What is the role of fractional flow reserve (FFR) monitoring during percutaneous coronary intervention (PCI)?

Updated: Nov 27, 2019
  • Author: George A Stouffer, III, MD; Chief Editor: Karlheinz Peter, MD, PhD  more...
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Intracoronary Doppler pressure wires are used to characterize coronary lesion physiology and estimate lesion hemodynamic severity. Comparison of the pressure distal to a lesion with aortic pressure at maximal coronary hyperemia enables determination of fractional flow reserve (FFR) (see the image below).

Fractional flow ratio (FFR). Pressure wire is adva Fractional flow ratio (FFR). Pressure wire is advanced across left anterior descending (LAD) artery stenosis, and intracoronary adenosine is given. FFR ratio is recorded at baseline and then after adenosine push is given. Here, LAD lesion and FFR post adenosine are shown.

An FFR measurement lower than 0.80 during maximal hyperemia (induced via administration of adenosine) is consistent with a hemodynamically significant lesion. This determination is useful in deciding whether to perform PCI in an angiographic intermediate lesion. Clinical data—namely, the findings from the DEFER (Deferral of Percutaneous Coronary Intervention) study—support using this approach; a low event rate was seen in medically managed patients with angina and an FFR measurement greater than 0.75.

The FAME (Fractional Flow Reserve versus Angiography for Guiding PCI in Patients with Multivessel Coronary Artery Disease) trial showed that routine measurement of FFR during angioplasty reduced the risk of death, MI, or repeat revascularization by 30% and the risk of death or MI by 35%, compared with the current practice of using angiography to guide stenting decisions. [87]

In this study, a cutoff FFR value of 0.80 was used to define a nonischemic lesion. A 2-year follow-up of the FAME trial showed continuing significant reductions in the combined endpoint of death and MI with the use of FFR in comparison with standard angiography-guided PCI. [88]

The FAME 2 trial randomly assigned patients with stable CAD who had at least one stenosis with an FFR less than 0.8 to receive either FFR-guided PCI plus optimal medical therapy or optimal medical therapy alone. [89] The occurrence of the primary endpoint—a composite of any-cause mortality, nonfatal MI, or urgent revascularization within 2 years—was significantly lower in the PCI group than in the medical therapy group (8.1% vs 19.5%).

However, it is important to note that this difference in primary endpoint was primarily driven by a reduction in the rate of urgent revascularization in the PCI group (4% vs 16.3); there were no significant between-group differences in mortality and MI rate. [89]

The FAME 3 study, currently under way, is a multinational multicenter trial designed to compare FFR-guided PCI (using second-generation DESs) with coronary artery bypass grafting (CABG) in patients with multivessel CAD.

Currently, the use of FFR is recommended to assess the hemodynamic significance of angiographically intermediate (40-70%) stenosis. Both FFR and IVUS have shown favorable outcomes when used to assess angiographically intermediate lesions; however, the data on FFR are more robust.

A meta-analysis by Johnson et al indicated that FFR values should be viewed not only in the context of a cut point used in deciding whether to revascularize patients through PCI but also as part of a spectrum of values indicating which patients will receive the most benefit from PCI. [90]

The analysis, which utilized data from FFR trials (9173 lesions) and patient-level data (6961 lesions), supported the use of the 0.75-0.80 range, the same range employed in major FFR studies, as the optimal cut point for PCI; however, the results also indicated that the further beneath that range a patient’s FFR falls, the more benefit the patient will receive from PCI. [90] Johnson et al also found evidence that measuring the FFR after PCI can aid in determining a patient’s prognosis, with higher post-PCI numbers being associated with lower subsequent event rates.

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