Relative Fractional Flow Reserve Increase and Final Fractional Flow Reserve After Percutaneous Coronary Intervention

Post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) and relative FFR increase after PCI are determined by the interaction of baseline disease pattern, adequacy of PCI, and residual disease burden in a target vessel. However, the prognostic impact of relative FFR increase after PCI remains uncertain.

The aim of this study was to evaluate the prognostic relevance of relative FFR increase in addition to post-PCI FFR in patients undergoing PCI.

From the International Post PCI FFR Extended Registry, 1,497 patients with pre-PCI FFR ≤0.80 were analyzed. The relative FFR increase was expressed as a percentage and calculated as percentage FFR increase (ΔFFR%) with PCI ([post-PCI FFR - pre-PCI FFR]/pre-PCI FFR × 100). The primary endpoint was 5-year target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction, or target vessel revascularization (TVR). TVR was further specified as target lesion revascularization (TLR) or non-TLR TVR.

Maximally selected log-rank statistics identified 15.0% and 0.80 as the cutoffs to discriminate the occurrence of TVF for ΔFFR% and post-PCI FFR, respectively. Failure to meet either cutoff was associated with increased risk for TVF (ΔFFR%: 10.9% [122 of 1,148] vs 17.6% [59 of 349] [adjusted HR: 1.72; 95% CI: 1.23-2.42; P = 0.002]; post-PCI FFR: 10.9% [136 of 1,279] vs 21.3% [45 of 218] [adjusted HR: 2.08; 95% CI: 1.47-2.94; P < 0.001]). Patients with post-PCI FFR ≤0.80 had increased TVF compared with those with post-PCI FFR >0.80, regardless of sufficient (≥15.0%) or insufficient (<15.0%) relative FFR increase. The higher risk for TVF in patients with post-PCI FFR ≤ 0.80 compared with those with post-PCI FFR >0.80 was driven primarily by non-TLR TVR (2.2% vs 6.0%; P = 0.015) in the sufficient ΔFFR% group (≥15.0%), whereas it was attributable mainly to TLR (6.6% vs 17.0%; P = 0.008) in the insufficient ΔFFR% group (<15.0%).

Relative FFR increase after PCI provides prognostic implications comparable with post-PCI FFR. Among patients with insufficient relative FFR increase, post-PCI FFR ≤0.80 was associated with an increased risk for restenosis within stented segments, whereas among those with sufficient relative FFR increase, post-PCI FFR ≤0.80 was associated with risk driven by disease progression in nonstented segments.