BACKGROUND: Fractional flow reserve (FFR) specifically relates to the severity of a stenosis to the mass of tissue to be perfused. Accordingly, the larger the territory to be perfused, the greater the flow and the pressure gradient induced by maximal hyperemia. Although this notion may be considered intuitive, its unequivocal demonstration is still lacking. The aim of our study was to evaluate the influence of the amount of myocardium subtended to an intermediate stenosis on FFR, especially in relation to quantitative coronary angiography. METHODS AND RESULTS: The severity of each lesion was assessed by FFR and 2-dimensional quantitative coronary angiography. The amount of jeopardized myocardium was evaluated using 3 validated scores specifically adapted to this aim: the Duke Jeopardy Score (DJS), the Myocardial Jeopardy Index (MJI), and the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) Lesion Score (ALS). The presence of a concomitant collateralized chronic total occlusion was also reported. A total of 213 intermediate coronary stenoses in 184 patients were enrolled. FFR values were correlated to minimal lumen diameter (r=0.34; P