title: Emergency medical service predictive instrument-aided diagnosis and treatment of acute coronary syndromes and ST-segment elevation myocardial infarction in the IMMEDIATE trial.
abstract: BACKGROUND
  A challenge for emergency medical service (EMS) is accurate identification of acute coronary syndromes (ACS) and ST-segment elevation myocardial infarction (STEMI) for immediate treatment and transport. The electrocardiograph-based acute cardiac ischemia time-insensitive predictive instrument (ACI-TIPI) and the thrombolytic predictive instrument (TPI) have been shown to improve diagnosis and treatment in emergency departments (EDs), but their use by paramedics in the community has been less studied.
  
  
  OBJECTIVE
  To identify candidates for participation in the Immediate Myocardial Metabolic Enhancement During Initial Assessment and Treatment in Emergency Care (IMMEDIATE) Trial, we implemented EMS use of the ACI-TIPI and the TPI in out-of-hospital electrocardiographs and evaluated its impact on paramedic on-site identification of ACS and STEMI as a community-based approach to improving emergency cardiac care.
  
  
  METHODS
  Ambulances in the study municipalities were outfitted with electrocardiographs with ACI-TIPI and TPI software. Using a before-after quasi-experimental design, in Phase 1, for seven months, paramedics were provided with the ACI-TIPI/TPI continuous 0-100% predictions automatically printed on electrocardiogram (ECG) text headers to supplement their identification of ACS; in Phase 2, for 11 months, paramedics were told to identify ACS based on an ACI-TIPI cutoff probability of ACS ≥ 75% and/or TPI detection of STEMI. In Phase 3, this cutoff approach was used in seven additional municipalities. Confirmed diagnoses of ACS, acute myocardial infarction (AMI), and STEMI were made by blinded physician review for 100% of patients.
  
  
  RESULTS
  In Phase 1, paramedics identified 107 patients as having ACS; in Phase 2, 104. In Phase 1, 45.8% (49) of patients so identified had ACS confirmed, which increased to 76.0% (79) in Phase 2 (p < 0.001). Of those with ACS, 59.2% (29) had AMI in Phase 1 versus 84.8% (67) with AMI in Phase 2 (p < 0.01), and STEMI was confirmed in 40.8% (20) versus 68.4% (54), respectively (p < 0.01). In Phase 3, of 226 patients identified by paramedics as having ACS, 74.3% (168) had ACS confirmed, of whom 81.0% (136) had AMI and 65.5% (110) had STEMI. Among patients with ACS, the proportion who received percutaneous coronary intervention (PCI) was 30.6% (15) in Phase 1, increasing to 57.0% (45) in Phase 2 (p < 0.004) and 50.6% (85) in Phase 3, and the proportions of patients with STEMI receiving PCI rose from 75.0% (15) to 83.3% (45) (p < 0.4) and 82.7% (91).
  
  
  CONCLUSIONS
  In a wide range of EMS systems, use of electrocardiographs with ACI-TIPI and TPI decision support using a 75% ACI-TIPI cutoff improves paramedic diagnostic performance for ACS, AMI, and STEMI and increases the proportions of patients who receive PCI.
authors.affiliation: Center for Cardiovascular Health Services Research, Institute for Clinical Research and Health Policy Studies, Tufts Medical Center and Tufts University School of Medicine, Boston, Massachusetts 02111, USA. hselker@tuftsmedicalcenter.org
authors.forename: Harry P
authors.initials: HP
authors.lastname: Selker
authors.forename: Joni R
authors.initials: JR
authors.lastname: Beshansky
authors.forename: Robin
authors.initials: R
authors.lastname: Ruthazer
authors.forename: Patricia R
authors.initials: PR
authors.lastname: Sheehan
authors.forename: Assaad J
authors.initials: AJ
authors.lastname: Sayah
authors.forename: James M
authors.initials: JM
authors.lastname: Atkins
authors.forename: Tom P
authors.initials: TP
authors.lastname: Aufderheide
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Pirrallo
authors.forename: Ralph B
authors.initials: RB
authors.lastname: D'Agostino
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Massaro
authors.forename: John L
authors.initials: JL
authors.lastname: Griffith
mesh_terms: D054058:Acute Coronary Syndrome / Q000175:diagnosis* / Q000188:drug therapy / Q000628:therapy; D002637:Chest Pain; D016009:Chi-Square Distribution; D020000:Decision Support Systems, Clinical; D003936:Diagnosis, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D004562:Electrocardiography / Q000295:instrumentation* / Q000379:methods; D004634:Emergency Medical Technicians / Q000706:statistics & numerical data*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000188:drug therapy / Q000628:therapy; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012984:Software; D013997:Time Factors