Fractional Flow Reserve: Does a Cut-off Value add Value?

Abstract

CoronaryFractional flow reserve (FFR) is an index used to describe the physiological significance of a coronary stenosis. It measures the pressure drop under conditions of maximal hyperaemia between the aorta and a selected vessel location distal to an angiographic lesion. 1 Several FFR studies have identified patient groups in whom coronary stenting is associated with improved outcomes when compared with medical therapy (and vice versa). FFR-guided treatment prevents unnecessary stenting and therefore coronary physiology has been associated with improved outcomes at reduced cost, a rare combination in a new technology.2-7 Coronary physiological assessment is now an integral part of the modern catheterisation laboratory, with a level 1A recommendation by the European Society of Cardiology (ESC) for use in stable patients in whom evidence of ischaemia is not already available. Ischaemic Heart Disease and Coronary RevascularisationAngina is the clinical manifestation of myocardial ischaemia in patients with stable coronary artery disease (CAD). It is caused by transient imbalance between blood supply and metabolic demand. The myocardial ischemia that causes angina is, however, not simply a question of a 'blocked pipe'; rather, ischaemia is a result of complex pathophysiological mechanisms that include obstructive epicardial CAD, inflammation, microvascular coronary dysfunction, endothelial dysfunction, thrombosis and angiogenesis (see Figure 1). 10Obstructive epicardial CAD is only one of the factors that contributes to myocardial ischaemia and yet, in the treatment of ischaemic heart disease (IHD), great (some would say overwhelming) emphasis is given to identifying and eliminating obstructive epicardial CAD over other potential causes of ischaemia, some of which may have key therapeutic roles in treating patients with IHD. The reason for this emphasis is obvious -obstructive epicardial CAD is easily identified, easily understood and relatively easily treated by angiography and stenting or bypass grafting. Doing so, however, does not always relieve ischaemia. Concept and Validation of Fractional Flow ReserveWhen FFR is used to identify a potentially ischaemia-causing lesion, the aim is to identify deficient blood flow distal to a coronary lesion.However, unlike coronary pressure, measurement of coronary blood flow in the catheter laboratory is not technically straightforward. positive non-invasive test may still occur, but sensitivity and specificity were sub-optimal. Clinical judgement was therefore advised for values in this range. The FAME studies then moved the FFR cut-off point to ≤0.80, with a view to predicting outcomes. The ≤0.80 cut-off point has been adopted into clinical practice guidelines, whereas the lower value of ≤0.75 is no longer widely used. Here, the authors discuss the data underpinning these cut-off values and the practical implications for their use when using FFR guidance in PCI. KeywordsCoronary physiology, fractional flow reserve, pressure wire Disclosure: SRM and TRK have received rese...

Diagnostic and Prognostic Value of Stress Cardiovascular Magnetic Resonance Imaging in Patients With Known or Suspected Coronary Artery Disease

“…Notably, FFR was first calibrated against noninvasive tests, including bicycle exercise testing, thallium scintigraphy, and stress echocardiography with dobutamine, which were themselves validated against ICA as the reference test, resulting in problematic circular thinking . An FFR threshold of 0.80 or lower has been adopted into clinical practice guidelines as an actionable value to guide revascularization despite robust evidence supporting larger treatment benefit at lower FFR values; our findings indicate better agreement at an FFR threshold of 0.75.…”

Fractional flow reserve and non-hyperemic indices: Essential tools for percutaneous coronary interventions

“…Maximal hyperemia is generally obtained by intravenous or intracoronary perfusion of adenosine[ 17 ]. Other agents such as Regadenoson or Papaverine can also be used[ 18 , 19 ].…”

Is it the Time to Move Towards Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve Guided Percutaneous Coronary Intervention? The Pros and Cons

“…Therefore, the lesion’s severity significantly affects the diagnostic accuracy of FFR, as clinical justification is difficult and controversial within the “grey zone” of FFR, between 0.75 and 0.85, in cases with intermediate lesions [ 48 ]. Therefore, it is suggested to reconsider the FFR cut-off used for the treatment decision based on the complexity of the coronary lesion [ 49 ].…”