Determining the significance of intermediate coronary stenoses remains a limitation of quantitative coronary angiography. Both intracoronary imaging and physiology have become integral in both the assessment and management decisions of such lesions. Although physiologic testing using fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) is well-established, the interpretation of the sex differences is less understood and remains controversial. This is particularly important for lesions that fall within the gray zone of FFR (0.75–0.8). In the FAME substudy evaluating sex difference [1] , higher values of FFR measurements were found in women even for similar degrees of coronary artery stenosis: 21.1% vs. 39.5%; P < 0.001; nevertheless, the same 0.8 threshold was associated with a similar relative risk reduction in major adverse cardiovascular events (MACE) with the use of FFR. Notably, Kim et al. reported higher MACE when deferral of revascularization was recommended for those within this zone. They noted that women had higher rates of death and myocardial infarction (MI) while men had higher revascularization rates [1] . As for iFR, a post hoc analysis of DEFINE-FLAIR (Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularisation) compared 1-year MACE rates in men and women. The analysis noted that women had a higher mean FFR value compared with men, but fewer revascularizations, whether assessment was performed with FFR or iFR [2] . The authors reported no sex difference in mean iFR values (0.91 ± 0.09 vs. 0.91 ± 0.10; P = 0.442).