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Sex Differences in iFR- or FFR-Guided Revascularization Strategy
Study Questions:
Are there sex-based differences in procedural characteristics and clinical outcomes of instantaneous wave-free ratio (iFR)– and fractional flow reserve (FFR)–guided revascularization strategies?
Methods:
This was a post hoc analysis from the DEFINE-FLAIR (Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularization) study, which compared iFR-based strategy to FFR. This analysis sought to assess sex-based differences between iFR and FFR strategies and compare 1-year major adverse cardiac event rates (composite of death, nonfatal myocardial infarction, or unplanned revascularization).
Results:
A total of 601 women and 1,891 men were randomized to iFR- or FFR-guided strategy. Among the entire population, women had a lower number of functionally significant lesions per patient (0.31 ± 0.51 vs. 0.43 ± 0.59; p < 0.001) and less frequently underwent revascularization than men (42.1% vs. 53.1%; p < 0.001). There was no difference in mean iFR value according to sex (0.91 ± 0.09 vs. 0.91 ± 0.10; p = 0.442). However, the mean FFR value was lower in men than in women (0.83 ± 0.09 vs. 0.85 ± 0.10; p = 0.001). In men, an FFR-guided strategy was associated with a higher rate of revascularization than an iFR-guided strategy (57.1% vs. 49.3%; p = 0.001), but this difference was not observed in women (41.4% vs. 42.6%; p = 0.757). There was no difference in MACE rates between iFR- and FFR-guided strategies in both women (5.4% vs. 5.6%, adjusted hazard ratio, 1.10; 95% confidence interval, 0.50-2.43; p = 0.805) and men (6.6% vs. 7.0%, adjusted hazard ratio, 0.98; 95% confidence interval, 0.66-1.46; p = 0.919).
Conclusions:
An FFR-guided strategy was associated with a higher rate of revascularization than iFR-guided strategy in men, but not in women. However, iFR- and FFR-guided strategies showed comparable clinical outcomes, regardless of sex.
Perspective:
This is a post hoc analysis attempting to better delineate sex-based differences in iFR- and FFR-based revascularization strategies. Keeping the limitation of a retrospective analysis and the fact that the number of total women enrolled was low (280 in iFR group and 321 in FFR group) in mind, women appear to have lower rates of revascularization compared to men regardless of which physiologic index was used. There were differences in mean FFR with women having higher FFR, but no sex-based difference in iFR. There was no difference in clinical outcomes between men and women or strategy used (iFR or FFR). The findings of this study add to the growing body of literature suggesting that there are sex-based differences in the pathophysiology of ischemic heart disease driven by the role of the coronary microvascular circulation. Larger studies (all female cohort) will be needed to understand and define the relationship between microvascular dysfunction and coronary physiology indices currently used to guide revascularization.
Keywords: Cardiology Interventions, Constriction, Pathologic, Coronary Artery Disease, Coronary Circulation, Fractional Flow Reserve, Myocardial, Myocardial Infarction, Myocardial Ischemia, Myocardial Revascularization, Sex Characteristics, Treatment Outcome
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