title: Diagnostic and prognostic significance of ischemic electrocardiographic changes with regadenoson-stress myocardial perfusion imaging.
abstract: BACKGROUND
  The diagnostic and prognostic value of regadenoson-induced ST-segment depression (ST↓) is not defined. Due to the low incidence of ST↓ ≥1.0 mm with vasodilator stress, a lower threshold to define ischemic ECG response may provide improved clinical utility.
  
  
  METHODS
  We conducted a retrospective cohort study of patients who underwent regadenoson-stress SPECT myocardial perfusion imaging (MPI) followed by coronary angiography within 6 months. Ischemic ST↓ was defined as ≥0.5 mm. The prevalence of angiographically severe coronary artery disease (CAD) and the rates of major adverse cardiac events (MACE) including cardiac death, myocardial infarction, and coronary revascularization were determined.
  
  
  RESULTS
  In a diagnostic cohort of 629 subjects, 117 (18.6%) had ST↓ ≥0.5 mm. Severe CAD was more prevalent in the ST↓ ≥0.5 vs ST <0.5 group (13.7% vs 5.3%, P = .001). Among patients with normal MPI (n = 229), the prevalence of severe CAD was higher in the ST↓ ≥0.5 group (8.2% vs 2.2%, P = .04). Adjusting for clinical and imaging covariates, ST↓ ≥0.5 mm was independently predictive of severe CAD [odds ratio = 3.37, 95% confidence interval (CI) = 1.67-6.83, P = .001], and provided incremental diagnostic value (Chi square increment = 10.3, P = .001). In an outcome cohort of 748 subjects, after adjusting for clinical and imaging covariates, ST↓ ≥0.5 mm was associated with increased MACE rate in the entire cohort [hazard ratio = 1.41, CI 1.01-1.96, P = .04] and in the subgroup of patients with normal MPI [hazard ratio = 2.2, CI 1.11-4.39, P = .02], and provided incremental prognostic value (Chi square increment = 3.9, P = .049). A diagnostic ST↓ threshold of 0.5 mm provided greater discriminatory capacity than a 1.0 mm cutoff (P = .03).
  
  
  CONCLUSIONS
  Among patients selected to undergo coronary angiography, regadenoson-induced ST↓ ≥0.5 mm was associated with higher rates of severe CAD and MACE, irrespective of MPI finding.
authors.affiliation: Division of Cardiology, John H. Stroger, Jr. Hospital of Cook County, 1901 W. Harrison St. Suite 3620, Chicago, IL, 60612, USA, rami_doukky@rush.edu.
authors.forename: Rami
authors.initials: R
authors.lastname: Doukky
authors.forename: Adebayo
authors.initials: A
authors.lastname: Olusanya
authors.forename: Raj
authors.initials: R
authors.lastname: Vashistha
authors.forename: Abhimanyu
authors.initials: A
authors.lastname: Saini
authors.forename: Ibtihaj
authors.initials: I
authors.lastname: Fughhi
authors.forename: Khaled
authors.initials: K
authors.lastname: Mansour
authors.forename: Abiy
authors.initials: A
authors.lastname: Nigatu
authors.forename: Kara
authors.initials: K
authors.lastname: Confer
authors.forename: Shannon A
authors.initials: SA
authors.lastname: Sims
mesh_terms: D058908:Adenosine A2 Receptor Agonists; D002641:Chicago / Q000453:epidemiology; D004562:Electrocardiography / Q000379:methods / Q000706:statistics & numerical data*; D005080:Exercise Test / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000401:mortality*; D055414:Myocardial Perfusion Imaging / Q000706:statistics & numerical data*; D011379:Prognosis; D011687:Purines; D011720:Pyrazoles; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D015996:Survival Rate; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data
chemical_list: D058908:Adenosine A2 Receptor Agonists; D011687:Purines; D011720:Pyrazoles; C430916:regadenoson