Clinical Utility of Intravascular Imaging

Although it is the tool used by most interventional cardiologists to assess the severity of coronary artery disease and guide treatment, coronary angiography has many limitations because it is a shadowgraph, depicting planar projections of the contrast-filled lumen that are often foreshortened rather than imaging the diseased vessel itself. Currently available intravascular imaging technologies include grayscale intravascular ultrasound (IVUS), optical coherence tomography (OCT) (the light analogue of IVUS), and near-infrared spectroscopy that detects lipid within the vessel wall and that has been combined with grayscale IVUS in a single catheter as the first combined imaging device. They provide tomographic or cross-sectional images of the coronary arteries that include the lumen, vessel wall, plaque burden, plaque composition and distribution, and even peri-vascular structures-information promised, but rarely provided angiographically. Extensive literature shows that these tools can be used to answer questions that occur during daily practice as well as improving patient outcomes. Is this stenosis significant? Where is the culprit lesion? What is the anatomy of an unusual or ambiguous angiographic lesion? What is the right stent size and length? What is the likelihood of distal embolization or periprocedural myocardial infarction during stent implantation? Has the intervention been optimized? Why did this stent thrombose or restenose? This review summarizes these uses of intravascular imaging as well as the outcomes data supporting their incorporation into routine clinical practice.