Sex Differences in Instantaneous Wave-Free Ratio or Fractional Flow Reserve–Guided Revascularization Strategy.

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Abstract

Objectives: This study sought to evaluate sex differences in procedural characteristics and clinical outcomes of instantaneous wave-free ratio (iFR)- and fractional flow reserve (FFR)-guided revascularization strategies. Background: While iFR-guided strategy has shown a lower revascularization rate than FFR-guided strategy without the difference in clinical outcomes between the 2 strategies, the influence of male versus female sex has not yet been fully investigated. Methods: This is a post-hoc analysis of DEFINE-FLAIR (Functional Lesion Assessment of Intermediate stenosis to guide Revascularization) study, in which 601 women and 1,891 men were randomized to iFR- or FFR-guided strategy. iFR≤0.89 and FFR≤0.80 were used as criteria for revascularization. The primary endpoint was 1-year major adverse cardiac events (MACE), a composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization. Results: Among the entire population, women had 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 sex difference in iFR value (0.91 ± 0.09 vs. 0.91 ± 0. 10, p = 0.442). However, FFR value was lower in men than in women (0.83 ± 0.09 vs. 0.85 ± 0.10, p = 0.001). In men, FFR-guided strategy was associated with a higher rate of revascularization than iFR-guided strategy (57.1% vs. 49.3%, p = 0.001). There was no difference in revascularization rate between iFR- and FFR-guided strategies in women (41.4% vs. 42.6%, p = 0.757). At 1 year, MACE rate was not different according to sex (women vs. men, 5.49% vs. 6.77%, adjusted HR 0.82, 95% CI 0.53-1.28, p = 0.380). There was no difference in MACE rates between iFR- and FFR-guided strategies in both women (5.36% vs. 5.61%, adjusted HR 1.10, 95% CI 0.50-2.43, p = 0.805) and men (6.55% vs. 7.00%, adjusted HR 0.98, 95% CI 0.66-1.46, p = 0.919). Conclusions: 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 treatment strategies showed comparable clinical outcome, regardless of sex.