The Importance of Non-Coronary Atherosclerosis

Coronary atherosclerosis leading to coronary heart disease (CHD) is now responsible for the largest burden of morbid and mortal disease in developed countries, and this is increasing so in developing countries around the world. It is now well recognized that computed tomography (CT) scans can quantitatively assess coronary artery calcium (CAC), a direct marker of coronary atherosclerosis, and CAC can substantially aid in risk prediction of both CHD and other cardiovascular disease (CVD) outcomes. Of course, this might be expected since CAC is actually a direct measure of coronary atherosclerosis, as opposed to a risk factor for CHD such as cigarette smoking or dyslipidemia. Atherosclerosis is a generalized disease and as such also affects other arterial beds throughout the body. This observation raises the question as to whether measurement of atherosclerosis outside of the coronary arteries is of value in risk prediction or disease prognosis for CHD or CVD. Extensive research has shown that the answer is yes; that is, selected measurements of non-coronary atherosclerosis provide incremental and independent information beyond both standardized risk scores employing risk factors, as well as beyond measurement of CAC. Thus, measurements of non-coronary atherosclerosis, both subclinical and clinical, can aid in the prediction of, and determining prognosis for, CHD as well as other CVD events. The epidemiologic and clinical value of non-coronary atherosclerosis will be illustrated with data from research into four selected non-coronary atherosclerosis measures. These measures are the ankle-brachial index (ABI), which is the ratio of the systolic blood pressure at the ankle to that in the arm; subclavian stenosis (SS), which is determined by a significant systolic blood pressure difference between the left and right arms; renal artery calcification (RAC) assessed by CT scan, and abdominal aortic calcification (AAC) assessed by CT scan. Data to be presented come from both US and international studies, and will address the significance of these four measure both in persons without known CVD and in persons with a clinical diagnosis of CVD.