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Current computed tomography angiography for the mechanism of acute coronary syndrome and the guidance of PCI, ESC and the Japanese Circulation Society

ESC Congress Report

  • PET -CT 18-F fluoride imaging identifies unstable plaque, in comparison with pathological studies and in vivo intravascular imaging.
  • Unstable or disrupted plaques share particular morphological characteristics.
  • Patients with low-attenuation plaques and outward vessel remodelling developed an ACS (22%). 
  • The hemodynamic significance of angiographic coronary artery disease is an important parameter for therapeutic decisions.
  • The SYNTAX score is associated with outcome and is recommended for revascularization  decisions.


View the Slides from this session in ESC Congress 365

During this session new cardiac CT techniques and applications were discussed in the context of acute myocardial infarction and revascularization guidance.
 
Dr. Mark Dweck (Edinburgh, UK) discussed the use of CT-PET imaging of coronary plaque and its potential value for identification of vulnerable lesions. CT-PET imaging combines the high spatial resolution of CT with the high signal sensitivity of PET imaging. Several approaches have been explored to image vulnerable plaque. 18-F FDG PET imaging of glucose metabolism can be used to image the increased metabolism present in active plaques, but is practically limited by the high natural glucose metabolism of the myocardium. More recently 18-F fluoride imaging was demonstrated to identify unstable plaque, in comparison with pathological studies and in vivo intravascular imaging. 18-F fluoride binds to the surface of calcific deposits and has a relatively high uptake in microcalcification, which are associated with plaque activity. It represents a promising new application of a tracer that has previsoulsy been used in non-cardiac applications, and which is not affected by myocardial uptake. Trials are underway to investigate the ability of 18F fluoride imaging to predict adverse cardiovascular events.
Coronary calcification limits the diagnostic performance of CT coronary angiography because of blooming artifacts and beam hardening. Because of the enlarged appearance of the calcium on the CT images, the stenosis severity may be overestimated.

Dr. Klaus Kofoed (Copenhagen, DK) demonstrated the use of coronary subtraction for the improvement of the diagnostic performance of CT angiography. To this approach a non-enhanced CT scan (the calcium scan) is digitally subtracted from the contrast-enhanced CT angiogram. Preliminary results indicate that the lumen can be better appreciated and the lumen more accurately assessed. The accuracy of the approach will be investigated using the data of the international CORE 320 trial.   
Pathological and invasive imaging studies have demonstrated that unstable or disrupted plaques share particular morphological characteristics. There has been substantial scientific interest in non-invasive identification of rupture-prone atherosclerotic plaque to prevent acute coronary events.

Dr. Yukio Ozaki (Totoake, JP) presented the potential value of CT angiography to understand the mechanism and predict Acute Coronary Syndrome (ACS). Cardiac CT is able to reproduce several characteristics of plaque vulnerability, including plaque volume, outward vessel remodelling and low-attenuation plaque, and preliminary results suggest that these characteristics predict adverse events in patients evaluated by cardiac CT. Patients with low-attenuation plaques and outward vessel remodelling developed an ACS (22%).  
The hemodynamic significance of angiographic coronary artery disease is an important parameter for therapeutic decisions. CT angiography based estimation of the fractional flow reserve presents a new approach to determining hemodynamic coronary disease severity. Using regular CT angiograms, without adenosine administration, computational fluid dynamics are used to calculate the pressure gradient in comparison to the aorta throughout the coronary arteries.

Dr Bjarne Norgaard (Aarhus, DK) discussed FFR-CT and CT-SYNTAX scoring to select candidates for PCI, and presented the results of several large trials that demonstrated the correlation with invasive FFR and the incremental diagnostic value in comparison with CT angiography alone. The SYNTAX score, which considers various aspects of the coronary anatomy and pathology, is associated with outcome and is recommended for revascularization  decisions. The SYNTAX score can also be calculated from cardiac CT images and potentially provides an noninvasive alternative to the catheter based SYNTAX score. 

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Current computed tomography angiography for the mechanism of acute coronary syndrome and the guidance of PCI, ESC and the Japanese Circulation Society

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.