The following are key points to remember from this state-of-the-art review on invasive coronary physiology after stent implantation:

1. Recurrent angina post–percutaneous coronary intervention (PCI) remains common 1 year after PCI (20-30%).
2. Despite limitations of angiography alone and studies showing a relationship between post-PCI fractional flow reserve (FFR) and cardiovascular events, post-PCI physiological assessment is performed in <10% of lesions undergoing going pre-PCI physiological assessment.
3. Reasons for minimal use of post-PCI FFR include lack of clarity regarding optimal cut-off, need to administer adenosine multiple times, and concerns about how to act on a suboptimal post-PCI FFR.
4. Proposed causes for abnormal FFR values post-PCI include stent-related issues such as stent under-expansion or edge dissection; missed stenoses at the target PCI site; diffuse disease in target vessel; coronary vasospasm; and wire-induced pseudo-stenoses in tortuous segments.
5. Use of non-hyperemic pressure indexes represent an attractive option, which removes the need for adenosine.
6. Resting Pd/Pa measurement post-PCI can be useful if post-PCI Pd/Pa is >0.96. FFR pullback can be performed to interrogate when it is <0.96.
7. Instantaneous wave-free ratio (iFR) pullback offers the advantage of using a non-hyperemic index to map the hemodynamics of an entire vessel on pullback. Abnormal post-PCI iFR can be analyzed to assess for focal pressure drop versus diffuse change.
8. Virtual PCI tools like quantitative flow ratio (QFR) and computed tomography (CT) FFR hold promise for defining patterns of coronary artery disease prior to treatment but in current practice, they require off-line analysis.
9. Pullback pressure gradient (PPG) index is a continuous metric, which may help discriminate between focal or diffuse disease. Values slow to 0 indicating diffuse disease and closer to 1 denoting focal disease. Its application is limited due to need for motorized pullback and prolonged infusion of adenosine.
10. Complete functional PCI requires physiological assessment pre- and post-PCI. Larger-scale trials will be needed to define its precise application.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Stable Ischemic Heart Disease, Vascular Medicine, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease, Interventions and Imaging, Interventions and Vascular Medicine, Angiography, Computed Tomography, Nuclear Imaging, Chronic Angina

Keywords: Adenosine, Angina Pectoris, Angiography, Constriction, Pathologic, Coronary Angiography, Coronary Artery Disease, Coronary Vasospasm, Dissection, Fractional Flow Reserve, Myocardial, Hemodynamics, Hyperemia, Percutaneous Coronary Intervention, Physiology, Stents, Tomography, X-Ray Computed

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