title: SPECT dipyridamole scintigraphy for detecting coronary artery disease in patients with isolated severe aortic stenosis.
abstract: BACKGROUND
  The sensitivity and specificity of non-invasive methods--specifically single-photon emission computed tomography (SPECT) dipyridamole-thallium myocardial perfusion--for detecting coronary artery disease (CAD) in patients with severe aortic stenosis remains unclear. Occasionally, these patients present with atypical angina. Therefore, a CAD diagnosis must be excluded to prevent unnecessary cardiac catheterization.
  
  
  METHODS
  To determine the diagnostic value of SPECT dipyridamole-thallium imaging in this population, we compared the effectiveness of the imaging procedure with that of coronary angiography by prospectively analyzing patients who underwent both procedures. Group 1 included 59 patients who were asymptomatic or had atypical angina; group 2; 51 preoperative aged-matched patients with typical angina. SPECT acquisition was performed 15 min after 0.142 mg/kg/min of dipyridamole infusion completion, and redistribution images were performed 4 h after thallium injection. Two cut-off values of luminal diameter narrowing, >50 and >70%, defined significant CAD.
  
  
  RESULTS
  Coronary angiography with significant CAD (>50%) was present in 15 (25%) group 1 patients and in 16 (32%) group 2 patients (P=NS). The sensitivity was greater in group 2 than in group 1 (56 versus 26%; P=0.001). The specificity, positive and negative predictive value, and accuracy in the groups were similar. CAD of >70% luminal stenosis was present in 11 (19%) group 1 patients and in 12 (23%) group 2 patients (P=NS). The positive predictive value was greater in group 2 than in group 1 (75 versus 43%; P=0.001) but similar sensitivity, specificity, negative predictive value, and accuracy. The likelihood ratio for abnormal test increased in patients with CAD of >70%.
  
  
  CONCLUSIONS
  symptoms of typical angina had significant impact on test sensitivity, positive predictive value and likelihood ratio for abnormal test. Furthermore, SPECT dipyridamole-thallium imaging was a useful non-invasive method to exclude the diagnosis of significant CAD (high specificity) in asymptomatic and symptomatic patients with isolated severe aortic stenosis.
authors.affiliation: Clinical Department, Heart Institute (InCor), University of São Paulo, Medical School, São Paulo, Brazil.
authors.forename: S D
authors.initials: SD
authors.lastname: Avakian
authors.forename: M
authors.initials: M
authors.lastname: Grinberg
authors.forename: J C
authors.initials: JC
authors.lastname: Meneguetti
authors.forename: J A
authors.initials: JA
authors.lastname: Ramires
authors.forename: A P
authors.initials: AP
authors.lastname: Mansur
mesh_terms: D000368:Aged; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D004176:Dipyridamole; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010726:Phosphodiesterase Inhibitors; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D013793:Thallium; D015899:Tomography, Emission-Computed, Single-Photon; D014463:Ultrasonography
chemical_list: D010726:Phosphodiesterase Inhibitors; D004176:Dipyridamole; D013793:Thallium