title: Acute beta-blockade reduces the extent and severity of myocardial perfusion defects with dipyridamole Tc-99m sestamibi SPECT imaging.
abstract: OBJECTIVE
  The goal of this study was to examine the effect of acute beta-blockade on dipyridamole Tc-99m sestamibi myocardial perfusion imaging (DMPI).
  
  
  BACKGROUND
  Studies suggest that antianginal drugs may reduce the presence and severity of myocardial perfusion defects with dipyridamole stress. However, there are no data regarding specific drugs.
  
  
  METHODS
  Patients with catheterization-proven coronary artery disease (CAD) were enrolled in this prospective, double-blind, placebo-controlled study and randomly assigned to DMPI after placebo, low-dose metoprolol (up to 10 mg), and high-dose metoprolol (up to 20 mg). Patients underwent one Tc-99m sestamibi study at rest on a separate day. The interval between DMPI studies was <or=14 days. Images were interpreted by three observers blinded to clinical data using a 17-segment, five-point model. For each image, a summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) were calculated (SDS = SSS - SRS). Images with an SSS <4 were considered normal.
  
  
  RESULTS
  Twenty-one patients completed all four Tc-99m sestamibi studies. The sensitivity of DMPI for detection of CAD was 85.7% with placebo versus 71.4% with low- and high-dose metoprolol. In comparison with placebo, the SSS was significantly lower (p < 0.05) with low- and high-dose metoprolol (12.0 +/- 10.1 vs. 8.7 +/- 9.0 and 9.3 +/- 10.6, respectively). The SDS also was significantly lower (8.4 +/- 8.8 with placebo vs. 5.0 +/- 6.7 [p < 0.001] and 5.4 +/- 7.9 [p < 0.01] with low- and high-dose metoprolol, respectively).
  
  
  CONCLUSIONS
  The presence and severity of CAD may be underestimated in patients receiving beta-blocker therapy undergoing dipyridamole stress myocardial perfusion imaging.
authors.affiliation: Department of Nuclear Medicine, Centre Hospitalier de l'Université de Montréal (pavillon Hotel-Dieu), Montréal, Canada. rtaillefer@hotmail.com
authors.forename: Raymond
authors.initials: R
authors.lastname: Taillefer
authors.forename: Alan W
authors.initials: AW
authors.lastname: Ahlberg
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Masood
authors.forename: C Michael
authors.initials: CM
authors.lastname: White
authors.forename: Isabella
authors.initials: I
authors.lastname: Lamargese
authors.forename: Jeffrey F
authors.initials: JF
authors.lastname: Mather
authors.forename: Carol C
authors.initials: CC
authors.lastname: McGill
authors.forename: Gary V
authors.initials: GV
authors.lastname: Heller
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D003327:Coronary Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D004176:Dipyridamole; D004311:Double-Blind Method; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon; D014665:Vasodilator Agents
chemical_list: D000319:Adrenergic beta-Antagonists; D019275:Radiopharmaceuticals; D014665:Vasodilator Agents; D004176:Dipyridamole; D017256:Technetium Tc 99m Sestamibi; D008790:Metoprolol