title: Predictive value of exercise myocardial perfusion imaging in the Medicare population: the impact of the ability to exercise.
abstract: BACKGROUND
  Although the prognostic value of quantitative single photon emission computed tomography myocardial perfusion imaging (MPI) with exercise and pharmacologic stress is well established, the prognostic and management value in the Medicare age population is less clear.
  
  
  METHODS
  The prospectively populated Cleveland Clinic nuclear cardiology database was used to identify 5,994 consecutive pateints, age >65 years [1,664 (28%) exercise MPI, mean age 72.4±5.1, 74% male], who underwent MPI between January 2004 and January 2008. Clinical baseline variables, post test 90 days revascularization and MPI variables were analyzed. Overall and stratified nonparametric survival estimates were obtained by Kaplan-Meier method. Median follow-up time was 2.4 years. Parametric hazard modeling with bootstrap bagging methods was used to determine prognostic variables predicting mortality.
  
  
  RESULTS
  There was no difference in mortality in patients with an abnormal MPI vs. those with normal MPI. Amongst the patients who underwent exercise MPI, there were 103 (6%) deaths and 121 (8.2%) revascularizations. Only lower exercise capacity (<7 METs) and higher end systolic volume (ESV) predicted mortality. Although a larger amount of ischemia influenced down stream revascularization ischemia, revascularization of patients with an abnormal exercise MPI did not offer a survival benefit (log rank P value=0.01).
  
  
  CONCLUSIONS
  In the a Medicare age population, exercise MPI perfusion variables influenced rates of revascularization but failed to provide incremental significant risk-stratification beyond exercise capacity. Maximum METs achieved appears to be a better predictor of survival.
authors.affiliation: Cleveland Clinic, Department of Cardiovascular Medicine, Cleveland, OH 44195, USA.
authors.forename: Deborah H
authors.initials: DH
authors.lastname: Kwon
authors.affiliation: Cleveland Clinic, Department of Cardiovascular Medicine, Cleveland, OH 44195, USA.
authors.forename: Venu
authors.initials: V
authors.lastname: Menon
authors.affiliation: Cleveland Clinic, Department of Cardiovascular Medicine, Cleveland, OH 44195, USA.
authors.forename: Penny
authors.initials: P
authors.lastname: Houghtaling
authors.affiliation: Cleveland Clinic, Department of Cardiovascular Medicine, Cleveland, OH 44195, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Lieber
authors.affiliation: Cleveland Clinic, Department of Cardiovascular Medicine, Cleveland, OH 44195, USA.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Brunken
authors.affiliation: Cleveland Clinic, Department of Cardiovascular Medicine, Cleveland, OH 44195, USA.
authors.forename: Manuel D
authors.initials: MD
authors.lastname: Cerqueira
authors.affiliation: Cleveland Clinic, Department of Cardiovascular Medicine, Cleveland, OH 44195, USA.
authors.forename: Wael A
authors.initials: WA
authors.lastname: Jaber
keywords: Cardiovascular outcomes; exercise testing; prognosis; revascularization; single-photon emission computed tomography