Sex Differences in Coronary Computed Tomography Angiography–Derived Fractional Flow Reserve

This study is to determine the management and clinical outcomes of patients investigated with coronary computed tomography angiography (CCTA)–derived fractional flow reserve (FFRCT) according to sex. Women are underdiagnosed with conventional ischemia testing, have lower rates of obstructive coronary artery disease (CAD) at invasive coronary angiography (ICA), yet higher mortality compared to men. Whether FFRCT improves sex-based patient management decisions compared to CCTA alone is unknown. Subjects with symptoms and CAD on CCTA were enrolled (2015 to 2017). Demographics, symptom status, CCTA anatomy, coronary volume to myocardial mass ratio (V/M), lowest FFRCT values, and management plans were captured. Endpoints included reclassification rate between CCTA and FFRCT management plans, incidence of ICA demonstrating obstructive CAD (≥50% stenosis) and revascularization rates. A total of 4,737 patients (n = 1,603 females, 33.8%) underwent CCTA and FFRCT. Women were older (age 68 ± 10 years vs. 65 ± 10 years; p < 0.0001) with more atypical symptoms (41.5% vs. 33.9%; p < 0.0001). Women had less obstructive CAD (65.4% vs. 74.7%; p < 0.0001) at CCTA, higher FFRCT (0.76 ± 0.10 vs. 0.73 ± 0.10; p < 0.0001), and lower likelihood of positive FFRCT ≤ 0.80 for the same degree stenosis (p < 0.0001). A positive FFRCT ≤0.80 resulted in equal referral to ICA (n = 510 [54.5%] vs. n = 1,249 [56.5%]; p = 0.31), but more nonobstructive CAD (n = 208 [32.1%] vs. n = 354 [24.5%]; p = 0.0003) and less revascularization (n = 294 [31.4%] vs. n = 800 [36.2%]; p < 0.0001) in women, unless the FFRCT was ≤0.75 where revascularization rates were similar (n = 253 [41.9%] vs. n = 715 [46.4%]; p = 0.06). Women have a higher V/M ratio (26.17 ± 7.58 mm3/g vs. 24.76 ± 7.22 mm3/g; p < 0.0001) that is associated with higher FFRCT independent of degree stenosis (p < 0.001). Predictors of revascularization included stenosis severity, FFRCT, symptoms, and V/M ratio (p < 0.001) but not female sex (p = 0.284). FFRCT differs between the sexes, as women have a higher FFRCT for the same degree of stenosis. In FFRCT-positive CAD, women have less obstructive CAD at ICA and less revascularization, which is associated with higher V/M ratio. The findings suggest that CAD and FFRCT variations by sex need specific interpretation as these differences may affect therapeutic decision making and clinical outcomes. (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Care [ADVANCE]; NCT02499679)