Fractional flow reserve (FFR) is an invasive pressure-derived index of epicardial stenosis severity used in the catheterization laboratory to assess the hemodynamic significance of coronary lesions when non-invasive functional assessment has either not been performed or is inconclusive. The use of invasive coronary physiology has demonstrated favorable outcomes for decision making in patients with intermediate single-vessel disease, with left main stenosis, complex bifurcations lesions and multivessel coronary artery disease. Specifically, in patients with stable angina revascularization with either percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery should be deferred for epicardial coronary stenosis with an FFR > 0.8.