Impact of Sex on the Functional Assessment of Intermediate Coronary Lesions by Instantaneous Wave-Free Ratio

Sex differences in coronary physiology and in the pathogenesis of coronary artery disease (CAD) have been previously described. Contrasting data have been reported, so far, about the impact of sex on the assessment of the functional significance of intermediate coronary stenoses by fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR). The present study aimed at assessing the sex differences in the results of iFR in a cohort of patients undergoing coronary angiography.

Methods: We included patients undergoing coronary angiography and the functional assessment of intermediate (40 to 70%) coronary lesions in 2 centers. iFR measurement was performed by pressure-recording guidewire and automatically calculated at the core laboratory using the manufacturers' dedicated software. Quantitative parameters of the coronary lesions were calculated by an automatic edge-detection system. Minimal luminal diameter (MLD), reference diameter (RD), percent diameter stenosis, and length of the lesion were measured. Positive iFR was considered for values < 0.90.

Results: We included 325 patients undergoing coronary angiography and iFR evaluation of 371 intermediate coronary stenoses, including 20.6% of women. Females were older, displayed lower body weight and hemoglobin, lower rate of active smoking (p < 0.001) and previous PCI (p = 0.04), lower platelet count (p = 0.001) and creatinine (p = 0.02). Systolic blood pressure and heart rate at admission were more elevated in women (p = 0.001 and p = 0.05, respectively). At angiography, multivessel coronary artery disease was more uncommon (p = 0.001) and proximal lesions were more frequently assessed by iFR (p = 0.04). Mean values of iFR did not differ with sex and neither the percentage of positive iFR (19.1% vs 18.8%, p = 0.99, adjusted OR[95%CI] = 0.51[0.18-1.48], p = 0.22).

Conclusion: Among patients undergoing functional assessment of intermediate coronary lesions by instantaneous wave-free ratio, no impact of sex was observed on the absolute values or the rate of positivity of iFR.