title: QRS prolongation on the signal-averaged electrocardiogram versus ST-segment changes on the 12-lead electrocardiogram: which is the most sensitive electrocardiographic marker of myocardial ischemia?
abstract: BACKGROUND
  ST-segment changes and QRS prolongation are electrocardiographic (ECG) markers of myocardial ischemia.
  
  
  OBJECTIVE
  This study was undertaken to investigate the appearance of QRS duration changes with or without concomitant ST-segment changes during a typical anginal episode.
  
  
  METHODS
  For this purpose, 126 patients underwent 12-lead surface ECG and signal-averaged electrocardiogram (SAECG) during typical anginal pain as well as at the time the patient was asymptomatic. In both periods, QRS duration and ST-segment changes were evaluated. All patients underwent cardiac catheterization.
  
  
  RESULTS
  Of the 126 patients, 108 (86%) had coronary artery disease (CAD), whereas the remaining 18 (14%) patients had normal coronary arteriograms. During typical anginal pain, 75 of the 108 (70%) patients with CAD and 2 of the 18 (11%) patients with normal coronary arteriograms developed QRS prolongation, whereas 60 of the 108 (56%) patients with CAD and 2 of the 18 (11%) patients with normal coronary vessels developed ST-segment changes. Thus, the sensitivities of QRS prolongation measured by SAECG and of ST-segment changes on the surface ECG for the detection of myocardial ischemia were found to be 70 and 56%, respectively, (p < 0.01), whereas the specificities were both found to be 89% (p = NS).
  
  
  CONCLUSIONS
  During typical anginal pain, QRS prolongation on the SAECG is more sensitive than are ST-segment changes on the ECG for the detection of myocardial ischemia.
authors.affiliation: Department of Cardiology, University of Athens Medical School, Hippokration Hospital, Greece.
authors.forename: A P
authors.initials: AP
authors.lastname: Michaelides
authors.forename: P E
authors.initials: PE
authors.lastname: Dilaveris
authors.forename: Z D
authors.initials: ZD
authors.lastname: Psomadaki
authors.forename: D J
authors.initials: DJ
authors.lastname: Richter
authors.forename: G K
authors.initials: GK
authors.lastname: Andrikopoulos
authors.forename: N
authors.initials: N
authors.lastname: Pitsilides
authors.forename: V
authors.initials: V
authors.lastname: Dounis
authors.forename: C
authors.initials: C
authors.lastname: Stefanadis
authors.forename: P K
authors.initials: PK
authors.lastname: Toutouzas
mesh_terms: D000328:Adult; D000368:Aged; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis*; D011226:Pre-Excitation Syndromes / Q000175:diagnosis; D012680:Sensitivity and Specificity