Direct and noninvasive visualization of the extent of coronary artery atherosclerosis is a major goal in the effort to assess coronary heart disease. Coronary artery calcium and carotid intima medial thickness are examples of surrogate markers of coronary atherosclerosis that attempt to non-invasively define the extent of coronary artery disease present. Coronary calcium in particular is a marker for coronary atherosclerotic burden but is a minor component of total plaque and is not present in early plaque. Coronary artery wall MRI is a new method to directly measure the thickness of the coronary artery wall, and is the only existing noninvasive test without ionizing radiation that can directly interrogate the coronary vasculature and provide a measure of disease burden at this early stage. Prior studies have shown increased coronary artery wall thickness is detected by MRI when no or minimal narrowing of the coronary artery lumen is present. Thus, this study proposes to assess the role of coronary artery wall thickness as a measure of early atherosclerotic disease using MRI, and 2) to determine the relationship of coronary artery wall thickness to both known risk and other noninvasive surrogate markers of atherosclerosis. This study will be performed within the context of the Multi-Ethnic Study of Atherosclerosis (MESA), an NHBLI prospective study of 6814 subjects without clinically manifest atherosclerotic disease. The underlying hypothesis of the MESA study is that the pathway from risk factors to clinical disease is through the development of subclinical disease. The MESA cohort is well characterized in terms of traditional risk factors and serologic markers for atherosclerotic disease. There is also phenotypic characterization of the cohort using carotid ultrasound, coronary calcium and MRI of the carotid and aortic wall.
The specific aims of this application are to 1) determine the relationship between known risk factors for cardiovascular disease and coronary artery wall thickness, 2) determine the relationship between coronary artery wall thickness and coronary artery calcium and carotid wall thickness and 3) measure the progression of coronary artery wall thickness over time. The combination of direct coronary artery wall thickness measurement by MRI with the existing disease markers in MESA will be an effective way to assess the relationship of these markers to early pathologic changes in the coronary arterial bed. The ability to directly define the extent of coronary atherosclerosis at an early stage should lead to an improved understanding of coronary risk factors and their impact on atherosclerosis development. ? ?
