The Australian Atherosclerosis Society (AAS), formed in 1974 and incorporated in 1986, promotes, at a national level, the advancement of science, research and teaching in the field of atherosclerosis. The AAS endeavours to achieve these objectives by promoting the exchange of existing knowledge; encouraging new research ventures and interdisciplinary approaches; and fostering the dissemination of knowledge by organising national and international scientific meetings. Membership is open to researchers in the field of atherosclerosis and cardiovascular disease. Membership to the AAS automatically entitles membership of the International Atherosclerosis Society.

President's Report
Researchers in the field of atherosclerosis will be well aware of the difficulties in conveying abstract concepts such as molecular mechanisms. In the era of Powerpoint presentations there is increasing reliance on visual communication. This also applies to the task of cardiovascular risk assessment. Much of our research is likely to be translated into so-called “biomarkers” that may assist with the identification of high-risk individuals. Recent advances in the field of non-invasive imaging of blood vessels have created a situation in which biomarkers will complement and compete with imaging techniques in the clinical arena. This newsletter item is designed to provide some background to these developments.

The first point to make is that the invasive research technique known as intravascular ultrasound (IVUS) has demonstrated the shortcomings of the “gold standard” imaging technique – coronary angiography. Coronary angiography is limited to identification of problems in the artery lumen, whereas IVUS has demonstrated atheromatous disease in the artery wall which is not evident on angiography, and which is often very extensive. Both these methods are considered invasive because they involve arterial puncture and instrumentation of the coronary arteries. CT technology now allows visualisation of the coronary artery lumen at a quality level that is nearly equal to coronary angiography, but in which x-ray contrast dye is injected into a peripheral vein and the need for arterial puncture and instrumentation of the coronary arteries is avoided. The small risks of kidney damage due to x-ray contrast and accumulated exposure to radiation persist, but the technique is rapidly finding application in the Emergency Department assessment of chest pain for the diagnosis of acute coronary syndrome.

Although CT coronary angiography is mainly designed to show luminal disease, images obtained by CT without the use of contrast media are able to detect microcalcification of the walls of coronary arteries. This implies some degree of atheromatous coronary artery disease. It has stimulated research into similarities between tissue calcification in the artery wall and processes involved in bone metabolism. Coronary calcium scores can be obtained with less risk and less radiation. They cannot be used to assess coronary disease in detail, but a low score is associated with a low risk of future CVD events. Based on these attributes, it may have a role in CVD risk assessment. Coronary calcium score is unrelated to inflammatory markers and is not thought to provide useful information about plaque composition.

CT investigations can accommodate the motion of the heart by pulsing or gating the data acquisition and instructing the patient to hold their breath. Beta-blockers may be given to slow the heart. Overlying bony structures do not interfere with the process. MRI is also able to acquire images despite overlying ribs and sternum, but its spatial resolution is likely to remain inadequate for the next decade. Doppler ultrasound is capable of imaging both lumen and vessel wall, but coronary arteries are too small and mobile to allow effective imaging. Larger superficial arteries are ideal for ultrasound imaging, which is extensively used in peripheral vascular disease and extracranial cerebrovascular disease. Ultrasound also provides the detection mechanism for structural studies of vascular status, such as intimal medial thickness, and functional studies of vascular status, such as flow-mediated vascular reactivity.

David Sullivan