Coronary Plaque Characteristics on CT Angiography Predict Post-Catheterization Injury
Last Updated: 2010-01-20 10:00:29 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Using CT angiography to determine plaque characteristics before electively implanting a coronary artery stent may help gauge the risk of injury or myocardial infarction (MI), according to a report from Japan.
The clinicians there found that low-attenuation plaque was an independent predictor of post-procedural myocardial injury.
Low-attenuation plaque "may represent lipid-rich plaque," which may be more likely to embolize during stent placement, lead author Dr. Tadayuki Uetani of Chubu Rosai Hospital in Nagoya told Reuters Health by email.
In 189 consecutive patients scheduled for stent implantation in the next two weeks, Dr. Uetani and colleagues used 64-slice multi-detector CT angiography to characterize target lesions. Low-attenuation plaque was defined as having a CT density of < 50 Hounsfield units (HU); moderate-attenuation plaque as 50 to 150 HU; and high-attenuation plaque as greater than >500 HU. (The density of the dye-filled lumen was 151 to 500 HU).
After coronary intervention, troponin T levels rose (indicating myocardial injury) in 59 patients (31.2%), the researchers report in the January issue of JACC: Cardiovascular Imaging.
According to their paper, the group with post-procedural myocardial injury had a significantly larger mean volume of low-attenuation plaque (87.9 vs 47.4 mm3, p < 0.01) than the group without injury.
"The association was striking -- in patients with troponin increase, the average volume of low-(attenuation) plaque was twice as high as in patients without troponin elevation," note the authors of a related commentary.
On multivariate analysis, the volume of low-attenuation plaque was an independent predictor of troponin T elevation. Both the volume of low-attenuation plaque and its fraction correlated positively with biomarkers.
The injury group also had a larger volume of moderate-attenuation plaque compared to the no-injury group (111.6 vs 89.8 mm3, p < 0.05). The moderate-attenuation plaque volume correlated positively with biomarkers, but the biomarkers were negatively correlated with the moderate-attenuation plaque fraction.
This suggests to the researchers that moderate-attenuation plaque volume "does not essentially contribute to a post-procedural elevation of cardiac biomarkers." However, in multivariate analysis, lower moderate-attenuation plaque fraction was an independent predictor of post-procedural myocardial injury.
In comments to Reuters Health, Dr. Uetani noted that embolic complications after coronary stent implantation are "a major roadblock" to good clinical outcomes.
"Evaluation of coronary plaque characteristics of target lesion (stenosis) by multislice CT may provide useful information to predict risk of embolic complication after stent implantation," the investigator concluded.
Editorialists Drs. Stephan Achenbach and Josef Ludwig of the University of Erlangen, Germany, point out that plaque quantification and characterization by CT is "by no means trivial." It requires "pristine image quality." They note that Dr. Uetani's team had to exclude 11 data sets due to poor image quality.
Even so, several recent trials have demonstrated a "stunning ability of CT angiography to analyze coronary atherosclerotic plaque in selected patients," they add.
"The technical development of CT imaging continues at an astounding pace," Drs. Achenbach and Ludwig write, "and although many problems remain to be solved, there is a good reason to believe that CT angiogram will become a better coronary angiogram in the future."
J Am Coll Cardiol Img 2010;3:19-30.
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