Fractional Flow Reserve Directed Percutaneous Coronary Intervention Optimization Using High-Definition Intravascular Ultrasound in Non-ST-Segment Elevation Acute Coronary Syndrome Versus Chronic Coronary Syndrome

Background: Intravascular ultrasound (IVUS)-guided optimization of suboptimal fractional flow reserve (FFR) following percutaneous coronary intervention (PCI) results in a significant increase in both post-PCI FFR and minimal lumen and stent areas (MLA and MSA, respectively). However, the impact of clinical presentation with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) versus chronic coronary syndrome (CCS) on the efficacy of PCI optimization remains unknown.

Methods: This was a prespecified subgroup analysis of the FFR REACT trial comparing IVUS-guided PCI optimization versus no further treatment in 291 patients with a post-PCI FFR < 0.90. Post-PCI physiology and pre optimization IVUS findings were compared between patients presenting with NSTE-ACS versus CCS, as well as optimization strategy, final FFR and IVUS findings.

Results: Out of 291 patients, 130 (44.7%) presented with NSTE-ACS. Median post-PCI FFR was similar in patients with NSTE-ACS and CCS (0.85 for both, p = 0.55). Pre optimization IVUS findings did not differ significantly between both groups and subsequent optimization strategy was comparable (p = 0.71). In both NSTE-ACS and CCS, optimization resulted in a significant increase (p < 0.01 for all) of similar magnitude in median FFR (0.02 vs. 0.03, p = 0.80), MLA (0.37 vs. 0.50 mm², p = 0.46) and MSA (0.29 vs. 0.32 mm², p = 0.61), respectively. The clinical impact of IVUS-guided optimization on 2-year target vessel failure showed no signs of heterogeneity based on clinical presentation (interaction p = 0.36).

Conclusions: In patients undergoing FFR-directed IVUS-guided optimization, post-PCI FFR, pre optimization IVUS findings and optimization strategy did not differ significantly between patients presenting with either NSTE-ACS or CCS, with comparable improvements in FFR, MLA and MSA.