title: Analysis of ST/HR hysteresis improves long-term prognostic value of exercise ECG test.
abstract: BACKGROUND
  ST/HR hysteresis is one of the better diagnostic exercise ECG variables for coronary artery disease. This study evaluates the long-term prognostic value of ST/HR hysteresis in predicting acute myocardial infarction (AMI) and all-cause mortality in men and women.
  
  
  METHODS
  The study population consisted of 8317 patients who had undergone routine exercise test on bicycle ergometer at one Swedish centre. Information on AMI and all-cause mortality was obtained from national Swedish registers covering a mean follow-up period of 9.5 years.
  
  
  RESULTS
  The adjusted hazard ratio for AMI at a diagnostic cut point of ≤-20 µV for ST/HR hysteresis was 1.88 (95% CI, 1.62-2.17) in men and 2.31 (95% CI, 1.83-2.91) in women. For all-cause death the adjusted hazard ratio was 1.72 (95% CI, 1.52-1.96) in men and 1.90 (95% CI, 1.57-2.29) in women. The corresponding hazard ratios for ST-segment depression with horizontal or down-sloping ST-segment, ST-segment depression, ST/HR index, and ST/HR slope were lower. For comparison, the adjusted hazard ratio for AMI using maximal workload in percent of predicted was 2.02 (95% CI, 1.77-2.32) in men and 2.14 (95% CI, 1.71-2.67) in women. Area under the ROC curves for prediction of AMI was significantly larger using ST/HR hysteresis than using any of three other evaluated ECG indicators.
  
  
  CONCLUSIONS
  ST/HR hysteresis appears to improve the prognostic ability of an exercise ECG test for AMI and all-cause mortality in a long-term perspective compared to conventional ST-segment and ST/HR indicators in both genders and clearly more markedly in women.
authors.affiliation: Department of Medical Engineering, School of Technology and Health, Royal Institute of Technology, Stockholm, Sweden. hakan.kronander@dll.se
authors.forename: Håkan
authors.initials: H
authors.lastname: Kronander
authors.forename: Niklas
authors.initials: N
authors.lastname: Hammar
authors.forename: Werner
authors.initials: W
authors.lastname: Fischer-Colbrie
authors.forename: Jacek
authors.initials: J
authors.lastname: Nowak
authors.forename: Lars-Åke
authors.initials: LÅ
authors.lastname: Brodin
authors.forename: Håkan
authors.initials: H
authors.lastname: Elmqvist
mesh_terms: D000328:Adult; D000368:Aged; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012042:Registries; D013997:Time Factors