Cath Lab Digest - March 2008 - (Page 42)

42 CLINICAL UPDATE MARCH 2008 Intravascular Ultrasound in the Cath Lab: A powerful — and underutilized — tool to improve patient outcomes Cath Lab Digest talks with Michael C. Foster, MD, FACC, South Carolina Heart Center, Columbia, South Carolina; Medical Director of the Cardiac Catheterization Laboratory at Providence Hospital, Columbia, South Carolina became interested in DES expansion very early on, within a month or two of starting to deploy these stents. We saw some thrombosis issues and began to start using IVUS on DES patients to see if we could learn something that might explain these events. What we immediately saw is that even though the stents look good angiographically, IVUS showed many of the stents were underexpanded and in some cases, the struts weren’t properly apposed. I discovered you have to work hard with non-compliant balloons at high pressures to properly deploy DES. Recent work by Dr. Lowell Satler and others at the Washington Heart Center indicate this to be true. Interestingly, in our experience, once we started looking at DES with IVUS and working a little harder to get them expanded, we quit seeing the thrombosis issues. We haven’t published that data, but it certainly was anecdotally evident in our own practice. I hope that in the future we will see some data that will verify the value of using IVUS in DES procedures. The ADOPT DES stent registry, with Dr. Gregg Stone and Dr. Bruce Brodie as the national co-principal investigators, is just getting started and will be looking at this very issue. Will any of the next-generation DES perhaps mitigate this problem, with their thinner-strut stents? I am hoping that will be the case. I have had a limited experience with newer generation stents as an investigator in a Boston Scientific-sponsored trial called PERSEUS (A Prospective Evaluation in a Randomized Trial of the Safety and Efficacy of the Use of the Taxus® Element™ PaclitaxelEluting Coronary Stent System for the Treatment of De Novo Coronary Artery Lesions), with their third-generation stent, which is exceedingly thin and deliverable. Hopefully those Is there enough awareness in the interventional community about intravascular ultrasound (IVUS)? From my perspective, the answer is clearly no. IVUS is a powerful tool that is not being properly utilized. It is under-considered and too many excuses are given for not using it. Have the issues with drug-eluting stents and stent thrombosis been a wake-up call? It has been a wake-up call. Of course, early on when this issue came up, all the focus was on the stent technology itself. People talked about how maybe we shouldn’t be putting drugs on stents. There was not much discussion about how the issue is perhaps not the stent technology, but in part due to how we are deploying these stents. From my perspective, drugeluting stents (DES) clearly require more work to fully expand than the thinner bare-metal stents. That’s just common sense. DES have thicker strut material, and the struts are coated with a polymer, further restricting their ability to expand, and then of course, there is a deliberately delayed healing process with the medication. I interventionalists deploying DES without the benefit of IVUS and who are just using moderate pressures with delivery balloons will see that the next-generation DES are being better expanded. However, I don’t think we have seen enough data on the newer stents yet. Obviously the trials that get these stents approved by the FDA look good, but most of them are done with relatively simple lesions and in a relatively small number of patients. You don’t have the statistical power to determine very minor differences of rare events like stent thrombosis. As the experience progresses and people use the next-generation DES in more difficult anatomy, I think time will disclose those answers. What are some of the patient or procedure characteristics that should prod a physician to use IVUS? Let me disclose right at the beginning that in my personal practice, my IVUS use is at about 90%. If I am going to put in a DES, I want to be very certain in my mind that I have done my best to expand it. Do I believe every patient who receives a DES has to have IVUS? I think I could make an argument for it, but I probably don’t have the data at this point to make that determination. There are at least three scenarios which clearly ought to include the use of IVUS. First, any patient with instent restenosis, because you don’t know the cause of in-stent restenosis by angiography, you only know the vessel is narrowed. In about a third of the vessels I see with in-stent restenosis, the stenosis isn’t from tissue growth or neo-intimal hyperplasia, it is a focally underexpanded stent. These patients don’t need a new DES; what they need is that stent to be properly expanded. I have seen many cases where there is absolutely no neointimal tissue at all. Obviously if there is extensive, diffuse neo-intimal growth that is the cause of that instent restenosis, a DES or a different DES than what they received before is probably the answer. So in-stent restenosis is one scenario that cries out for IVUS. Second, for any angiogram you are having difficulty understanding, whether you are uncertain if there is thrombus, or you are just having difficulty assessing the vessel size or the severity of the lesion, I would advocate IVUS. You are likely to get a definitive answer with IVUS and I would say parenthetically that virtually all angiographers, no matter how experienced, routinely underestimate the size of vessels when they rely on angiography alone. It’s surprising how often you are thinking of putting in a 2.75 or 3.0 stent, then you do actual measurements and it’s a 3.5 vessel. Most studies show that most angiographers underestimate the vessel size, by at least 0.5 mm or even up to .75 mm. For any unanswered question angiographically, I would advocate IVUS. Third, I’d advocate IVUS for complicated lesion subsets. For example, bifurcation lesions, ostial lesions, left

Table of Contents Feed for the Digital Edition of Cath Lab Digest - March 2008

Cath Lab Digest - March 2008 Are You Being Paid Fair Market Value in 2008? A Cardiac Cath Lab Professionals Survey by Cath Lab Digest and the Society of Invasive Cardiovascular Professionals Saint Joseph’s Hospital Invasive Imaging Tools for Optimizing Coronary Stent Deployment Contents Clinical Editor’s Corner A Workflow Revolution in Cath Lab Reporting Advantages of a New Digital Lab at Baystate Medical Center Cardiac Computed Tomography: What Does it Mean for the Cath Lab? The Latest in Cardiac Magnetic Resonance Imaging (MRI) Cellular Cardiomyoplasty and Cardiac Regeneration Intravascular Ultrasound in the Cath Lab: A Powerful — and Underutilized — Tool to Improve Patient Outcomes The Stentplus™ Patient Success Program Cardiac Cath Lab Clutter — or, Spring into Action! Groin Bleeds and Other Hemorrhagic Complications of Cardiac Catheterization: A List of Relevant Issues Ask the Clinical Instructor: A Q&A Column for Those New to the Cath Lab What Do You Think? Experience with a New Guidewire: The Terumo Runthrough NS The Ostial Pro™ Stent Positioning System: Perfecting Aorto-Ostial Stent Placement Precious Minutes The Ten-Minute Interview with…Mark Bowles, BSN, CCRN Vascular Care in the Cath Lab: Planning a Smooth Transition Cath Laughs CMS 2008 OPPS Final Rule Review An Extensive Set of Review Courses for the CCI Basic Science, Non-Invasive Echocardiography and Vascular, and ARDMS Ultrasound Exams Meetings Calendar CEU Education Center Clinical & Industry News STEMI Interventions Classifieds Advertisers Index

Cath Lab Digest - March 2008

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