Atherosclerosis in abdominal aorta may predict adverse cardiovascular events

Interesting study from the University of Texas, using MRI to screen for atherosclerosis.

Accumulation of plaque tells us there is increased risk for peripheral vascular occlusion, stroke, and abdominal aortic aneurysms, but not all forms of cardiovascular events, including heart attacks and death from cardiovascular disease,“ he said. ”In contrast, thickening of the aortic walls is more likely to be predictive of all forms of cardiovascular disease.

This is a different approach to merely screening for risk factors of atherosclerosis, and one that is endorsed by SHAPE.

British Heart Foundation's Reflections of Research Competition

A video that we submitted to the British Heart Foundation's "Reflections of Research" competition has won in the best video category.

We made this video to highlight the variety of imaging methods that we have at our disposal to image atherosclerosis and its consequences.

Some more coverage on the Cambridge BRC website and the Addenbrooke's Hospital homepage.

Click here to view the other winning entries.

Guidelines For Assessment Of Cardiovascular Risk In Asymptomatic Adults

ACCF/AHA guidelines - nice summary of current thoughts.

Similar guidelines were published recently by the European Society of Cardiology.

CT ClinImage Cardiac 4

Figure 6  2

Images above show non-invasive cardiac imaging using CT, compared (bottom) to invasive coronary angiography - 'A'. Note the distal left main stem 'soft' plaque visible on the contrast CT - 'C', invisible on the non-contrast calcium scoring CT scan in 'B'.

Dangerous plaques are missed by calcium scoring alone in maybe 5% scans in symptomatic subjects.

Low healing rate amongst complex carotid artery plaques - a longitudinal MRI study

What surprised me the most about this elegant study was the very low rate of healing of complex plaques that had caused cerebrovascular events. We know that the risk of recurrent events is very high immediately after TIA but drops off rapidly. Presumably, even high-resolution structural imaging takes some time to reflect this change in risk.

I believe this is the first longitudinal study to address this issue in humans.

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Atherosclerotic plaque imaging - past, present, and future

Dr. Alistair Lindsay hosts a round table from the British Cardiovascular Society Conference in Manchester, on the topic of atherosclerotic plaque imaging; past, present, and future.

He is joined by:

  • Matthias Nahrendorf, Center for Systems Biology, Harvard University
  • Farouc Jaffer, Center for Molecular Imaging Research, Harvard University
  • James Rudd, Division of Cardiovascular Medicine, University of Cambridge
  • Robin Choudhury, Department of Cardiovascular Medicine, University of Oxford

Click here to listen.

See also:
Webcasts from all the sessions at the British Cardiovascular Society Conference 2012

Click here to watch.

Non-invasive imaging of atherosclerosis review in EHJ

A very comprehensive review from an eminent group of authors appeared in EHJ recently.

Non-invasive anatomic and functional imaging of vascular inflammation and unstable plaque

It covers:

  1. Pathobiology of plaque, including lipid accumulation, oxidation, inflammation, matrix breakdown, apoptosis and calcification (both macro- and micro-).

  2. Imaging techniques PET, SPECT, CT, MRI and ultrasound

There were some interesting comments on the increasing use of FDG PET imaging for detection of inflammation in atherosclerosis : -

Despite these attractions, some issues require resolution before embracing FDG uptake in this regard. Firstly, only limited prospective data correlate FDG uptake, or changes in FDG uptake, with cardiovascular events or altered rates of such complications,42 and we eagerly await the results of larger prospective cohort studies, such as the High Risk Plaque Initiative and BioImage studies."

"In this regard, nuclear agents that image hypoxia, already in use in oncology, may be
useful in imaging atherosclerosis, as hypoxic conditions may prevail in the core of lesions."

I quite agree on point 1 and keep watching this space for point 2!

Day 3 ESC

A very well attended session at the ESC today concerned novel approaches to imaging the vulnerable plaque.

We heard from Zahi Fayad (New York), Jagat Narula (Orange, Ca) and Beat Kaufmann from Basel in Switzerland. I gave an over-view of vascular PET imaging, both with FDG and novel targeted ligands against plaque macrophages.

The session tried to communicate not only the state of play in 2010, but also to predict what may be around the corner for imaging. There seems to be a move towards more platform integration, with the appearance of combined PET/MR hardware. This will allow high sensitivity/high resolution imaging of the artery wall. I guess this will have large impact in brain imaging and likely also in cardiology for myocardial imaging.

For CT, as well as a move to lower radiation dose, Zahi Fayad talked about multi-color CT, something that holds great promise in separating out the various plaque elements, to a much greater extent than currently feasible with single energy imaging with iodine contrast agents. This work was recently published in Radiology (Cormode D et al - see image below).

We also heard a great review of ultrasound imaging of vulnerable plaque, using targeted microbubbles against selectins and adhesion molecules. Whilst very exciting, the field is confined right now to small animal models of disease, and to epitopes expressed on endothelial cells. But there is promise of eventual human translation.

What caught your eye in Stockholm today?

Picking the plaques that go pop

Another exciting day in Barcelona. The highlight for me was a session dedicated to imaging of atherosclerosis, both from within the coronary arteries and non-invasively. My take-home message was that whilst we have many ways of quantifying the extent, structure and functional state of atherosclerosis in the coronary arteries and elsewhere, we are still in desperate need of prospective trials in this area. It is all very well to image atheroma; as clinicians we need to know more - we need to know which patients will suffer CV events in the future. We can choose from risk scores, such as Framingham. We can use circulating biomarkers - CRP, lipids and many others. And finally imaging of atherosclerosis. How to bring them all together?

Thankfully, there are a couple of very interesting trials underway. The first is the High Risk Plaque BioImage study, co-ordinated by BG Medicine in USA. This large, prospective, event-driven study in asymptomatic subjects has already recruited over 5000 patients for imaging (CT, MRI, FDG PET, IMT, calcium score) plus biomarkers. Over the next 3 years, CV events will occur in these patients; as a result we will discover the true 'predictability' of these modalities.

The second trial of huge interest is the PROSPECT study, due to be reported at TCT in San Francisco in late September. This focusses on invasive plaque assessment with coronary angiography, palpography and IVUS-VH and again attempts to predict events on the basis of imaging and circulating biomarkers over a 3 year period.

Let us know in the comments your thoughts on invasive and non-invasive plaque imaging.