Registry Data Help Shore Up the Case for Functional Assessment in ACS, Multivessel Disease

PARIS, France—Functional assessment is proving feasible and informative when used in the real world to guide treatment decisions in challenging disease subsets, according to late-breaking data presented today at EuroPCR.

Among a string of studies that have come out on the usefulness of fractional flow reserve (FFR) measurement, PRIME-FFR now “is the first one to really give us any meaningful data on acute coronary syndromes,” panelist Justin Davies, MD, PhD (Imperial College London, England), told TCTMD.

The DEFINE REAL study, meanwhile, showed that routinely using instantaneous wave-free ratio (iFR) to assess the impact of flow-restricting lesions in multivessel disease can change the course of treatment for nearly half of patients.


For PRIME-FFR, Luís Raposo, MD (Centro Hospitalar de Lisboa Ocidental, Lisbon, Portugal), and colleagues drew on the R3F and POST-IT registries to include a total study population of 1,983 patients, 29% of whom had ACS. Most of the ACS patients tended to have ongoing symptoms (43%) or unstable angina/NSTEMI (40%); only 17.1% presented with STEMI.

In both the ACS and non-ACS arms, FFR results informed the decisions made in slightly more than 93% of treatment decisions. Similar percentages of ACS and non-ACS patients had their management plans changed based on their FFR results (37.7% vs 39.2%; P = 0.55).

Yet the patterns of reclassification differed (P = 0.024). “The a priori strategy before FFR was quite identical in both groups, with roughly under 60% of patients undergoing medical therapy. But when you look at the final decision after FFR, you can clearly see that the patients being evaluated in the setting of an ACS were significantly more likely to be reclassified into one of the revascularization strategies,” Raposo said in his presentation.

The most important message, he stressed, is that—contrary to popular assumption—the proportion of patients who shifted to revascularization based on FFR did not decrease but actually, in ACS patients, increased from 41.3% before to 51.1% after assessment. In the non-ACS group, the proportion slated for revascularization was 42.6% before and 45.5% after FFR.

“But then again, okay we’ve changed management,” Raposo continued, “but how confident can we be in going against the strategy that was suggested by the angiogram?” Within the ACS group and within the non-ACS group, patients had similar freedom from MACE at 1 year regardless of whether they were reclassified. Among those who had deferred revascularization, ACS patients were no more at risk of MACE than were those in the non-ACS group.

Reassuringly, he said, “hard clinical endpoints were always lower [in ACS patients who had deferred revascularization] than in the patients who were revascularized [while] having an ACS. So that means that when you decide to defer a lesion, you’re not increasing the risk of your patient in any way.” Deferral was equally safe in subgroup analyses separating out patients who had recent versus ongoing ACS and single versus multivessel disease.

One “hypothesis-generating” result, Raposo added, is that the small, 6% slice of patients for whom FFR results were disregarded—be they ACS or non-ACS patients—had nearly double the rate of MACE at 1 year compared with patients whose treatment was guided by FFR. “We cannot claim causality, of course, but it’s surely food for thought [and] something we should keep in mind,” he said.

To TCTMD, Davies pointed out that it is likely no accident that FFR was disregarded in these patients. “There are certain circumstances where FFR is not so reliable in this setting, and that’s when you have a lot of blood clot and the microcirculation is affected,” he noted. Even so, he added, it shows that when it isn’t possible to follow the normal FFR protocol, the outcomes are “pretty dire.”

Moreover, the fact that in terms of 1-year MACE, ACS and non-ACS patients did equally well (10.9% vs 9.5%; P = 0.886) is “quite interesting,” Davies commented.

iFR for Multivessel Disease

Focusing on multivessel disease patients in the DEFINE REAL registry, Eric Van Belle, MD, PhD (Hôpital Cardiologique, Lille, France), said he and fellow researchers employed iFR in an attempt to streamline what is regarded as a time-consuming process when done with conventional FFR. 

They enrolled 484 patients in nine countries, all of whom had at least 40% stenosis in two or more lesions (73% had two-vessel disease and 27% three-vessel disease). Most were type A and B1 lesions. Out of 1,107 vessels, 75% had physiological assessment. While 97% of patients had iFR/FFR and 3% FFR alone, fully 33% had an iFR-driven approach.

Van Belle reported that the added time involved in doing physiological assessment was less than 5 minutes for two vessels and around 8 minutes for three vessels.

Much like in the above registries, physicians were asked to decide on a course of treatment based on angiographic results and clinical information. Once functional assessment was performed, the choice was made again.

Treatment decisions were changed after functional assessment for 30% of vessels and 27% of patients. From a patient’s point of view, the two paths are PCI or no PCI, but for the physician, there could be a change in exactly which of several diseased vessels undergo intervention, Van Belle pointed out. If both sorts of decisions are considered, fully 47% of patients were reclassified in some fashion based on functional assessment.

That so many patients had a fully iFR approach “is a huge story in itself,” Davies said, adding that it “is a measure of confidence in people using newer techniques.” The ease and speed of iFR makes it well suited to multivessel disease, he explained.

“People always give you this illustration of FFR—that you just basically put the wire down and give the adenosine. But in reality, I’d invite you to go to any cath lab around the world and [you’ll see that] invariably the drug’s not available, they’re waiting for the infusion pump, [and the] pump starts beeping and alarming, and they have to change it. This is the nonsense you have to deal with,” Davies commented. But the advantage with iFR, he said, “is that the physician is actually in control. Because once the wire goes down there, and once they normalize, they push it down and press the button and that’s it.” Nor is there any adenosine, he added. 

“There’s been lots of debate, because [iFR] is a new technique and obviously it’s kind of challenged the field a lot,” Davies acknowledged, stressing, though, that the degree to which it was used in this registry is a demonstration of the technology’s maturity.

But until there are large trials showing differences in outcomes, “it’s the same as FFR. Before it had FAME, it was nothing,” he said. 


  • Raposo L. Impact of routine fractional flow reserve on management decision and 1-year clinical outcome of ACS patients: insights from the POST-IT and R3F integrated multicenter registries: implementation of FFR in routine practice (PRIME-FFR). Presented at: EuroPCR 2016. May 19, 2016. Paris, France.
  • Van Belle E. DEFINE REAL: a prospective, observational, non-randomised, European, multicentre registry, collecting real-life information for the utilisation of iFR in assessing coronary stenosis relevance in the multivessel disease patient population. Presented at: EuroPCR 2016. May 19, 2016. Paris, France.


  • Raposo reports serving as a consultant for St. Jude Medical and Volcano Corporation.
  • Van Belle reports receiving honoraria from St. Jude Medical and Volcano Corporation.
  • Davies reports serving as a consultant for Philips Volcano and Medtronic and receiving institutional grant/research support from AstraZeneca, Medtronic, and Philips Volcano.

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