Q000503:physiopathology; D004562:Electrocardiography; D004632:Emergency Medical Services / Q000379:methods*; D006801:Humans; D017202:Myocardial Ischemia / Q000175:diagnosis; D011446:Prospective Studies; D012495:San Francisco; D012680:Sensitivity and Specificity; D013577:Syndrome