October 15, 2008

October 15, 2008 (Washington, DC) — The routine measurement of fractional flow reserve (FFR) during angioplasty in patients with multivessel disease significantly improves clinical outcomes when compared with traditional angiography-guided treatment, a new study has shown. Investigators report that FFR-guided PCI reduced the risk of death, MI, or repeat revascularization by 30% and death or MI by 35%, compared with the current practice of using angiography to guide stenting decisions.

"If you have a lesion that isn't causing ischemia, the intrinsic risk of the stenosis is very low, lower than the risk of placing the stent," said lead investigator Dr Nico Pijls (Catharina Hospital, Eindhoven, the Netherlands). Because interventionalists can't discriminate by angiogram which lesions are causing ischemia, "we place stents everywhere, and the benefits of placing the stent in the right position is countered by the damage we do by placing stents where it is not necessary."

Presenting the results of the Fractional Flow Reserve versus Angiography for Guiding PCI in Patients with Multivessel Coronary Artery Disease (FAME) study during the late-breaking clinical-trials session here at the TCT 2008 meeting, Pijls said he sees "no downside" to using FFR in PCI and that its use is increasing each year. "To make a new method be used in every cath lab, you need to have convincing data," said Pijls. "These data really show that FFR should be an integral part of every interventional procedure."

Commenting on the FAME study during the session, Dr Carlo Di Mario (Royal Brompton Hospital, London, UK) praised the investigators, telling the audience it was not easy to find flaws with the study. He called on cardiologists to stop telling patients such things as "You just never know," "It might progress," or "We're doing one anyway," when confronted with nonischemic vessels in a patient with multivessel disease.

"Let's forget the nonsense that we tell the patients on the table just to complete the work," said "We need to start using a scientific, evidence-based approach in multivessel disease, and this is one of the rare opportunities in medicine to reduce costs while at the same time optimize clinical outcomes."

Dr William Boden (Buffalo General Hospital, NY), who was not part of the FAME study, told heartwire that the results show that a physiologic assessment of stenosis is much better than what the eye can detect.

"There are some arteries that don't look that narrow, which you can avoid," he said. "Conversely, there are other borderline lesions that turn out to be functionally significant because there is a gradient with FFR. This is important, because it will help to really streamline practice, to help avoid unnecessary PCI in some vessels that shouldn't be fixed. It will also selectively target the really diseased vessels that would benefit from PCI."

Collateral Damage by Stenting Nonischemic Lesions

Myocardial FFR is an index of the functional severity of a coronary stenosis calculated from pressure measurements made during coronary angiography. It is used to measure the physiological impact of the stenosis on the myocardium--specifically, the ischemic effects of the stenosis on the heart.

Speaking during a morning press conference, Pijls said that stenting nonischemic stenoses has no benefit compared with medical therapy only and that stenting of ischemia-related stenoses improves symptoms and clinical outcomes. Noninvasive tests are unreliable in multivessel disease, and coronary angiography often results in interventionalists underestimating and overestimating the severity of functional stenosis.

In this analysis, investigators randomized 1005 patients with multivessel disease to angiography- or FFR-guided PCI. Patients were required to have stenoses >50% inat least two of the three major coronary arteries. For those randomized to the FFR-treatment arm, lesions with FFR <0.80 received a drug-eluting stent, while those with an FFR >0.80 were not stented.

At one year, patients who underwent coronary stenting with a drug-eluting stent guided by the FFR had significantly lower rates of death, MI, CABG surgery, or repeat PCI--the primary end point--compared with those who underwent angiography-guided PCI. Using the FFR to identify ischemic lesions also reduced the risk of death or MI by approximately 35% compared with those treated by traditional angiography-guided PCI.

FAME: Adverse Events at One Year

End point Angiography-guided PCI, n=496 (%) FFR-guided PCI, n=509 (%) p
Death, MI, CABG, or repeat PCI 18.4 13.2 0.02
Death 3.0 1.8 0.19
Death or MI 11.1 7.3 0.04
CABG or repeat PCI 9.5 6.5 0.08

Pijls said the procedure time with the two approaches was equivalent. Overall, the researchers identified 63% of lesions as having an FFR <0.80, meaning that one-third of the lesions identified during the procedure were not stented but would have been had only the angiogram been used to identify stenosis. The use of FFR also significantly reduced the financial burden of PCI, cutting the costs of materials used during the procedure by $700.

