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Coronary angiography has limited efficacy in identifying patients with suboptimal results after percutaneous coronary intervention (PCI). Immediate post-procedural functional assessment, including fractional flow reserve (FFR), is emerging as an effective tool for this purpose whereas with limited clinical adoption. Image-based computational FFR has been recently developed as an alternative without the need for costly pressure wire or hyperaemia-inducing medications. This thesis investigated the utility of image-based computational FFR assessment in predicting and evaluating the physiological efficacy of PCI. In the first part of the thesis, the relationship between post-PCI wire-based FFR and clinical outcomes was investigated using a systematic review and study-level meta analysis, pooling 12340 patients and 12923 vessels from 62 studies. Mean post-PCI FFR was not continuously associated with 1-year major adverse cardiac events (MACE) including all-cause death, myocardial infarction (MI), and target vessel revascularization (TVR). Still, risk ratio favoured high post-PCI FFR for reduced MACE, all-cause death, MI, TVR and better angina status under different cut-offs. The second part of the thesis focused on the utility of image-based FFR in post-PCI settings. The feasibility and accuracy of an optical coherence tomography (OCT)- based optical flow ratio (OFR) in predicting post-PCI FFR was evaluated. Post-PCI OFR was computed in 125 pullbacks from 119 patients with both OCT and FFR interrogation immediately after PCI. After eliminating the stenotic segment by virtual stenting, simulated residual OFR from pre-PCI OCT images was computed in 64 patients who had pre-PCI OCT. The accuracy in predicting post-PCI FFR ≤0.90 was 84% for post-PCI OFR and 80% for simulated residual OFR. Stent minimum expansion index was associated with in-stent pressure drop (r = -0.49, p