Determinants of insufficient improvement in fractional flow reserve following percutaneous coronary intervention

Fractional flow reserve (FFR) has become an increasingly important index for decision making concerning coronary revascularization. It is commonly accepted that significant improvement in FFR following percutaneous coronary intervention (PCI) is associated with better symptomatic relief and a lower event rate. However, in lesions with insufficient FFR improvement, PCI may not improve prognosis. Leading to the observation that the clinical and angiographic characteristics associated with insufficient FFR improvement have not been fully explored. The purpose of this study was to investigate the factors associated with insufficient improvement in FFR. Using our own PCI database, established between January 2014 and December 2018, we identified 220 stable coronary artery lesions, which had been evaluated for both pre- and post-PCI FFR values. All 220 of these lesions were included in this study. The improvement in FFR (ΔFFR) was calculated in each lesion with the lowest quartile of ΔFFR being defined as the lowest ΔFFR group, and the other quartiles being defined as the intermediate-high ΔFFR group. The mean ΔFFR in the lowest and intermediate-high ΔFFR groups was 0.07 ± 0.02 and 0.21 ± 0.11, respectively. In multivariate logistic regression analysis, a short total stent length (10 mm increase: OR 0.67, 95% CI 0.47-0.96, P = 0.030), higher pre-PCI FFR (0.1 increase: OR 4.07, 95% CI 1.83-9.06, P = 0.001), in-stent restenosis (ISR) (OR 8.02, 95% CI 1.26-51.09, P = 0.028), myocardial infarction (MI) in the target vessel (OR 6.87, 95% CI 1.19-39.69, P = 0.031) and non-use of intravascular imaging (OR 0.35, 95% CI 0.12-0.99, P = 0.048) were significantly associated with the lowest ΔFFR group. The use of short stents, higher pre-PCI FFR values, ISR, MI in the target vessel, and non-use of intravascular imaging were significantly associated with insufficient FFR improvement. It was conversely suggested that full coverage and adequate dilatation of the lesions under an intravascular imaging guidance might contribute to an improvement in FFR.