title: The significance of transient ischemic dilation in the setting of otherwise normal SPECT radionuclide myocardial perfusion images.
abstract: BACKGROUND
  Transient ischemic dilation (TID) in the setting of an abnormal SPECT radionuclide myocardial perfusion imaging (MPI) study is considered a marker of severe and extensive coronary artery disease (CAD). However, the clinical significance of TID and its association with CAD in patients with an otherwise normal MPI study is unclear.
  
  
  METHODS
  From a database of patients who underwent MPI over a 9-year period, 96 without known cardiac history who had normal image perfusion patterns, and who underwent coronary angiography within 6 months, were identified. TID quantitative values were derived. To adjust for varying stress and image protocols, a TID index based on published threshold values was derived for each patient, with >1 considered as TID. We examined the relationship of TID to the presence/extent of CAD, and to a CAD prognostic index. TID was also correlated with patient survival. To address referral bias, survival in a separate cohort of 3,691 patients with a normal perfusion MPI who did not undergo angiography in the 6-month interval was correlated with the presence and severity of TID.
  
  
  RESULTS
  For 28 (29.2%) patients with normal MPI perfusion patterns but with TID, there was no increased incidence of CAD, multivessel or left main disease, or a higher prognostic index compared with no TID. In addition, there was no increased mortality associated with TID in both the angiography cohort and in the patients who did not undergo immediate angiography.
  
  
  CONCLUSIONS
  TID in patients with an otherwise normal SPECT MPI study does not increase the likelihood of CAD, its extent or severity, and is not associated with worsened patient survival.
authors.affiliation: Division of Cardiology/Department of Medicine, Montefiore Medical Center, Bronx, NY, USA.
authors.forename: Carolina
authors.initials: C
authors.lastname: Valdiviezo
authors.forename: Apurva A
authors.initials: AA
authors.lastname: Motivala
authors.forename: Rory
authors.initials: R
authors.lastname: Hachamovitch
authors.forename: Murthy
authors.initials: M
authors.lastname: Chamarthy
authors.forename: Pablo C
authors.initials: PC
authors.lastname: Navarro
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Ostfeld
authors.forename: Mimi
authors.initials: M
authors.lastname: Kim
authors.forename: Mark I
authors.initials: MI
authors.lastname: Travin
mesh_terms: D000328:Adult; D000368:Aged; D017023:Coronary Angiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000209:etiology / Q000401:mortality; D055414:Myocardial Perfusion Imaging; D015899:Tomography, Emission-Computed, Single-Photon