Computational instantaneous wave‐free ratio (IFR) for patient‐specific coronary artery stenoses using 1D network models

Abstract

In this work, we estimate the diagnostic threshold of the instantaneous wave‐free ratio (iFR) through the use of a one‐dimensional haemodynamic framework. To this end, we first compared the computed fractional flow reserve (cFFR) predicted from a 1D computational framework with invasive clinical measurements. The framework shows excellent promise and utilises minimal patient data from a cohort of 52 patients with a total of 66 stenoses. The diagnostic accuracy of the cFFR model was 75.76 %, with a sensitivity of 71.43 %, a specificity of 77.78 %, a positive predictive value of 60 %, and a negative predictive value of 85.37 %. The validated model was then used to estimate the diagnostic threshold of iFR. The model determined a quadratic relationship between cFFR and the ciFR. The iFR diagnostic threshold was determined to be 0.8910 from a receiver operating characteristic curve that is in the range of 0.89 to 0.9 that is normally reported in clinical studies.

Abstract

In this work we estimate the diagnostic threshold of iFR through the use of a one‐dimentional haemodynamic model. The 1D model is first validated through a comparison with invasive fractional flow reserve measurements, for which a diagnostic accuracy of 75.76% was achieved. The one‐dimentional model was then utilised to compare cFFR and ciFR on patient‐specific arterial geometries that were extracted via CCTA. The diagnostic threshold of iFR was determined to be 0.891 which is in the normal range reported from invasive clinical studies.