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Introduction Computed tomography derived fractional-flow reserve studies (CTFFR) can supplement CT-coronary angiography (CTCA) in determining functional significance of stenosis. 1 However, evidence comparing invasive coronary angiogram (ICA) outcomes between CTCA alone versus CTFFR guided approaches that accounts for baseline risk differences is limited.Methods Single-centre retrospective CTCA audit data for chronic coronary syndrome patients from 2020-2023 was analysed. Baseline risk was calculated using the recommended risk-factor weighted clinical likelihood (RF-CL) model.1 ICA recommendation after CTCA was defined as cases where ICA was performed urgently or following initial medical management. True positives were patients who underwent interventional revascularization after ICA. Positive-predictive value (PPV) after ICA was compared between CTCA versus CTFFR. Subgroup analysis was conducted in patients reported as moderate and severe stenosis on CTCA.Results ICA was recommended in 189 patients after CTCA, where 62 (32.8%) had CTFFR. Overall, ICA was positive in 111 (58.7%) patients where PPV was 57.5% for CTCA alone and 61.3% for CTFFR. PPV peaked when RF-CL risk was >=31%, where CTFFR showed PPV 77.5 (95% CI: 62.5-87.7) versus 63.8 (95% CI: 52.8-73.4) in CTCA alone (figure 1). ICA recommendation was more frequent in severe (63.4%) compared to moderate stenosis (26.5%). The effect of RF-CL risk was retained among subgroups where CTFFR consistently improved ICA PPV when baseline risk was >=31% (figures 2 and 3).Conclusion CTFFR improved ICA yield only at higher RF-CL risks, supporting a risk-stratified approach to CTFFR referral. Due to low event rates, larger multicentre studies are required to confirm these findings.Reference Vrints C, Andreotti F, Koskinas KC, et al. 2024 ESC Guidelines for the management of chronic coronary syndromes. Eur Heart J. 2024;45(36):3415–537. doi:10.1093/eurheartj/ehae177 In patients with chronic coronary syndrome undergoing CTCA, what did this study conclude about the role of CTFFR in improving invasive coronary angiography (ICA) outcomes?A. CTFFR improved ICA positive-predictive value (PPV) across all baseline risk groups regardless of clinical likelihood.B. CTFFR improved ICA PPV primarily in patients with higher baseline risk (RF-CL 16-30%).C. CTFFR improved ICA PPV primarily in patients with higher baseline risk (RF-CL ≥31%).D. CTCA alone had a higher PPV than CTFFR all baseline risk groups regardless of clinical likelihood.Abstract 25 Figure 2Abstract 25 Figure 3Abstract 25 Figure 1E. CTCA alone improved ICA PPV primarily in patients with higher baseline risk (RF-CL 16-30%).