title: Prospective evaluation of a new protocol for the provisional use of perfusion imaging with exercise stress testing.
abstract: OBJECTIVE
  Previous literature suggests that myocardial perfusion imaging (MPI) adds little to the prognosis of patients who exercise >10 metabolic equivalents (METs) during stress testing. With this in mind, we prospectively tested a provisional injection protocol in emergency department (ED) patients presenting for the evaluation of chest pain in which a patient would not receive an injection of radioisotope if adequate exercise was achieved without symptoms and a negative ECG response.
  
  
  METHODS
  All patients who presented to the ED over a 5-year period who were referred for stress testing as part of their ED evaluation were included. Patients considered for a provisional protocol were: exercise stress, age <65 years, no known coronary artery disease, and an interpretable rest ECG. Criteria for not injecting included a maximal predicted heart rate ≥85%, ≥10 METs of exercise, no anginal symptoms during stress, and no ECG changes. Groups were compared based on stress test results, all-cause and cardiac mortality, follow-up cardiac testing, subsequent revascularization, and cost.
  
  
  RESULTS
  A total of 965 patients were eligible with 192 undergoing exercise-only and 773 having perfusion imaging. After 41.6 ± 19.6 months of follow-up, all-cause mortality was similar in the exercise-only versus the exercise plus imaging group (2.6% vs. 2.1%, p = 0.59). There were no cardiac deaths in the exercise-only group. At 1 year there was no difference in the number of repeat functional stress tests (1.6% vs. 2.1%, p = 0.43), fewer angiograms (0% vs. 4.0%, p = 0.002), and a significantly lower cost ($65 ± $332 vs $506 ± $1,991, p = 0.002; values are in US dollars) in the exercise-only group. The radiation exposure in the exercise plus imaging group was 8.4 ± 2.1 mSv.
  
  
  CONCLUSIONS
  A provisional injection protocol has a very low mortality, few follow-up diagnostic tests, and lower cost compared to standard imaging protocols. If adopted it would decrease radiation exposure, save time and decrease health-care costs without jeopardizing prognosis.
authors.affiliation: Division of Cardiology (Henry Low Heart Center), Hartford Hospital, South Building 2nd Floor, Hartford, CT, 06102, USA, lane.duvall@hhchealth.org.
authors.forename: W Lane
authors.initials: WL
authors.lastname: Duvall
authors.forename: John A
authors.initials: JA
authors.lastname: Savino
authors.forename: Elliot J
authors.initials: EJ
authors.lastname: Levine
authors.forename: Luke K
authors.initials: LK
authors.lastname: Hermann
authors.forename: Lori B
authors.initials: LB
authors.lastname: Croft
authors.forename: Milena J
authors.initials: MJ
authors.lastname: Henzlova
mesh_terms: D000328:Adult; D002637:Chest Pain / Q000175:diagnosis / Q000000981:diagnostic imaging*; D002985:Clinical Protocols; D004562:Electrocardiography; D004636:Emergency Service, Hospital; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000008:administration & dosage
chemical_list: D019275:Radiopharmaceuticals