title: Interrelation of ST-segment depression during bicycle ergometry and extent of myocardial ischaemia by myocardial perfusion SPECT.
abstract: OBJECTIVE
  The aim of this study was to compare ST-segment depression (STD) during bicycle ergometry and extent of myocardial ischaemia assessed by myocardial perfusion SPECT (MPS) in a large patient cohort.
  
  
  METHODS
  Consecutive patients (n = 955) referred for MPS with bicycle ergometry and interpretable stress ECG were evaluated with respect to ECG and MPS findings of ischaemia. The maximal STD was recorded and exercise ECG was considered ischaemic if STD was horizontal or downsloping (>or=1 mm). MPS was interpreted using a 20-segment model with a scale of 0 to 4. A summed stress (SSS), summed rest (SRS) and summed difference score (SDS = SSS-SRS, e.g. extent of ischaemia) were derived. Ischaemia was defined as an SDS >or= 2.
  
  
  RESULTS
  An exercise-induced STD was present in 215 patients (22%) and myocardial ischaemia on MPS was present in 366 patients (38%). The extent of ST-segment depression and the number of ECG leads with significant STD were each strongly and significantly associated with increasing severity of ischaemia and the number of coronary territories involved (p < 0.01 for all correlations).
  
  
  CONCLUSIONS
  These data demonstrate a strong correlation between the extent of STD, number of ischaemic leads and severity of myocardial ischaemia as assessed by MPS during bicycle ergometry.
authors.affiliation: Cardiology Department, University Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland.
authors.forename: Stefano
authors.initials: S
authors.lastname: Muzzarelli
authors.forename: Matthias Emil
authors.initials: ME
authors.lastname: Pfisterer
authors.forename: Jan
authors.initials: J
authors.lastname: Müller-Brand
authors.forename: Michael Johannes
authors.initials: MJ
authors.lastname: Zellweger
mesh_terms: D015331:Cohort Studies; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D055414:Myocardial Perfusion Imaging; D015899:Tomography, Emission-Computed, Single-Photon