Treat the Ischemic Lesions and Leave the Rest Alone

Speaking with heartwire , Boden said the results suggest harm in stenting a vessel based only on visual severity. "Depending on the view you are using, you are potentially doing angioplasty on a non–flow-limiting stenosis, one without a gradient, and in that setting you're likely going to buy into more of the risks rather than the benefits of long-term revascularization."

Boden said that he and others are attempting to incorporate FFR testing into an upcoming study called CREEDENCE. "I do think an invasive physiologic assessment of stenosis is critical to optimizing which arteries you should or shouldn't stent."

It is often easier to stent something than to actually think about it.

Also commenting on the FAME results, Dr Ajay Kirtane (Columbia University, New York, NY) told heartwire that the findings emphasize treating the patient and the ischemia and leaving the other vessels alone. "It is often easier to stent something than to actually think about it," said Kirtane. "This study should refocus us on treating lesions that need to be treated, and the other stuff, leave it alone. How we figure out what needs to be treated is by doing some sort of functional test and not relying solely on the angiogram."

Asked about the potential harm of treating vessels that do not need to be treated, Kirtane said treating nonischemic lesions exposes the patient to more risk, but that it is unfair to conclude that conventional PCI causes harm. To be able to definitively state this, the trial would have required a third study arm where hemodynamically significant lesions were left solely to medical therapy.

"Treating lesions that don't need to be treated is not a good thing and can harm people, but treating lesions that need to be treated is also beneficial over leaving them alone," said Kirtane. In the COURAGE nuclear substudy, for example, patients with flow-limiting lesions left to medical therapy fared worse than those treated with PCI, findings that are supported by the DEFER study.

Dr Roxana Mehran (Columbia University, New York, NY), who moderated the press conference, offered some restraint to the enthusiastic conclusions of the FAME investigators, pointing out that the technology is advanced and not every cath lab is equipped with FFR capabilities.

"It's a new technology to be added, and having said that, I don't want to imply it shouldn’t be [used], but to make a strong statement and say you shouldn't be performing angioplasty without FFR is a far stretch for just a single study," said Mehran.

RADI Medical Systems sponsored the FAME study with an unrestricted research grant. Boden was the lead investigator of the COURAGE trial and reports research support from Merck and Abbott Vascular and consulting for CV Therapeutics, Abbott Vascular, and Sanofi-Aventis. Kirtane reports consulting for Medtronic, Abbott Vascular, and Danube Pharmaceuticals and being on the speakers' bureau for the Medicines Company, Abbott Vascular, Medtronic, and St Jude Medical. Mehran reports research support from Boston Scientific. Di Mario reports research support from Trireme, Cordis, Boston Scientific, Abbott Vascular, Terumo Medical Corporation, Medtronic, and Biosensors. He consults for Trireme, Biosensors, and Medtronic.

DEFER: PCI unnecessary for intermediate stenosis with no inducible ischemia. theheart.org. [Clinical Conditions > Interventional/Surgery > Interventional/Surgery]; Sep 26, 2005. Accessed at http://www.theheart.org/article/568297.do on Oct 14, 2008

Experts debate pros and cons of "prophylactic stenting" of vulnerable plaque. theheart.org. [Clinical Conditions > Interventional/Surgery > Interventional/Surgery]; May 26, 2005. Accessed at http://www.theheart.org/article/488775.do on Oct 14, 2008

Coronary flow reserve can be assessed by pressure measurement. theheart.org. [HeartWire > News]; May 9, 2003. Accessed at http://www.theheart.org/article/254057.do on Oct 14, 2008

Fractional flow reserve distinguishes patients who will benefit from angioplasty. theheart.org. [HeartWire > News]; Jun 18, 2001. Accessed at http://www.theheart.org/article/192911.do on Oct 14, 2008

The complete contents of Heartwire , a professional news service of WebMD, can be found at www.theheart.org, a Web site for cardiovascular healthcare professionals.


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