title: A comparison of the diagnostic performance of the ST/HR hysteresis with cardiopulmonary stress testing parameters in detecting exercise-induced myocardial ischemia.
abstract: BACKGROUND
  Because ST segment depression has limited diagnostic performance at exercise electrocardiography (ECG), ST segment depression/heart rate (ST/HR) hysteresis and cardiopulmonary exercise test (CPET)-derived parameters have been proposed as alternatives to diagnose exercise-induced myocardial ischemia. We compared the diagnostic performance of such parameters.
  
  
  METHODS
  We studied 56 subjects (45 men, 11 women, age 59.7 ± 13.6 years) referred for suspected exercise-induced myocardial ischemia with an equivocal ECG exercise test. All subjects serially underwent CPET and a myocardial single-photon emission computerized tomography (SPECT) perfusion imaging (as the gold standard for ischemia). Maximum ST depression at peak exercise (ST-max), the ST/HR hysteresis, ΔVO2/ΔWR b-b1 slope, ΔVO2/ΔWR (aa1-bb1), VO2/HR flattening duration and other CPET parameters were derived in all subjects.
  
  
  RESULTS
  On the basis of SPECT, 23 subjects (41%) were considered ischemic and 33 subjects (59%) non-ischemic. ST/HR hysteresis was higher (0.026 mV; 95% CI: 0.003 to 0.049 vs -0.016 mV; 95% CI: -0.031 to -0.001 mV) and ST-max was lower (-0.105 mV; 95% CI: -0.158 to -0.052 vs 0.032 mV; 95% CI: -0.001 to -0.066 mV) in ischemic vs non-ischemic subjects (P=0.004 and P=0.001, respectively). Among CPET parameters, ΔVO2/ΔWR b-b(1) slope was lower (9.4 ± 3.8) and ΔVO2/ΔWR (aa(1)-bb(1)) was higher (2.1 ± 2.6) in ischemic vs non-ischemic subjects (11.4 ± 2.3, P=0.005, and 1.1 ± 1.5, P=0.001, respectively). The ST/HR hysteresis had the highest area under the curve value, better (P<0.05) than any other parameters tested, thus showing the highest overall diagnostic performance.
  
  
  CONCLUSIONS
  The ST/HR hysteresis is superior to CPET-derived parameters for detecting exercise-induced myocardial ischemia in patients with equivocal ECG exercise test results.
authors.affiliation: Institute of Cardiology and Center of Excellence on Aging, "G. d'Annunzio" University-Chieti Italy, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Zimarino
authors.forename: Luca
authors.initials: L
authors.lastname: Barnabei
authors.forename: Rosalinda
authors.initials: R
authors.lastname: Madonna
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Palmieri
authors.forename: Francesco
authors.initials: F
authors.lastname: Radico
authors.forename: Alfonso
authors.initials: A
authors.lastname: Tatasciore
authors.forename: Francesco Iachini
authors.initials: FI
authors.lastname: Bellisarii
authors.forename: Gianni Mauro
authors.initials: GM
authors.lastname: Perrucci
authors.forename: Alessandro
authors.initials: A
authors.lastname: Corazzini
authors.forename: Raffaele
authors.initials: R
authors.lastname: De Caterina
mesh_terms: D000368:Aged; D055426:Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography / Q000379:methods / Q000592:standards*; D004562:Electrocardiography / Q000379:methods / Q000592:standards*; D005080:Exercise Test / Q000379:methods / Q000592:standards*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology*