Noncalcified Atherosclerotic Plaque Burden at Coronary CT Angiography: A Better Predictor of Ischemia at Stress Myocardial Perfusion Imaging Than Calcium Score and Stenosis Severity
July 21st, 2009 Posted by: admin
OBJECTIVE. The purpose of this study was to examine the relation
between the coronary CT angiographic findings of calcified and noncalcified
plaque burden and stenosis severity and the myocardial perfusion imaging
finding of ischemia.
MATERIALS AND METHODS. Seventy-two patients (41 men, 31 women; mean
age, 56 years) underwent coronary CT angiography and stress-rest SPECT
myocardial perfusion imaging. Calcium scoring was performed. Coronary CT
angiograms were analyzed for stenosis and noncalcified or mixed plaque. A
plaque analysis tool was used to calculate the volume of noncalcified plaque
components. SPECT images were analyzed for perfusion defects. Data were
analyzed per patient and per vessel.
RESULTS. A total of 53 purely noncalcified, 50 mixed, and 201 purely
calcified plaques were detected. Forty-five stenoses were rated ≥ 50%, 19
of those being ≥ 70%. Myocardial perfusion imaging depicted perfusion
defects in 37 vessels (13%) in 24 patients (18 reversible, 19 fixed defects).
Vessels with ≥ 50% stenosis had significantly (p = 0.0009) more
perfusion defects in their supplied territories (11 with, 22 without perfusion
defects) than did vessels without significant lesions (26 with, 229 without
perfusion defects). In vessel-based analysis, the sensitivity of coronary CT
angiography in prediction of any perfusion defect on myocardial perfusion
images was 30% with 91% specificity, 33% positive predictive value, and 90%
negative predictive value. Between vessels with and those without perfusion
defects, there was no significant difference in Agatston or calcium volume
score (p = 0.25), but there was a significant difference in
noncalcified plaque volume (44 ± 77 vs 19 ± 58 mm3;
p = 0.03). Multiple stepwise regression analysis showed noncalcified
plaque volume was the only significant predictor of ischemia (p =
0.01).
CONCLUSION. At coronary CT angiography, noncalcified plaque burden
is a better predictor of the finding of myocardial ischemia at stress
myocardial perfusion imaging than are calcium score and degree of
stenosis.
