1 IntroductionThe narrowing (commonly called stenosis) of blood vessels alter the regular flow of blood, being one of the most common places where these situations occur in the coronary arteries. When this situation occurs, not enough oxygen reaches the myocardium, leading to ischemic heart disease (stable or unstable angina pectoris, acute myocardial infarction). This disease is caused by sclerosis of the coronary arteries due to the formation of collagen and accumulation of lipids and inflammatory cells.In 1996, (Pijls et al., 1996) determined that there is a direct relationship between blood pressure and flow with maximum vasodilation of the artery (conditions of hyperemia). They defined the Fractional Flow Reserve (FFR), currently used as the gold standard to assess the physiological severity of coronary stenosis, as:FFR = Qms/Qmebeing:Qms: maximum achievable blood flow through a stenosis, conditions of hyperemia.Qme: maximum expected blood flow, without stenosis in the artery.The flow rate is the ratio of the pressure difference to the flow resistance:Qms = (distal diastolic pressure - venous pressure)/maximum resistance vessel stenosis.Qme = (aortic diastolic pressure - venous pressure)/maximum resistance vessel normal.\begin{equation} FFR=\frac{\left(P_{d}-P_{v}\right)/R_{s}}{\left(P_{a}-P_{v}\right)/R_{n}}\nonumber \\ \end{equation}The venous pressure (Pv) is the same and the resistances (Rs, Rn) in hyperemia are minimal, so it has that Fractional Flow Reserve is the ratio between the pressures (average of the cardiac cycle) distal coronary (Pd) and proximal or aortic (Pa) with respect to the stenosis, in conditions of hyperemia:FFR = Pd/PaThis is an invasive test, needing to insert a catheter through the coronary stenosis. The standardized medical protocol (Coppel et al., 2019) suggests measuring the distal coronary pressure (Pd) 2-3 cm downstream of the stenosis. They determined that a cut-off value of 0.75 Fractional Flow Reserve could be correctly determined for patients with ischemia, with 93% accuracy. It is currently considered that, under normal flow conditions, the Fractional Flow Reserve value should be in a range between 0.8 and 1 (Toth et al., 2016). Myocardial ischemia is highly possible when this value is below 0.8. The disadvantage of this process is that it limits the region where the pressure is measured without taking into account the evolution of the pressure field downstream of the stenosis.Since to obtain the distal and aortic pressures it is necessary to perform an invasive test, a possible substitute could be simulating the sanguineous flow in a virtual model using Computational Fluid Dynamics (CFD). This three-dimensional model can obtain from images (Min et al., 2011; Zhang et al., 2018; Owida et al., 2012) of a Coronary Computed Tomography Angiography (CCTA). To obtain clear images of the arteries that supply blood to the heart, an injection of contrast material with iodine is used. This process, known as Fractional Flow Reserve - Computed Tomography (FFRCT), allows visualizing inside the flow all type of variables and, consequently, the distribution of Fractional Flow Reserve in the stenosed artery.The main objective of this study is to deepen this Fractional Flow Reserve - Computed Tomography (FFRCT) technique examining the influence of the location of the measurement point distal coronary pressure (Pd) in the FFRCTvalue. For this purpose, a three-dimensional model was obtained from a Coronary Computed Tomography Angiography of an anonymous patient with coronary stenosis (68%) and simulated using Computational Fluid Dynamics. The results were validated with the data of distal and proximal pressures, acquired simultaneously to the same person.