Comparison of Instantaneous Wave-Free Ratio (iFR) and Fractional Flow Reserve (FFR) with respect to Their Sensitivities to Cardiovascular Factors: A Computational Model-Based Study

Figure 6

Effects of different combinations of AS (with its severity being controlled by the value of EOA_sys) and increased coronary microvascular resistance (R_cmv, herein normalized by its reference normal value) on (a) iFR and (b) FFR. Increasing the severity of AS leads to a marked decrease in iFR and moderate increase in FFR, whereas increasing R_cmv causes a progressive increase in both iFR and FFR. As a consequence, increasing R_cmv counteracts or even reverses the decrease in iFR while augments the increase in FFR caused by AS. Note that the coronary stenosis is present in mid-LAD with its severity being fixed at 50% in all the simulations and that the values of iFR and FFR highlighted by the filled circles indicate their reference values computed under the condition that only the 50% coronary stenosis is present while AS and increased R_cmv are absent.

(a)

(b)