Natural history of abnormal fractional flow reserve (FFR) ≤0.8 but intact coronary flow reserve (CFR) ≥2 is not noninferior to lesions with FFR >0.8/CFR ≥2, based on findings from the DEFINE-FLOW study presented Oct. 16 during TCT 2020.

Researchers, including Nils Johnson, MD, FACC, assessed data from 430 patients, of whom the median age was 67 and 74% were male. Patients were placed in four groups: 1) medical therapy and FFR >0.8/CFR ≥2 (N=207); medical therapy and FFR >0.8/CFR <2.0 (N=108); medical therapy and FFR ≤0.8/CFR ≥2 .0 (N=74); and revascularized by PCI and FFR ≤0.8/CFR <2.0 (N=94). The primary endpoint was a composite of all-cause death, myocardial infarction (MI) and PCI/CABG after two years.

The overall results proved the hypothesis that FFR ≤0.8/CFR) ≥2 is not noninferior to lesions with FFR >0.8/CFR ≥2. However, Johnson, et al., highlighted several limitations that need to be addressed in future research in order to move beyond hypothesis-generating discussions. Among the limitations: lack of randomization, modest sample size, slow enrollment, unblinded subjects and clinicians, and few “hard endpoints,” as well as few lesions with severe FFR/CFR.

In addition to the DEFINE-FLOW results, findings from the DEFINE-PCI study were also presented as part of TCT 2020 late-breaking science. The DEFINE-PCI study found that patients who were highly symptomatic at baseline without residual ischemia by post-PCI instant wave-Free Ratio (iFR) (iFR ≥0.95) tended to have greater improvements in anginal symptoms at one year compared with patients with residual ischemia.

Manesh Patel, MD, FACC, et al., also observed that a post-PCI iFR ≥0.95 was associated with less cardiac death, spontaneous MI, or clinically-driven target vessel revascularization compared with a post-PCI iFR<0.95 (1.8% vs. 5.7% respectively, p=0.04).

DEFINE-PCI investigators noted that the clinical effectiveness of iFR guidance (target iFR ≥0.95) to identify and eliminate post-PCI ischemia will be studied in the DEFINE-GPS trial.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention

Keywords: TCT20, Transcatheter Cardiovascular Therapeutics, Percutaneous Coronary Intervention, Fractional Flow Reserve, Myocardial, Coronary Stenosis

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