FFR-SEARCH Explores Potential of Physiologic Assessment After PCI

PARIS, France—Fractional flow reserve (FFR) measurement, when done right after PCI, may be a way to optimize stent placement. Early data from the FFR-SEARCH trial presented in a Hot Line session today at EuroPCR 2017 show that post-stenting, nearly half of patients have FFR values below 0.90 even when stent placement looks fine on angiography.

“Usually we are used to thinking about FFR as a tool to understand if a lesion has to be treated or not,” investigator Roberto Diletti, MD, PhD (Thoraxcenter Erasmus MC, Rotterdam, the Netherlands), said in a press briefing. “Now we can also start thinking about FFR as a tool to understand and evaluate our job after stenting.”

The idea is that FFR could safely and quickly be used to evaluate PCI results. Mean time for FFR assessment in the study was 5 minutes.

Measurements are done at the end of PCI “when the operator was satisfied by the angiographical appearance,” Diletti explained. While maintaining wire access to the vessel, he said, a Navvus microcatheter (ACIST) with an optical pressure sensor is inserted over the previously used coronary guidewire in order to do FFR.

But some experts here at EuroPCR questioned whether the FFR was actually picking up suboptimal stent placement, or if there might be other things at play.

A Chance to Optimize

FFR-SEARCH is a prospective, all-comers registry of 1,512 patients who underwent successful PCI. Among them, 959 had at least one lesion measured by FFR (n = 1,165 lesions). Their clinical presentations were evenly distributed among stable angina, unstable angina/NSTEMI, and acute MI. There were no complications related to FFR measurement.

Almost half of patients (48%) had at least one lesion with an FFR value of 0.90 or less at the end of the procedure. Approximately a quarter (22%) had a value of 0.85 or lower, and 8.9% of lesions had a value of 0.80 or lower, which Diletti pointed out is “below the threshold for ischemia.”

With the cutoff of 0.90, he said, “a relevant percentage of our procedures could be optimized.” It’s possible that such results could help guide procedural optimization, Diletti suggested, but whether such a step could actually lead to better clinical outcomes is not yet known.

MACE included all-cause mortality, MI, and any revascularization. At 30 days, the rates—which spanned from 1.5% for FFR > 0.90 to 2.8% for FFR ≤ 0.80—showed a trend but did not differ significantly by FFR group. However, “this was not the primary aim of the study,” so the lack of difference is unsurprising, he said. “The power calculation for the study was done with an event rate at 2 years.”

That said, Diletti added, “the numbers are going in the right direction, at least in the beginning.”

During his presentation, he said researchers are preparing to conduct FFR-REACT, a randomized trial that will evaluate how IVUS-directed FFR can be used to optimize procedures.

What Next?

Andreas Baumbach, MD (Barts Heart Center, London, England), added a bit of caution against reading too much into the findings. “So basically you showed what’s been shown before with a pressure wire: that at the end of the procedure there is a loose correlation between the FFR. The closer to 1 it is, the better the long-term results,” he commented during the press conference. “But you’ve not shown that the next step can be to optimize the ones that are less than 0.80 and make them closer to 1.”

Diletti said his group is now performing intravascular imaging in an attempt to identify whether procedures can be optimized using FFR, “because sometimes we have really diffuse disease distally and it’s not really doable. But we observe that in a very high rate of cases, . . . you have a focal lesion and poor expansion. That means you can do something about it.”

Asked by TCTMD if operators in the current analysis changed their behavior subsequent to knowing the FFR results, Diletti said this was against protocol and did not occur. “You get the FFR. You don’t do anything, [because] angiographically you think it’s done,” he explained.

In the late-breaking session, panelist Harshawardhan Mardikar, MD (Spandan Heart Institute & Research Institute, Nagpur, India), pointed out that FFR-SEARCH is not the first study to propose this idea. But perhaps, he said, the issue in lesions showing low FFR isn’t subpar stenting but rather a microcirculatory problem.

What sets this study apart, Diletti said, is that it included not only stable but also unstable patients. “This is not a small detail, because when you have unstable patients, you also have thrombotic lesions [and possibly] microvascular impairment.” In STEMI patients, for example, the FFR value “is much higher, it’s not because you are doing probably a better job than usual, it’s because your microvascular function down the road is impaired,” he said, adding that it’s important to consider the clinical presentation of the patient.

Mardikar pointed out that in FFR-SEARCH two-thirds of patients had ACS, making it hard to know what to make of the findings.

So what then, asked session co-moderator David R. Holmes Jr, MD (Mayo Clinic, Rochester, MN), does this mean for clinicians? “You’re in the catheterization laboratory. We do more and more FFR. We put in a stent and we think it looks just great. And then we do an FFR and it doesn’t look all that great. In 2017, next week when that happens in your practice, what are you going to do? Go in with IVUS or OCT and see if the stent looks really good?”

Dilette said that this is the “natural next step.” Treating any missed lesions or using postdilatation to further expand the stent are both options. Around 14% of patients have diffuse disease, he said, and in those cases he would not do additional stenting.

Yet Mardikar did not seem convinced, saying: “It is a doubt in my mind that possibly what we are picking up is residual microcirculatory dysfunction.” Rather than pursuing additional imaging, it might make more sense to try to identify patients with this issue, he suggested, perhaps “treating them better in the postangioplasty phase with vasodilators, ongoing nitroglycerin, [etc].”