Professor Giulio Guagliumi CIT 2010 Interview

<International Circulation>: At CIT 2010 you have a presentation of new data， new strategies and new concepts of OCT applications of coronary stent implantation. Could you give us a brief summary of your lecture on the subject of OCT?

Prof. Guagliumi: My lecture explained the current status of this innovative technology， how we can utilize it， the best indications for its usage， and what we can expect in the future. There are two major fields in which we can use this technology. One area that we can use it is first assessment in vivo in patients of human biology， especially for coronary artery disease. For the identification and characterization of plaque， OCT has a very high level of axial resolution and it is 10X more powerful than IVUS and it provides a tomographic view. This means that you scan a vessel with very high speed infrared lights and data is collected in all the different sections in a vessel in a short period of time and it sends images back in a tomographic view telling you about the measurement of the vessel as well as the location and topology of the plaque. This is the first attempt to have a higher resolution compared to IVUS. For plaques， it has the capability to measure the thickness of the cap. We know that the plaque is inside the vessel wall and the resistance of the plaque is partially linked to the thickness of the cap. When the cap becomes thinner there is an increased risk of rupture when there is an inflammatory process happening. In this case， we can measure the thickness of the cap for the first time. We are going below the 100 micron limit of IVUS and we can measure cap thicknesses below 60 microns， which is the typical thickness for caps that may rupture. The level of resolution with OCT is 10 microns， which is at least 10x the resolution level of IVUS. In addition to measuring plaque thickness， OCT has very high sensitivity for thrombus. When you have a thrombus， the technique shows the thrombus as well as angioscopy， but in a tomographic view so you can see exactly where the thrombus is located around the lumen. Using certain characteristics of the optical signal， you can differentiate white thrombus from red thrombus; the more recent thrombus compared to more organized thrombus. There is a lot of work being done， especially by Professor Akasaka’s group， on identifying the numbers and locations of plaques in multiple vessels and in multiple situations， including acute myocardial infarction， in addition to the risk in terms of profile characteristics. The second field of interest that is growing dramatically is showing response to intervention， especially stents. At the time of stent implantation you can very accurately identify the level of full apposition of the struts， measure the MLA， and multiple characteristics. Especially in follow-up， you start to have an identity over time of the vascular response of the stent. This is particularly important with DES because DES deliver drugs into the vessel wall and the vessel wall is not going to respond in a uniform way. We know that with a DES we have a longer time period until full coverage and sometimes the patient can suffer from stent thrombosis. This is a very important issue because the therapeutic approach has changed dramatically from BMS to DES. Previously， we used a double antiplatelet regimen for one month and then aspirin. Today， there is a lot of confusion and patients suffer from major complications three or four years later. There are different mechanisms， but some reasons for these problems are uncovered struts， a toxic response of the vessel to the polymers and accumulation of the drugs. There are also other issues such as new development of plaques. My group conducted many studies on the heterogeneity of the response. There are significant differences among sections of the vessel in terms of amount of tissue growing， amount of coverage， and evidence of toxic responses.