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Transient Ischemic Dilation of the Left Ventricle on SPECT: Correlation with Findings at Coronary CT Angiography
William T Halligan1, Pamela B Morris1, U Joseph Schoepf2
1Heart and Vascular Center, Medical University of South Carolina, Charleston, South Carolina.
Insights
Transient ischemic dilation (TID) on normal cardiac SPECT MPI scans does not indicate more coronary artery disease or higher risk of major adverse cardiac events. This finding suggests TID in normal perfusion studies may not require further cardiac CT investigation for atherosclerosis.
Area of Science:
- Cardiology
- Radiology
- Nuclear Medicine
Background:
- Transient ischemic dilation (TID) on stress-rest cardiac SPECT myocardial perfusion imaging (MPI) is linked to cardiovascular risk.
- The significance of TID in normal SPECT MPI studies remains unclear.
- Cardiac CT can assess coronary atherosclerosis and stenosis.
Purpose of the Study:
- To evaluate the prevalence of atherosclerotic lesions and coronary artery stenosis in patients with TID on SPECT MPI, with or without perfusion defects.
- To determine if TID in normal SPECT MPI studies is associated with increased cardiovascular risk.
Main Methods:
- A retrospective analysis of 1,553 patients who underwent both cardiac CT and SPECT MPI within one month.
- Patients with pathologic TID values (≥1.18 for men, ≥1.22 for women) were compared to TID-negative controls.
- Coronary CT angiography assessed plaque presence, composition, and stenosis severity.
Main Results:
- TID-positive patients (n=30) showed no significant differences in atherosclerosis extent, coronary artery stenosis, or calcium score compared to TID-negative controls (n=60).
- TID-positive patients with normal perfusion (n=20) also showed no significant differences in CT measures compared to TID-negative normal perfusion controls (n=48).
- No significant difference in major adverse cardiac events was observed between TID-positive and TID-negative groups, or within subgroups with normal perfusion.
Conclusions:
- Transient ischemic dilation (TID) in the context of a normal SPECT MPI study does not correlate with a greater extent of coronary artery disease.
- TID on normal SPECT MPI does not predict an increased risk of future major adverse cardiac events.
- Cardiac CT assessment of coronary artery disease is not indicated solely based on TID in normal SPECT MPI studies.
Unlabelled:
Transient ischemic dilation (TID) in the setting of abnormal stress-rest cardiac SPECT myocardial perfusion imaging (MPI) has been linked with increased cardiovascular risk. However, the significance of TID in the setting of an otherwise normal SPECT MPI study has not been clearly established. In this study, cardiac CT was used to evaluate the prevalence of atherosclerotic lesions and the severity of coronary artery stenosis in patients with TID of the left ventricle with or without associated myocardial perfusion defects on SPECT MPI.
Methods:
The study population consisted of 1,553 consecutive patients who had undergone both cardiac CT and SPECT MPI within 1 mo between January 1, 2006, and September 1, 2011. Patients included in the study group had a pathologic TID value defined as ≥1.18 for men and ≥1.22 for women. Coronary CT angiography was used to evaluate each coronary segment for the presence and composition of atherosclerotic plaque and the degree of coronary stenosis. TID-positive patients were compared with a 2:1 risk-factor-matched-pair control cohort without TID.
Results:
TID was identified in 30 patients who were compared with TID-negative risk-factor-matched controls (n = 60). When compared with the TID-negative control cohort, TID-positive patients had no significant differences in the presence and extent of atherosclerosis, the degree of coronary artery stenosis, or the calcium score at cardiac CT. Similarly, there were no significant differences in these CT measures in TID-positive patients with a normal perfusion study (n = 20) when compared with TID-negative patients with a normal perfusion study (n = 48). In addition, there was no significant difference in the incidence of major adverse cardiac events when comparing both the TID-positive patients and the TID-negative control cohort and when comparing patients who were TID-positive with normal perfusion with patients who were TID-negative with normal perfusion.
Conclusion:
The presence of TID with an otherwise normal SPECT MPI study does not translate into a greater extent of coronary artery disease as assessed by cardiac CT or increased risk for future major adverse cardiac events.
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An X-ray, or radiograph, is a non-invasive method that uses ionizing radiation to take images of internal structures. It is mainly used in cardiac imaging to examine the heart, lungs, and major blood vessels, aiming to identify abnormalities in the heart's size, shape, and position, such as heart failure, congenital defects, and vascular...