Optical Coherence Tomography as a Tool for Percutaneous Coronary Interventions Larry J. Diaz-Sandoval, MD, Brett E. Bouma, PhD, Guillermo J. Tearney, MD, PhD, and Ik-Kyung Jang, * MD This study was performed to demonstrate the ability of intravascular optical coherence tomography (OCT) to identify characteristic vascular responses to percutaneous cor- onary interventions (PCI). OCT provides cross-sectional images of tissue in situ at approximately 10 mm, rendering detailed structural information. Intravascular ultra- sound and OCT images were obtained from 10 patients before and after PCI. Images were evaluated to identify balloon-induced dissections/disruptions, thrombus, cutting balloon-induced vascular changes, tissue protrusion, stent apposition and symmetry, and intimal hyperplasia. The disrupted intima, intraluminal thrombus, depth of balloon- induced dissections, cutting balloon cuts, tissue prolapse, underdeployed struts, and intimal hyperplasia were all noticed with OCT. This is the first report of the use of OCT to identify in vivo human intracoronary pathology after PCI. ' 2005 Wiley-Liss, Inc. Key words: tomography; catheters; imaging; plaque; coronary intervention INTRODUCTION Atherosclerosis is the main pathophysiologic process underlying ischemic heart disease, which remains the leading cause of morbidity and mortality in the United States [1]. Revascularization techniques are currently targeted to angiographically significant lesions, although it is currently accepted that most myocardial infarctions are secondary to rupture and erosion of a subset of angiographically modest atherosclerotic plaques [2–6] that have been termed ‘‘vulnerable.’’ Autopsy studies have identified features that are common to plaques that are prone to rupture, such as the presence of a thin fibrous cap (< 65 mm), a large lipid-rich core, and activated macrophages [7–11]. Although intravascular ultrasound (IVUS) has been routinely used in interven- tional cardiology, the resolution (100 mm) limits its use for plaque characterization. Intravascular optical coher- ence tomography (OCT) provides cross-sectional images of tissue with a resolution of 10 mm, allowing high- resolution visualization of atherosclerotic plaque mor- phology. This new imaging modality may be useful not only in detecting different types of intravascular pathol- ogy such as plaque types (lipid-rich, fibrous, and calcific plaque) but also in visualizing detailed structural changes such as ulcerated plaques, intraluminal throm- bus, tissue prolapse, and intimal hyperplasia in cases of in-stent restenosis [2,7,12,13]. The aim of this study was to test the ability of OCT to identify characteristic vascular responses to coronary interventions, as well as the extensive human intravas- cular pathological features corresponding to different disease states. MATERIALS AND METHODS Ten patients (eight men and two women; mean age, 59) undergoing percutaneous coronary intervention (PCI) for unstable angina and/or myocardial infarction were enrolled in the study after written informed con- sent was obtained. The institutional review board approved the study protocol. Coronary interventions were performed according to standard practice using a 0.014@ (0.36 mm) guidewire through a 6 or 7 Fr guiding catheter. IVUS and OCT imaging were performed before and after the coronary intervention. The IVUS catheters used in this study incorporated a single 30 or 40 MHz transducer within Cardiology Division and Cardiovascular Clinical Research, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts Grant sponsor: Guidant (Santa Clara, CA). *Correspondence to: Dr. Ik-Kyung Jang, Cardiology Division, Gray/ Bigelow 800, Mailstop 843, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114. E-mail: ijang@partners.org Received 15 October 2004; Revision accepted 26 January 2005 DOI 10.1002/ccd.20340 Published online 26 May 2005 in Wiley InterScience (www.interscience. wiley.com). ' 2005 Wiley-Liss, Inc. Catheterization and Cardiovascular Interventions 65:492–496 (2005)