title: Cardiovascular outcomes after pharmacologic stress myocardial perfusion imaging.
abstract: BACKGROUND
  While pharmacologic stress single photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) is used for noninvasive evaluation of patients who are unable to perform treadmill exercise, its impact on net reclassification improvement (NRI) of prognosis is unknown.
  
  
  METHODS
  We evaluated the prognostic value of pharmacologic stress MPI for prediction of cardiovascular death or non-fatal myocardial infarction (MI) within 1 year at a single-center, university-based laboratory. We examined continuous and categorical NRI of pharmacologic SPECT-MPI for prediction of outcomes beyond clinical factors alone.
  
  
  RESULTS
  Six thousand two hundred forty patients (median age 66 years [IQR 56-74], 3466 men) were studied and followed for 5963 person-years. SPECT-MPI variables associated with increased risk of cardiovascular death or non-fatal MI included summed stress score, stress ST-shift, and post-stress resting left ventricular ejection fraction ≤50%. Compared to a clinical model which included age, sex, cardiovascular disease, risk factors, and medications, model χ(2) (210.5 vs. 281.9, P < .001) and c-statistic (0.74 vs. 0.78, P < .001) were significantly increased by addition of SPECT-MPI predictors (summed stress score, stress ST-shift and stress resting left ventricular ejection fraction). SPECT-MPI predictors increased continuous NRI by 49.4% (P < .001), reclassifying 66.5% of patients as lower risk and 32.8% as higher risk of cardiovascular death or non-fatal MI. Addition of MPI predictors to clinical factors using risk categories, defined as <1%, 1% to 3%, and >3% annualized risk of cardiovascular death or non-fatal MI, yielded a 15.0% improvement in NRI (95% CI 7.6%-27.6%, P < .001).
  
  
  CONCLUSIONS
  Pharmacologic stress MPI substantially improved net reclassification of cardiovascular death or MI risk beyond that afforded by clinical factors.
authors.affiliation: Robert J. Burns Nuclear Cardiology Laboratory, University of Toronto, Toronto, Canada; Joint Department of Medical Imaging and Peter Munk Cardiac Centre, University Health Network, University of Toronto, Toronto, Canada; Institute for Clinical Evaluative Sciences, University of Toronto, Toronto, Canada. Electronic address: dlee@ices.on.ca.
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Lee
authors.affiliation: Robert J. Burns Nuclear Cardiology Laboratory, University of Toronto, Toronto, Canada; Joint Department of Medical Imaging and Peter Munk Cardiac Centre, University Health Network, University of Toronto, Toronto, Canada; Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Canada.
authors.forename: Mansoor
authors.initials: M
authors.lastname: Husain
authors.affiliation: Institute for Clinical Evaluative Sciences, University of Toronto, Toronto, Canada.
authors.forename: Xuesong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute for Clinical Evaluative Sciences, University of Toronto, Toronto, Canada.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Austin
authors.affiliation: Robert J. Burns Nuclear Cardiology Laboratory, University of Toronto, Toronto, Canada; Joint Department of Medical Imaging and Peter Munk Cardiac Centre, University Health Network, University of Toronto, Toronto, Canada.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Iwanochko
mesh_terms: D000368:Aged; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D004562:Electrocardiography; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D009864:Ontario / Q000453:epidemiology; D011379:Prognosis; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D015996:Survival Rate; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods