Off Target: Optimal Post-PCI FFR Often Missed

Patrice Wendling

October 23, 2020

Optimization of fractional flow reserve (FFR) after angiographically successful percutaneous coronary intervention (PCI) did not impact clinical outcomes but significantly reduced the proportion of patients leaving the cath lab with an FFR of 0.80 or less in a single-center randomized trial.

After standard-of-care PCI, only 32% of patients achieved a post-PCI FFR of at least 0.90, which has been shown to be associated with a lower risk for repeat PCI and major adverse cardiovascular events.

Perhaps more concerning, 29% of patients had a final FFR at or below the guideline-recommended revascularization threshold of 0.80, said study author Damien Collison, MD, Golden Jubilee National Hospital and University of Glasgow, United Kingdom.

The TARGET-FFR trial involved 260 patients with coronary artery disease, including stable angina and non-ST-segment myocardial infarction, who were randomly assigned after angiographically successful PCI to blinded post-PCI coronary physiology assessment or to a physiology-guided incremental optimization strategy (PIOS).

If a patient in the PIOS group had a suboptimal FFR less than 0.90, the physiology results were disclosed to the operator and further optimization advised based on the results of FFR pullback assessment.

Specifically, if the FFR pullback indicated diffuse disease pattern with no focal step-ups and the hyperemic trans-stent gradient (HTG) was less than 0.05 units, the case was deemed complete, Collison said.

If the HTG was at least 0.05, postdilatation with a larger noncompliant balloon to 18 atm was advised, and if a focal step-up of at least 0.05 was identified outside the stented segment, an additional stent was recommended. Finally, FFR pullback was repeated and if either of the two previous criteria were present, operators could perform further postdilatation or deploy one additional stent.

Based on FFR pullback assessment, a substrate for further optimization was present in 60 of 131 (46%) PIOS patients. Operators felt it appropriate to perform additional post-dilatation and/or stenting in 66% of these patients.

Among these 40 cases, both FFR and coronary flow reserve (CFR) increased from means of 0.76 to 0.82 (P <.001) and from 3.0 to 4.0 (= .02), respectively, Collison reported in a late-breaking session at the virtual Transcatheter Cardiovascular Therapeutics (TCT) 2020.

The proportion of patients with a final FFR of at least 0.90 — the study's primary end point — increased from 28.1% to 38.1% with PIOS, but this did not achieve statistical significance based on a hypothesized 20% between-group difference (P = .09).

The PIOS strategy, however, did significantly reduce the proportion of patients with a final FFR of 0.80 or less (18.6% vs 29.8%; P = .045).

Not unexpectedly, this came at the cost of significantly longer procedure (94 vs 67 minutes) and fluoroscopy (23 vs 16 minutes) times, as well as higher radiation (921 vs 686 mGy) and adenosine (93 vs 62 mg) doses, Collison said.

Procedural complications were similar in each group (2.5 vs 9.5 without PIOS; P =.14).

At a median of 105 days, there was no difference in the change in the Seattle Angina Questionaire-7 summary score or its individual domains between the two groups.

One target vessel failure and one cardiac death occurred in the PIOS group, compared with no such events among control subjects over a median of 1.7 years.

In an analysis stratified by target vessel, there was no significant difference in pre-PCI FFR or CFR. But mean post-PCI FFR was considerably lower in the left anterior descending (LAD) artery than in the left circumflex or right coronary arteries (0.80 vs 0.92 vs 0.91; P <.001), which supports previous registry data that an LAD target lesion is a consistent predictor of suboptimal post-PCI FFR results, Collison said.

Discussant Bernard De Bruyne, MD, PhD, OLV Clinic, Aalst, Belgium, said the study lacked power to prove PIOS could improve patient outcomes or achieve higher FFR values but highlights the need for different FFR cutoffs in different vessels.

"The LAD is really a different animal in terms of post-PCI FFR and, actually even pre-PCI FFR," and can have an FFR already in the region of 0.8 without stenosis to start with, "which is never the case in the right coronary artery," he said. "So probably in the future we will have to conceive studies targeting different thresholds, especially the right and the LAD."

Collison observed that, perhaps confusingly, registry data has already proposed that the LAD should have either a higher or lower optimal threshold than other vessels. "Between you and I and the world, if you want to achieve FFRs of 0.90, you should change your practice to just stent right coronaries and left circumflex," he quipped.

Discussant Allen Jeremias, MD, St. Francis Hospital, Roslyn, New York, said TARGET-FFR is an eye-opening study.

"I'm a little bit shocked that residual ischemia is even greater than we saw in DEFINE-PCI and really only a third of these have an optimal outcome with an FFR of more than 0.90 with angiographic guidance alone," he said. "So I think it really reinforces the importance of doing physiology before and after to guide PCI to get to better outcomes."

The results also underline the importance of FFR pullback assessment, which is underutilized, Jeremias suggested. "We leave a lot of information on the table."

In a TCT wrap-up video, Roxana Mehran, MD, Icahn School of Medicine at Mount Sinai, New York City, said she also was shocked that so few patients met the 0.90 criteria but expressed some hesitancy about the FFR thresholds post-PCI.

"We just presented Xience data with such a low event rate and, believe me, they're not doing FFR at the end of every one of those procedures," she said. "So if that's the case, then we should have had a lot more events. So I don't think that an FFR of 0.80 actually holds true for clinical events postprocedure as it does preprocedure of whether you should go ahead to do something or not. And I think you can do harm if you just keep going."

The study was sponsored by the NHS National Waiting Times Centre Board. Collison reported consulting fees/honoraria from Abbott Medical and MedAlliance.

Transcatheter Cardiovascular Therapeutics (TCT) 2020. Presented October 16, 2020.

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