Computerised Methodologies for Non-Invasive Angiography-Derived Fractional Flow Reserve Assessment: A Critical Review

Abstract

Fractional flow reserve is the gold standard for assessing the haemodynamic significance of intermediate coronary artery stenoses. Cumulative evidence has shown that FFR-guided revascularisation reduces stent implantations and improves patient outcomes. However, despite the wealth of evidence and guideline recommendations, its use in clinical practice remains minimal. Patient and technical limitations of FFR as well as the need for intracoronary instrumentation, use of adenosine, and increased costs have limited FFR’s applicability in clinical practice. Over the last decade, several angiography-derived FFR software packages have been developed which do not require intracoronary pressure assessment with a guidewire or need for administration of hyperaemic agents. At present, there are 3 commercially available software packages and several other non-commercial technologies that have been described in the literature. These technologies have been validated against invasive FFR showing good accuracy and correlation. However, the methodology behind these solutions is different—some algorithms are based on solving the governing equations of fluid dynamics such as the Navier–Stokes equation while others have opted for a more simplified mathematical formula approach. The aim of this review is to critically appraise the methodology behind all the known angiography-derived FFR technologies highlighting the key differences and limitations.

Prognostic Value of Coronary Angiography-Derived Fractional Flow Reserve Immediately After Stenting

“…Compared to the traditional pressure wire-based FFR, Coronary angiography-derived FFR does not need wire placement and is adenosine-free, the total operation times are also greatly shortened ( 20 – 23 ). Using invasive FFR as standard, a number of studies have confirmed the diagnostic accuracy of at least four kinds of angiography-derived FFR ( 23 , 24 ), including one novel computational pressure-flow dynamics (CPFD) derived FFR (caFFR) developed by our team ( 23 ). Both caFFR and quantitative flow ratio (QFR) are angiography-based FFR computational products.…”

Comparing QFR and FFR in small vessels—Expanding the spectrum of use

“…QFR, like all other angio‐derived FFR methods, 5 will need further study in a large cross‐section of angiographic subtypes and clinical scenarios, and, of course, coupled to outcome studies before becoming a standard of care. This study provides reassurance that QFR works for all vessel sizes and is another step toward validating angiographic FFR for everyday use.…”

CT-based fractional flow reserve: development and expanded application

“…Whilst this approach has been shown to be effective in reliably predicting FFR, it requires the use of an invasive procedure. Information on this approach has been reviewed elsewhere [12]. raw CT images [13], right: the centreline of an arterial tree reconstructed using a machine-learning enhancement [5].…”

“…Whilst this approach has been shown to be effective in reliably predicting FFR, it requires the use of an invasive procedure. Information on this approach has been reviewed elsewhere 12 .…”