Coronary intravascular ultrasound: implications for understanding the development and potential regression of atherosclerosis

The incremental value of intravascular ultrasound (IVUS), compared with angiographic analysis of coronary atherosclerosis, originates principally from 2 key features—its tomographic perspective and the ability to image coronary atheroma directly. Whereas angiography depicts the cross-sectional coronary anatomy as a planar silhouette of the lumen, ultrasound directly images the atheroma within the vessel wall, allowing measurement of atheroma size, distribution, and to some extent, composition. Although angiography remains the principal method to assess the extent of coronary atherosclerosis and to guide percutaneous coronary interventions, IVUS is rapidly altering conventional paradigms in the diagnosis and therapy of coronary artery disease. Thus, IVUS has become a vital adjunctive imaging modality for the aggressive coronary interventional cardiologist. As such, ultrasound has earned a role as a viable complementary technique relative to angiography, rather than an alternative to conventional angiographic methods. This article reviews the rationale, technical advantages and limitations, and interpretation of intravascular ultrasonography from the perspective of the general and invasive cardiologist. We emphasize the impact that IVUS studies have had on our understanding of the atherosclerotic coronary artery disease process, because these findings have important implications for all cardiologists. We then review several trials that are currently using intravascular ultrasonography for the study of coronary artery disease regression.