Agreement between coronary flow velocity reserve and stress echocardiography in intermediate‐severity coronary stenoses

Visual and quantitative assessments of percent diameter stenosis on coronary angiography correlate poorly with functional testing, particularly in intermediate-severity (40%-70%) lesions, yet are frequently relied on to make decisions regarding revascularization. Coronary flow velocity reserve (CFVR) and relative CFVR (RCFVR) are promising methods for on-line functional assessment of lesion severity in the catheterization laboratory. We sought to determine the agreement between maximal, mean, and relative CFVR and stress echocardiography in intermediate-severity stenoses. The results of exercise or dobutamine stress echocardiography and CFVR measured by intracoronary Doppler were compared in 28 patients referred for assessment of intermediate-severity stenoses, using 15 patients with either angiographically normal coronary arteries or diameter stenoses > 70% as reference groups. CFVR was measured at least three times in response to a bolus of adenosine in the target vessel distal to the stenosis. RCFVR (target/normal vessel CFVR) was also measured in 27 patients. Maximal, mean (of three measures), and relative CFVR were calculated. CFVR > or = 2.0 and RCFVR > or = 0.75 were accepted as normal. A minority (29%) of patients in the intermediate-severity stenosis group had a positive test by either method. There was good to very good agreement between stress echocardiography and maximal CFVR (84%, kappa = 0.62, P < 0.0001) and RCFVR (81%, kappa = 0.59, P < 0.001) across the entire patient cohort, though in the intermediate subgroup concordance was only fair. Using the mean (of three measures of) CFVR for the same comparison improved the agreement in the intermediate subgroup to good (86%, kappa = 0.58, P = 0.002), and in the entire cohort the agreement was very good (88%, kappa = 0.74, P < 0.0001). There was only fair correlation between measures of CFVR and percent coronary stenosis. CFVR improved from 1.8 +/- 0.8 to 2.7 +/- 0.7 after percutaneous intervention (n = 12, P < 0.0001). These results suggest that there is good agreement between CFVR and stress echocardiography across a wide range of coronary lesion severity. The mean of three CFVR measurements distal to the target vessel stenosis increases diagnostic accuracy. Intracoronary Doppler flow velocity measurements at the time of cardiac catheterization may facilitate improved decision-making by providing the ability to assess the functional significance of coronary stenoses on-line.