Inclusion Criteria:  requiring coronary angiography to assess coronary artery disease; having at least one angiographically intermediate coronary stenosis (eg. 40%-80%) on any vessel requiring invasive functional assessment using FFR (and/or any other surrogate index) being able and legally entitled to give informed consent  Exclusion Criteria:  history of severe poorly uncontrolled pulmonary disease hemodynamic instability during the diagnostic or therapeutic procedures; known adenosine intolerance need of mechanical circulatory or ventilatory support; stage IV chronic kidney disease. life expectancy <1 year patients gaining indication to surgical revascularization; major procedural complications during percutaneous revascularization (cardiac arrest needing cardiopulmonary resuscitation, major bleeding , large iatrogenic coronary dissection, coronary embolization in a main vessel, suspected stroke) making post-PCI functional evaluation unsafe or impossible.