Aim: To review the current approaches to simplify functional assessment of coronary stenosis with particular regard for contrast Fractional Flow Reserve (cFFR). Methods and results: Maximal hyperaemia to assess FFR is perceived as time-consuming, costly, unpleasant for the patient and associated with side effects. Resting indexes, like Pd/Pa and iFR, have been proposed to circumvent the use of vasodilators as well as an approach based on the administration of contrast medium to induce coronary vasodilation, the cFFR. Contrast FFR can be obtained quickly, at very low cost in the absence of substantial side effects. Among these alternative indexes, cFFR shows the best correlation with FFR, reduces the use of adenosine even more than a hybrid ...