title: Diagnostic accuracy of exercise electrocardiogram in patients with left anterior hemi-block.
abstract: BACKGROUND
  Left anterior hemiblock (LAHB) is the most frequent conduction abnormality, but its impact on the diagnostic accuracy of the exercise ECG has not been studied. The aim of our study was to determine the diagnostic accuracy of ST depression for predicting ischaemia in the presence of LAHB.
  
  
  METHODS
  Consecutive patients with known or suspected coronary heart disease undergoing exercise ECG and 99mTc-sestamibi single photon emission computed tomography (SPECT) were included in the analysis. Patients with left bundle branch block, with changes in QRS morphology related to myocardial infarction, and patients who had undergone pharmacological stress testing were excluded.
  
  
  RESULTS
  Of 1532 patients assessed, 567 patients qualified for the analysis. In 69 patients with LAHB, ECG stress testing had lower sensitivity (38% vs 86%) and lower negative predictive value (82% vs 92%) than in patients with normal baseline ECG. The reduction of sensitivity appeared to be similar in patients with isolated LAHB (n=43), in patients with right bundle branch block (n=39), and with bifascicular block (n=26). In contrast, the positive predictive value of the test was excellent.
  
  
  CONCLUSIONS
  The diagnostic accuracy of the exercise ECG for prediction of ischaemia is reduced in patients with LAHB.
authors.affiliation: Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland.
authors.forename: Stefano F
authors.initials: SF
authors.lastname: Rimoldi
authors.forename: Stefano F
authors.initials: SF
authors.lastname: de Marchi
authors.forename: Marc
authors.initials: M
authors.lastname: Gertsch
authors.forename: Etienne
authors.initials: E
authors.lastname: Delacrétaz
mesh_terms: D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000000981:diagnostic imaging; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon