title: 12-lead ST-segment monitoring vs single-lead maximum ST-segment monitoring for detecting ongoing ischemia in patients with unstable coronary syndromes.
abstract: BACKGROUND
  12-lead ECG monitoring of the ST segment is more sensitive than patients' symptoms for detecting ischemia after thrombolytic therapy or catheter-based interventions, but it is unclear whether monitoring of the single lead showing maximum ST deviation would be as efficacious.
  
  
  OBJECTIVE
  To determine whether monitoring all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes.
  
  
  METHODS
  Continuous 12-lead ST segment monitoring was performed in 422 patients from the onset of myocardial infarction or during balloon inflation in catheter-based interventions until the patient's discharge from the cardiac care unit. Computer-assisted techniques were used to determine (1) which lead showed the maximum ST deviation at the onset of myocardial infarction or during balloon inflation and (2) what proportion of later ischemic events were associated with ST deviation in this lead.
  
  
  RESULTS
  The lead with the maximum ST deviation could be determined in 312 patients (74%). The remaining 110 (26%) had non-Q wave infarction without ST deviation or no ST changes during balloon inflation. During 18,394 hours of 12-lead ST monitoring, 118 (28%) of the 312 patients had a total of 463 ischemic events, 80% of which were silent. Of 377 ischemic events in which a maximum ST lead was detected, 159 (42%) did not show ST deviation in this lead (sensitivity, 58%; 95% CI, 53%-63%). Routine monitoring of leads V1 and II showed ST deviation in only 152 of the 463 events (sensitivity, 33%; 95% CI, 29%-37%).
  
  
  CONCLUSIONS
  Monitoring of all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes.
authors.affiliation: Department of Physiological Nursing, University of California, San Francisco, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Drew
authors.forename: M M
authors.initials: MM
authors.lastname: Pelter
authors.forename: M G
authors.initials: MG
authors.lastname: Adams
authors.forename: S F
authors.initials: SF
authors.lastname: Wung
authors.forename: T M
authors.initials: TM
authors.lastname: Chou
authors.forename: C L
authors.initials: CL
authors.lastname: Wolfe
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D006328:Cardiac Catheterization / Q000009:adverse effects; D003663:Decision Trees; D004562:Electrocardiography / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy; D011446:Prospective Studies; D012008:Recurrence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted