The role of intravascular ultrasound in the determination of progression and regression of coronary artery disease.

New imaging techniques have been used to examine surrogate markers of atherosclerotic burden to determine the effects of pharmacologic intervention. In this review, we discuss the role of intravascular ultrasound (IVUS) in the determination of progression and regression of coronary artery disease. Several methodologic issues are discussed (selection of segments to analyze, measurement error, high drop out rate, and optimal IVUS variables). Usefulness of new IVUS-derived variables (plaque composition by radiofrequency analysis, deformability by palpography, and endothelial shear stress by three-dimensional coronary anatomy reconstructed from IVUS and angiography) will be determined. Based on comparisons between IVUS and clinical studies, IVUS variables seem to be a valid surrogate in studies using atorvastatin in patients with dyslipidemia. It remains unclear whether IVUS variables are valid surrogates for other drugs/diseases. As such, further studies are needed to determine whether IVUS can serve as an efficient surrogate for clinical events in coronary disease trials.