Dr. Stephen Richard Underwood,
Imaging techniques have increasing prominence, particularly with the ESC guidance on stable coronary artery disease (SCAD) released at this conference. Stress functional imaging is now the preferred first test for diagnosis in patients presenting with chest pain and an intermediate likelihood (15-85%) of underlying obstructive disease. In this session, four well known cardiac imagers presented the role of anatomical and functional coronary imaging. It was a balanced session that featured CT coronary angiography (CTCA), myocardial perfusion scintigraphy (MPS), stress echocardiography (sEcho) and cardiac magnetic resonance (CMR) and recognised the strengths and weaknesses of each. Danilo Neglia from Pisa reviewed the SCAD guidance briefly and the distinction between coronary anatomy and function for diagnosis and for assessing prognosis in SCAD. He presented the findings of EVINCI, which is a multicentre European study of stress perfusion imaging, wall motion imaging and CTCA for the diagnosis of SCAD using invasive coronary angiography as the standard. Not surprisingly, CTCA performed best in predicting the anatomical standard but perfusion imaging was accurate, more so with good quality images. Wall motion imaging by either sEcho or CMR was also accurate but it had surprisingly low sensitivity, possibly related to vasodilator stress used in a number of cases. However, with the recognition of the greater importance of managing functional rather than anatomical abnormalities in SCAD, the findings do not necessarily translate into a greater need for CTCA. Philipp Kaufmann from Zurich emphasised that anatomical and functional abnormalities were two faces of a single disease and that the role of functional imaging was mainly in intermediate stenoses since it was often possible to guess functional significance at the extremes of anatomical abnormality. He reminded us that MPS and sEcho were the only techniques with a class 1 recommendation in the 2010 ESC revascularisation guidelines but that may change as experience with CMR improves. He also described the synergistic value of combined assessment of anatomy and function using SPECT-CT techniques and argued that, in an ideal world, we would use combined assessment in all cases. Dr Rincon from Madrid discussed the evolving technique of perfusion echocardiography. Ultrasound contrast is commonly used for better endocardial definition in wall motion imaging and it can also be used to assess perfusion from the rate of replenishment of myocardial contrast after destruction by high energy ultrasound. A recent multicentre study has described good accuracy for the technique although other studies have more variable results and a recent JACC editorial reminded us of the Simon & Garfunkel lyrics, “Still waiting after all these years”. With increasing emphasis on assessing ischaemic burden in reaching management decisions, there is still some work to be done before quantitative measurements can be used clinically. Eike Nagel from London described the many ways that CMR can be used to assess ventricular and coronary anatomy and function. Perfusion CMR in particular has similar accuracy to the other imaging techniques with the advantages of good resolution. Although previously restricted to three short axis slices, 3D techniques are now available and the quantification of perfusion is now “beginning to work”. Another area of interest is the many areas of scarring detectable in patients without known infarction, since this appears to have prognostic value, although further studies would be needed before knowing whether such areas could be described as infarction. The session was well attended with discussion from the audience throughout and we look forward to hearing more as cardiac imaging matures further and the new generation of “multimodality imagers” uses the techniques to answer important and clinically relevant questions for our patients.
Anatomical and functional imaging strategies in chronic coronary artery disease
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