title: Reverse redistribution on exercise thallium scintigraphy: relationship to coronary patency and ventricular function after myocardial infarction.
abstract: OBJECTIVE
  To define prevalence, pathophysiology and relation to thrombolytic therapy of reverse redistribution (appearance of a new, or worsening of an existing, scintigraphic defect on 4 h delayed images compared with the stress thallium image).
  
  
  METHODS
  Randomized, double-blind, placebo-controlled trial.
  
  
  METHODS
  Referral centre.
  
  
  METHODS
  Sixty-three patients with acute myocardial infarction.
  
  
  METHODS
  Tomographic exercise thallium scintigraphy, radionuclide angiography, and quantitative coronary angiography.
  
  
  RESULTS
  Tomographic exercise thallium scintigraphy performed at day 10 revealed fixed defects in 15 patients, reversible defects in 22 patients and reverse redistribution in 26 patients; no difference in treatment assignment (tissue plasminogen activator versus placebo) was found among the three groups. Left ventricular function was similar in patients with fixed or reversible defects and reverse redistribution; global ejection fraction was 48 +/- 14, 51 +/- 10 and 48 +/- 5%, respectively, and regional infarct ejection fraction was 36 +/- 15, 40 +/- 13 and 37 +/- 18%, respectively. However, nitroglycerin administration resulted in a significantly greater improvement in regional ejection fraction in reverse redistribution patients (5 +/- 4%) than that in patients with fixed defect (2 +/- 5%, P < 0.05) or reversible defects (3 +/- 5%, P < 0.05). The infarct-related artery had a greater cross-sectional area in reverse redistribution patients (1.5 +/- 1.42 mm2) compared with those with reversible defects (0.50 +/- 0.26 mm2, P < 0.05), but was similar to fixed defect patients (1.04 +/- 0.88).
  
  
  CONCLUSIONS
  Reverse redistribution on tomographic thallium scintigraphy is a frequent phenomenon (occurring in 40% of patients following acute myocardial infarction) and is independent of thrombolytic therapy. Patients with reverse redistribution have a more widely patent infarct-related artery and similar ventricular function, but significantly greater functional improvement following nitroglycerin administration compared with those with reversible or fixed defects. These data suggest myocardial salvage within the infarct zone in some patients with reverse redistribution.
authors.affiliation: Division of Cardiology, St Michael's Hospital, Toronto, Ontario.
authors.forename: A
authors.initials: A
authors.lastname: Langer
authors.forename: R J
authors.initials: RJ
authors.lastname: Burns
authors.forename: M R
authors.initials: MR
authors.lastname: Freeman
authors.forename: P
authors.initials: P
authors.lastname: Liu
authors.forename: C D
authors.initials: CD
authors.lastname: Morgan
authors.forename: R
authors.initials: R
authors.lastname: Wilson
authors.forename: P W
authors.initials: PW
authors.lastname: Armstrong
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization; D003326:Coronary Circulation / Q000502:physiology*; D004285:Dogs; D004311:Double-Blind Method; D005080:Exercise Test; D006801:Humans; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012189:Retrospective Studies; D013793:Thallium; D015899:Tomography, Emission-Computed, Single-Photon; D014654:Vascular Patency; D016277:Ventricular Function, Left / Q000502:physiology*
chemical_list: D013793:Thallium