title: Utilization of ST-segment deviation sum and change scores to identify acute myocardial infarction.
abstract: OBJECTIVE
  No information is currently available regarding the optimal cutoff values of the baseline ST-segment deviation sum (STDsum(baseline)) and 60-minute ST-segment deviation change (STDchange(60 min)) for predicting acute myocardial infarction (AMI).
  
  
  METHODS
  A retrospective study was performed in 783 admitted patients with chest pain who had suspected acute coronary syndrome and absence of left ventricular hypertrophy or bundle branch block on the initial electrocardiogram (ECG). The STDsum(baseline) was defined as the sum in millimeters (1 mm = 0.1 mV) of the absolute value of ST-segment deviations in all 12 leads at the initiation of continuous 12-lead ECG monitoring session. The STDchange(60 min) was defined as the absolute value of the difference between the baseline and 60-minute STDsum. Three cutoff values are reported and represent the smallest values in which the positive likelihood ratio (+LR) for AMI was greater than or equal to 5, 10, and 20, respectively.
  
  
  RESULTS
  Acute myocardial infarction occurred in 162 (20.7%) patients. The smallest cutoff value of the STDsum(baseline) for AMI with a +LR equal to or greater than 5, 10, and 20 was 9.6, 12.4, and 14.1 mm, respectively. In the subset of 699 patients without ST-segment elevation AMI on initial ECG, the smallest cutoff value of the STDchange(60 min) for AMI with a +LR equal to or greater than 5, 10, and 20 was 2.4, 3.5, and 7.9 mm, respectively.
  
  
  CONCLUSIONS
  Clinical studies need to be performed to determine if STDsum and STDchange, in conjunction with physician pretest probability of AMI, can be used to select patients who may benefit from emergent reperfusion therapy and other aggressive medical management strategies.
authors.affiliation: Emergency Heart Center, Erlanger Medical Center and Division of Emergency Medicine, University of Tennessee Chattanooga College of Medicine, Chattanooga, TN 37405, USA. francis.fesmire@erlanger.org
authors.forename: Francis M
authors.initials: FM
authors.lastname: Fesmire
mesh_terms: D000046:Academic Medical Centers; D002637:Chest Pain / Q000209:etiology; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D004562:Electrocardiography / Q000295:instrumentation / Q000379:methods*; D004635:Emergency Medicine / Q000458:organization & administration; D004636:Emergency Service, Hospital / Q000458:organization & administration; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy; D018579:Patient Selection; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D013714:Tennessee / Q000453:epidemiology; D013997:Time Factors