The Significance of Transient Ischemic Dilation in the Setting of Otherwise Normal SPECT Radionuclide Myocardial Perfusion Images

OBJECTIVES: 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. 

PMID: 21327596

Posted in Nuclear Imaging and tagged , , , .

One Comment

  1. They follow two cohorts in this paper. In the first cohort they include patients with negative SPECT with subsequent coronary angiography. I think this must be a pretty odd group of patients, who have a negative SPECT and still go to cath. Nevertheless, in this group they show no difference in severity of coronary artery disease at cath between the transient ischemic dilatation and no transient ischemic dilatation. Nevertheless, both the TID+ and TID- groups had over 10% incidence of multlivessel and/or left main disease at cath, again which makes me think this group is pretty different than your usual negative SPECT group.

    I thought their second group was more interesting. They looked at a cohort of 3961 pateints and showed no difference in survival between groups. Personally, I find this helpful clinically since I often find myself musing over SPECT cases with possible TID and wonder if I’m missing multivessel disease.

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