Methods and Results: FFR pull-back and intravascular ultrasound (IVUS) were performed after successful PCI in 135 left anterior descending artery lesions. ?FFRstent was defined as the FFR gradient across the stent. The ?FFRstent/length was defined as the ?FFRstent value divided by the total stent length multiplied by 10 [= (?FFRstent ÷ stent length) x 10]. Major adverse cardiac events (MACEs) were the composite of all-cause death, target vessel related myocardial infarction, and target lesion revascularisation. Despite successful PCI without significant complications on IVUS, ?FFRstent > 0 was observed in 98.5% of cases. ?FFRstent =0.04 and ?FFRstent/length = 0.009 predicted suboptimal stenting defined as final minimal stent area < 5.5 mm². During 2183 ± 898 days, the MACE-free survival rate was significantly lower in patients with ?FFRstent = 0.04 and ?FFRstent/length = 0.009 compared to those with lower values (69.6 vs. 93.4%, log-rank p = 0.031; 72.1 vs. 97.7%, log-rank p =0.003, respectively). ?FFRstent/length = 0.009 (hazard ratio 10.1, p = 0.032) was an independent predictor of MACE.
Conclusion: A trans-stent FFR gradient was frequently observed in DES-treated patients despite successful PCI results. ?FFRstent and ?FFRstent/length are useful indicators for optimising a DES and are related to long-term outcomes.