Cath Lab Digest - November 2007 - (Page 22)

22 PHYSIOLOGIC MEASUREMENT NOVEMBER 2007 The Clinical and Economic Impact of Measuring Fractional Flow Reserve proportion of the time, the severity of one lesion versus the other is not obvious with visual estimation alone. When I am not comfortable in determining whether or not the stenosis is hemodynamically significant, I resort to a pressure guidewire. It adds about 10 minutes to the procedure. We use the PressureWire (Radi Medical Systems, Wilmington, MA). The DEFER trial, which was presented earlier this year with positive results, looked at elective PCI patients with stable chest pain and one lesion. Yet all types of complex, multi-vessel disease patients are seen in cath labs daily. Is it possible to extrapolate the trial data for more complex disease? Yes, and it is the same story with any new device or technology. The benefit of clinical trials is that they allow for the introduction of new technology that does something good for the patient. We use clinical trials to apply the technology to the general population. If we are going to wait for every subset of patients to be studied in a clinical trial, we won’t be able to take good care of our patients. It is not possible to study all types of patients by the use of randomized clinical trials and therefore it is impossible for us to get an answer for every subset of patients. In clinical practice, we have to use our judgment to generalize when possible, knowing that there are pitfalls and that the certain population we are generalizing to may not fall into this group that was studied. This is not something new. You have to use your clinical judgment as to when to use a new technology, like a pressure guidewire, in a subset of patients that has not been studied. So, I have been generalizing, like everybody, like with any device, and with success. I get a lot of input from using this technology to make better decisions. It has been very helpful. Pressure guidewires are an excellent addition to our diagnostic armamentarium. I think they need to be used more often than they are at present, because the interventionalist is then equipped to make the right decision at the right time without delaying patient care. Could you share a recent complex case and describe how FFR measurement was incorporated? I actually had a patient last week, in his mid-50’s and diabetic. Two years ago, I placed stents in his right coronary artery and left circumflex, and he did well, but recently developed typical angina. A stress thallium showed antero-lateral and inferior ischemia. I proceeded with coronary angiography and to my surprise, the stents and the left anterior descending artery were fine. The only thing I could see was a tubular lesion in the left main. It did not strike me as severe. The left main was a long vessel and in its mid-portion there was a long area of some narrowing, but it did not look bad at all. I would estimate it to be in the 40% range, at worst. I could not find any other lesions to explain the typical symptoms of angina as well as the abnormalities in the stress thallium. I decided to quickly measure FFR by using the pressure guidewire. The patient had a resting gradient of about 20mm of mercury without adenosine, and with IV adenosine, his fractional flow reserve was 0.68, which is one of the worst I have ever seen (remember that a FFR of < 0.75 equals a functionally significant stenosis). This patient ended up getting open-heart surgery the next day, and he is about to go home today. Without having measured FFR, what course might you have chosen? We would have scratched our heads a lot, and I probably would not have sent him to bypass surgery. I would have tried him on medical therapy, and if I’m lucky and he’s lucky, he wouldn’t drop dead on medical therapy because of left main disease. Probably medical therapy would not have worked and I would have ended up cathing him again, and eventually, would have sent him to surgery. Ultimately, I expedited good care for this patient by using a pressure guidewire. F ractional flow reserve (FFR) is defined as the ratio of maximum flow in the presence of a stenosis to normal maximum flow. It is a lesion-specific index of stenosis severity that can be calculated by simultaneous measurement of mean arterial, distal coronary, and central venous pressure (Pa, Pd, and Pv, respectively) by a pressure guidewire during pharmacological vasodilation. 1 A functionally significant stenosis is defined by a FFR measurement of less than (<) 0.75. DEFER, a five-year, 325-patient prospective randomized trial presented in late May 2007 in The Journal of the American College of Cardiology,2 concluded that stenting any lesion with an FFR of 0.75 or greater (≥ 0.75) does not relieve any symptoms or prevent future cardiac events. Cath Lab Digest talked with Fadi Matar, MD, of Tampa General Hospital in Tampa, Florida, about his five-year experience with this technology. What are the criteria you utilize to determine whether or not to use a pressure guidewire in a particular case? Visual estimation of the stenosis. As you know, patients with coronary artery disease don’t necessarily have one area that is severe. Typically, it’s diffuse disease involving multiple areas in the coronary tree. A good Figure 1. Angiographically ambiguous left main lesion.

Table of Contents Feed for the Digital Edition of Cath Lab Digest - November 2007

Henry Ford Heart and Vascular Institute Treating Patients with Complex Vascular Disease with a Multi-Disciplinary Approach Improving Patient Compliance with Antiplatelet Medications Clinical Editor’s Corner Cath Lab Nurse/Tech Vascular Access and Closure Using the StarClose® Device The Clinical and Economic Impact of Measuring Fractional Flow Reserve FFR and Choosing an Optimal Revascularization Strategy Finally! The New Registered Cardiac Electrophysiology Specialist (RCES) Credential Use of a Mobile Lab to ‘Test the Waters’ at a Rural Hospital Remembering a Cardiac Cath Lab History ACVP• Membership Page What Do You Think? The Ten-Minute Interview with… Ernie Livingston, RN, BSN SICP* Chapter Updates Who’s in Charge? Working to Eliminate Bottlenecks: Florida Hospital’s Cardiac Cath Lab Achieves Greater Efficiency and Higher Satisfaction Preserving Left Ventricular Function during Percutaneous Coronary Intervention Ask the Clinical Instructor: A Q&A Column for Those New to the Cath Lab Making the Most of Your First Impression: Interviewing Tips and Techniques CEU Education Center Clinical & Industry News Meetings Calendar

Cath Lab Digest - November 2007

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