title: Treadmill exercise produces larger perfusion defects than dipyridamole stress N-13 ammonia positron emission tomography.
abstract: OBJECTIVE
  The aim of this study was to compare treadmill exercise (TEX) and dipyridamole stress on the uptake and retention of N-13 ammonia.
  
  
  BACKGROUND
  Size and severity of stress-induced myocardial perfusion defects are clinically important. Because ammonia uptake and retention seems to be related to perfusion, viability, and metabolism, exercise stress might induce larger perfusion defects than dipyridamole stress.
  
  
  METHODS
  Twenty-six patients underwent TEX and dipyridamole stress N-13 ammonia positron emission tomography (PET). Images were assessed with a 17-segment model and a five-point score. Summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) were calculated. Left ventricular (LV) defect sizes were measured quantitatively with a 70% threshold for abnormal perfusion.
  
  
  RESULTS
  Compared with dipyridamole stress, TEX yielded larger SSS (9.1 +/- 5.7 vs. 6.9 +/- 5.9; p < 0.01), SDS (5.8 +/- 4.7 vs. 3.7 +/- 4.6; p < 0.02), and percentage of LV stress defect (19.3 +/- 11.5% vs. 13.8 +/- 13.6%; p < 0.02).
  
  
  CONCLUSIONS
  In patients achieving adequate exercise, TEX N-13 ammonia PET myocardial perfusion imaging (MPI) yields larger stress perfusion defects than dipyridamole stress and might reflect the true myocardial ischemic burden. Treadmill exercise might be the preferred method of stress for routine N-13 ammonia PET MPI.
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada. bchow@ottawaheart.ca
authors.forename: Benjamin J W
authors.initials: BJ
authors.lastname: Chow
authors.forename: Rob S
authors.initials: RS
authors.lastname: Beanlands
authors.forename: Andrea
authors.initials: A
authors.lastname: Lee
authors.forename: Jean N
authors.initials: JN
authors.lastname: DaSilva
authors.forename: Robert A
authors.initials: RA
authors.lastname: deKemp
authors.forename: Abdulkareem
authors.initials: A
authors.lastname: Alkahtani
authors.forename: Terrence D
authors.initials: TD
authors.lastname: Ruddy
mesh_terms: D000368:Aged; D000641:Ammonia; D003326:Coronary Circulation; D004176:Dipyridamole; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009590:Nitrogen Radioisotopes; D049268:Positron-Emission Tomography / Q000379:methods*; D016037:Single-Blind Method; D014665:Vasodilator Agents
chemical_list: D009590:Nitrogen Radioisotopes; D014665:Vasodilator Agents; D004176:Dipyridamole; D000641:Ammonia