FFR & IVUS: Putting Tools to Good Use

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Fig-3a-IVUS.jpg - FFR
A stent has been placed in the mid left anterior descending artery across the origin of the diagonal. Despite the angiographic appearance of an ostial diagonal narrowing, FFR in the diagonal shows that it is not flow-limiting and no further intervention is needed.
Source: John McB. Hodgson, MD

Think of fractional flow reserve (FFR) as a hex wrench. Or intravascular ultrasound (IVUS) as a screwdriver. Both imaging methods are highly useful in the right situation, according to physicians. Both methods can be highly effective, when used. However, there is some disagreement about where and when these tools should be applied.

Recently, a web survey offered physicians a perfect world setting to assess stenosis. Physicians could choose to look at provided angiographic surveys of intermediate stenoses or request further data from FFR, IVUS, quantitative coronary angiography or optical coherence tomography. Requests did not add time or costs; all physicians needed to do was to click a button. Nearly three-quarters of decisions made, however, were based solely on angiogram. Combined, physicians requested quantitative coronary angiography, IVUS and optical coherence tomography in only 7 percent of cases (Circ Cardiovasc Interv 2014;7[6]:751-759).

The international report examined adherence to both European and American guidelines for assessing stenosis. The report noted that while physicians with more experience with a modality were more likely to use something other than angiography to assess lesions, rates were still low.

A sign post (of where we are)

“One of the major motivations at the time was to get a cross-sectional view of where people were at considering what has been several years of strong clinical trial results and fairly strong clinical guideline recommendations for the use of FFR for intermediate lesions,” says Nils Johnson, MD, of the Memorial Hermann Hospital in Houston. Johnson has led several studies on FFR and its value in understanding stenosis. While not part of the International Study on Interventional Strategy (ISIS) team, Johnson has paid close attention to these findings to explain what might be driving what he sees as underutilization in the U.S.

Going back to 2009, FAME (Fractional flow reserve versus Angiography for Multivessel Evaluation) and other studies established the utility of FFR for determining lesion severity and which, if any, stenoses needed stenting (Circulation 2014; 129: 1860-1870). In turn, these studies influenced the development of guidelines. “Obviously it’s no surprise whenever you try to change something, it’s not an instantaneous effect in the world,” Johnson says. “There’s always some time lag between when we decide we should be doing something differently and then when clinicians take that on as the majority. [ISIS] was a sense of where we are now.”

Analyses in the U.S. found that IVUS was more frequently used than FFR, although rates were still low. In 2010, FFR and IVUS use was around 6.1 percent and 20.3 percent, respectively (J Am Coll Cardiol 2012;60[22]:2337-2339). These numbers hadn’t improved much in the subsequent two years in Medicare patients. FFR alone was used with 11 percent and 3.9 percent of PCIs and diagnostic catheterizations, respectively (J Am Coll Cardiol 2014;64[16]:1655-1657).

The findings from ISIS and other studies underscore the conundrum: Why aren’t physicians making use of these tools? Johnson states that the answer is more complex than just one of guidelines or clinical trials, or even that of time, staffing or cost of procedure. “An important piece of ISIS’s [message] is that having this almost platonic survey where you say, ‘Don’t think about cost, don’t worry about what you have in your lab, let’s be in a test-taking environment’ … You can still see that even with all of those barriers removed there’s a real dominance of using angiography to decide treatment strategies for intermediate stenosis, even though evidence and the guidelines and everything else says that we should be using FFR in those cases.”

He also notes that physician characteristics, like experience and years of practice, weren’t enough to capture what is driving use—or lack of use—among physicians.

But why not?

Apparently, reasons physicians cite for not using IVUS or FFR haven’t changed much. “We did a survey in the mid ’90s,” says John McB. Hodgson, MD, professor of medicine at Case Western Reserve School of Medicine in Cleveland. “[Physicians said] it was cost. It was time. It was ‘I don’t understand what I’m looking at.’” Hodgson notes that in spite of efforts to improve education and a significant body of data behind the benefits of using IVUS, adoption has been slow.

“The culture in [the U.S.] is ‘We’re not going to do it.’ The culture in Japan is ‘Of course, we’ll