Background Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) is associated with fewer unfavorable events.However,the hemodynamic change in FFR after different stenting approaches for bifurcation lesions is still not fully studied.The aim of this study was to analyze the hemodynamic changes in FFR after double kissing (DK)crush and provisional side branch (SB) stenting (PS) for true coronary bifurcation lesions.Methods Seventy-five patients with true bifurcated lesions were randomly divided into DK (n=38) and PS (n=37)groups.Additional SB stenting in the PS group was required if there was any pinched SB ostium ＞70％ stenosis.or ≥ type B dissection,or TIMI flow ＜grade 3.FFR at hyperemia in the main vessel (MV) and SB was measured prior- and post-stenting,and at 8 months follow-up.Results Baseline clinical,angiographic and lesion characteristics were matched well between the two groups,with the exception of the final kissing balloon inflation (FKBI,100.0％ in the DK vs.83.8％ in the PS group,P ＜0.001).Baseline FFR was comparable between the DK and the PS groups,however,the acute gain and late loss of SB FFR at 8-month follow-up in the DK group were 0.18±0.15 and -0.06±0.11,compared to 0.12±0.18 (P=0.044) and -0.002±0.07 (P=0.037)in the PS group,respectively.MV FFR post-stenting ＞0.94 was seen in about 40％ of patients.There was no significant difference in the clinical events at 1-year follow-up between the two groups.Conclusions DK crush was associated with improved acute gain and late loss of SB FFR.The lower rate of FFR ＞0.94 after stenting underscored the further improvement of stenting quality.