Criteria of Myocardial Fractional Flow Reserve and Coronary Flow Ratio for Detection of Myocardial Ischemia in Patients with Kawasaki Disease

Abstract

Purpose of this study is to estimate the criteria of myocardial fractional flow reserve (FFRmyo) and coronary flow ratio (CFR) for detection of silent myocardial ischemia. 112 patients (1y-15y) were divided into three groups; normal coronary or coronary dilation without stenosis (N) group (n=61), coronary stenosis without ischemia (n-IS) group (n=30), myocardial ischemia (IS) group (n=21) by 2-D echo, and rest and exercised myocardial scintigraphy. FFRmyo is defined as the ratio of maximal achievable flow in myocardium subtended by a stenosed coronary artery to the maximal achievable myocardial flow induced by papaverine. CFR was calculated as a ratio of averaged peak velocity before and after papaverine. FFRmyo and CFR were calculated and compared among three groups. Sensitivity and specificity for detection of myocardial ischemia were calculated by abnormal values of FFRmyo and CFR. Moreover, FFRmyo and CFR tests estimated effectiveness of PTCA and CABG. Results: Criteria for detection of myocardial ischemia were defined the mean±2sds for values of FFRmyo and CFR in N group; <0.75 in FFRmyo and <2.0 in CFR. FFRmyo and CFR in IS group (0.64±0.3#, 1.2±0.4#) were significantly decrease (# p<0.05). Sensitivity and specificity for detection of myocardial ischemia were very high by FFRmyo and CFR. Moreover, FFRmyo and CFR were very useful index for analysis of coronary blood flow velocity and pressure dynamics before and after PTCA and CABG. Conclusions: The values of <0.75 in FFRmyo and <2.0 in CFR can be useful to estimate myocardial ischemia and to evaluate the effectiveness of PTCA and CABG.