Importance of measuring the fractional flow reserve in patients receiving hemodialysis

Angiography is not always an accurate indicator of physiologically significant stenosis. We examined the usefulness of functional evaluation of coronary stenosis severity by determining the fractional flow reserve (FFR) using a pressure wire in patients who received hemodialysis with angiographically intermediate lesions. We recruited 44 patients with intermediate lesions; of these, 22 were undergoing hemodialysis while 22 were not. Quantitative coronary angiography (QCA) was performed to measure the minimal lumen diameter (MLD) and calculate the percent diameter stenosis (%DS). The FFR was calculated as the ratio of the coronary pressure at the distal stenotic site to the mean aortic pressure during maximum hyperemia. In each group, we investigated the relationship between the FFR and %DS and FFR and MLD. The patients in the hemodialysis group were significantly younger and had more calcified and type B2/C lesions than those in the non-dialysis group. Although the FFR was correlated with both %DS (r = 0.71, p < 0.01) and MLD (r = 0.58, p < 0.01) in the non-dialysis group, the FFR was not correlated with either MLD or %DS in the hemodialysis group. In the hemodialysis group, there was a discordance between the QCA- and FFR-based assessments of the severity of coronary stenosis. In patients receiving hemodialysis, both anatomical and functional assessments should be conducted to determine the physiological significance of the stenosis accurately.