Current status and future perspectives of fractional flow reserve derived from invasive coronary angiography

Abstract

Assessment of the functional significance of coronary artery stenosis using invasive measurement of fractional flow reserve (FFR) or non-hyperemic indices has been shown to be safe and effective in making clinical decisions on whether to perform percutaneous coronary intervention (PCI). Despite strong evidence from clinical trials, utilization of these techniques is still relatively low worldwide. This may be to some extent attributed to factors that are inherent to invasive measurements like prolongation of the procedure, side effects of drugs that induce hyperemia, additional steps that the operator should perform, the possibility to damage the vessel with the wire, and additional costs. During the last few years, there was a growing interest in the non-invasive assessment of coronary artery lesions, which may provide interventionalist with important physiological information regarding lesion severity and overcome some of the limitations. Several dedicated software solutions are available on the market that could provide an estimation of FFR using 3D reconstruction of the interrogated vessel derived from two separated angiographic projections taken during diagnostic coronary angiography. Furthermore, some of them use data about aortic pressure and frame count to more accurately calculate pressure drop (and FFR). The ideal non-invasive system should be integrated into the workflow of the cath lab and performed online (during the diagnostic procedure), thereby not prolonging procedural time significantly, and giving the operator additional information like vessel size, lesion length, and possible post-PCI FFR value. Following the development of these technologies, they were all evaluated in clinical trials where good correlation and agreement with invasive FFR (considered the gold standard) were demonstrated. Currently, only one trial (FAVOR III China) with clinical outcomes was completed and demonstrated that QFR-guided PCI may provide better results at 1-year follow-up as compared to the angiography-guided approach. We are awaiting the results of a few other trials with clinical outcomes that test the performance of these indices in guiding PCI against either FFR or angiography-based approach, in various clinical settings. Herein we will present an overview of the currently available data, a critical review of the major clinical trials, and further directions of development for the five most widely available non-invasive indices: QFR, vFFR, FFRangio, caFFR, and AccuFFRangio.

Performance of the Angiography Derived FFR (vFFR) in the Evaluation of Coronary Stenoses in Comparison with FFR

“…However, it is a prospective trial involving six centers and 334 patients (diagnosed with stable angina or NSTE-ACS), aimed for the same purpose and showed same results. Similarly to our study, it confirmed a good correlation of vFFR with FFR but r was equal to 0.74, p < 0.001 [11].…”

Virtual Hemodynamic Assessment of Coronary Lesions: The Advent of Functional Angiography and Coronary Imaging

“…Patients whose QFR assessment altered the intended revascularization strategy benefited the most (HR: 0.66; 95% CI: 0.54-0.81; p < 0.0001), driven by fewer MIs (4.0% vs. 6.8%; HR: 0.58; 95% CI: 0.44-0.77; p¼ 0.0002) and ischemia-driven revascularizations (4.2% vs. 5.8%; HR: 0.71; 95% CI: 0.53-0.95; p¼ 0.02). In the randomized PANDA III trial [48], the QFR was retrospectively analyzed from the angiograms of 1391 patients who were grouped into those having had QFR-consistent treatment (all functionally ischemic vessels [baseline QFR ≤ 0.80] were treated and all non-ischemic vessels [baseline QFR > 0.80] were deferred) and those having had QFR-inconsistent treatment. QFR-consistent PCI was performed on 814 (58.5%) patients overall, whereas QFR-inconsistent PCI was performed on 577 (41.5%) patients.…”

Pressure Never Lies, but It Should Be Interpreted Thoughtfully: The Role of Hydrostatic Pressure in Coronary Physiology

“…Angiography-derived (or image-based) techniques can determine FFR through computational fluid dynamic (CFD) calculations or simplified fluid dynamic equations using 3D reconstruction from invasive angiography. Among the many software packages, including Cardiovascular Angiographic Analysis Systems for vessel Fractional Flow Reserve (CAAS vFFR; Pie Medical Imaging, Maastricht, The Netherlands), FFRangio (CathWorks, Newport Beach, CA, USA), caFFR (Rainmed, Suzhou, China), and Accu FFRangio (ArteryFlow Technology, Hangzhou, China), the most widely used software is Quantitative Flow Ratio (QFR) by Medis Medical Imaging (Leiden, The Netherlands), which has conducted the most clinical validation studies in CAD patients, including both chronic and acute coronary syndrome cases [ 9 ].…”