title: Comparison of the predischarge exercise thallium-201 perfusion defect after myocardial infarction with myocardium at risk measured during acute infarction with technetium-99m sestamibi imaging.
abstract: BACKGROUND
  Exercise thallium-201 imaging provides a noninvasive estimate of the amount of myocardium presumed to be at risk of infarcting should a complete occlusion of the coronary stenosis occur. The relationship between the size of the exercise thallium perfusion defect and the extent of myocardium supplied by a diseased coronary artery has not been established. This study evaluates that presumed correlation.
  
  
  METHODS
  Patients were injected intravenously with technetium-99m sestamibi during acute myocardial infarction before thrombolysis or conventional therapy to quantify the myocardium at risk. Twenty-six patients who underwent risk-area assessment subsequently underwent clinically driven, predischarge, submaximal exercise imaging with thallium-201. The exercise testing was performed on day 7 +/- 2 days. A conventional polar map display was used to quantify the perfusion defect.
  
  
  RESULTS
  The myocardium at risk determined by technetium-99m sestamibi at the time of infarction was 30% +/- 20% of the left ventricle. The mean exercise thallium-201 defect was 34% +/- 22% of the left ventricle. The exercise defect tended to be slightly larger than the myocardium at risk (4% +/- 10% of the left ventricle, P =.05). There was a close correlation between the 2 measurements (r = 0.89, SE = 9.4, P <.0001).
  
  
  CONCLUSIONS
  This study shows a close correlation between the myocardium "at risk" assessed acutely by technetium-99m sestamibi and the "presumed at-risk area" determined by thallium-201 imaging on predischarge exercise testing. This finding supports the concept that the size of the exercise thallium defect caused by coronary stenosis indicates the likely size of a myocardial infarction resulting from occlusion of that stenosis.
authors.affiliation: Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Foundation, Rochester, MN 55905, USA. alapeyre@mayo.edu
authors.forename: André C
authors.initials: AC
authors.lastname: Lapeyre
authors.forename: Mark A
authors.initials: MA
authors.lastname: Evans
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Christian
authors.forename: John R
authors.initials: JR
authors.lastname: Daley
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Gibbons
mesh_terms: D000328:Adult; D000368:Aged; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000503:physiopathology; D015425:Myocardial Reperfusion; D011446:Prospective Studies; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D012306:Risk; D017256:Technetium Tc 99m Sestamibi; D013794:Thallium Radioisotopes; D015912:Thrombolytic Therapy
chemical_list: D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes; D017256:Technetium Tc 99m Sestamibi