While　coronary　revascularization　strategies　guided　by　instantaneous　wave-free　ratio　(iFR)　are,　in　general,　noninferior　to　those　guided　by　fractional　flow　reserve　(FFR)　with　respect　to　the　rate　of　major　adverse　cardiac　events　at　one-year　follow-up　in　patients　with　stable　angina　or　an　acute　coronary　syndrome,　the　overall　accuracy　of　diagnosis　with　iFR　in　large　patient　cohorts　is　about　80%　compared　with　the　diagnosis　with　FFR.　So　far,　it　remains　incompletely　understood　what　factors　contribute　to　the　discordant　diagnosis　between　iFR　and　FFR.　In　this　study,　a　computational　method　was　used　to　systemically　investigate　the　respective　effects　of　various　cardiovascular　factors　on　FFR　and　iFR.　The　results　showed　that　deterioration　in　aortic　valve　disease　(e.g.,　regurgitation　or　stenosis)　led　to　a　marked　decrease　in　iFR　and　a　mild　increase　in　FFR　given　fixed　severity　of　coronary　artery　stenosis　and　that　increasing　coronary　microvascular　resistance　caused　a　considerable　increase　in　both　iFR　and　FFR,　but　the　degree　of　increase　in　iFR　was　lower　than　that　in　FFR.　These　findings　suggest　that　there　is　a　high　probability　of　discordant　diagnosis　between　iFR　and　FFR　in　patients　with　severe　aortic　valve　disease　or　coronary　microcirculation　dysfunction.