Abstract 20355: Cardiac Magnetic Resonance Assessment of Absolute Myocardial Blood Flow and Myocardial Perfusion Reserve Compared With FFR in Patients With Coronary Artery Disease

Background: The diagnostic value of absolute myocardial blood flow (AMBF) obtained by cardiac magnetic resonance (CMR) quantitative measurement remains uncertain. We evaluated the subendocardial, epicardial, transmural AMBF, and myocardial perfusion reserve (MPR) derived from AMBF determined by perfusion CMR. We also assessed the relationship between CMR-derived AMBF and fractional flow reserve (FFR) in patients with coronary artery disease (CAD). Methods and Results: We investigated 38 CAD patients (mean age, 67±10 years; male, 89%, 46 vessels territories) who underwent perfusion CMR both at stress and rest, and invasive coronary angiography. FFR was measured in all vessels with stenosis more than 40% by QCA. FFR<0.8 was considered hemodynamically significant stenosis. Patients with previous revascularization and/or myocardial infarction, and with renal dysfunction were excluded. We perform quantitative analysis of the transmural, subendocardial and epicardial AMBF, and MPR at mid-ventricular level. AMBF distributed in the wide range both subendocardium and subepicardium. At stress, AMBF was significantly increased in all of the subendocardial, epicardial, and transmural layers of the ischemic segment at adenosine-induced hyperemia from rest AMBF. (At rest: subendocardial 245±122 ml/100g/min, epicardial 124 [75-233] ml/100g/min, transmural 172 [102-261] ml/100mg/min. At stress: subendocardial 380 [156-517] ml/100g/min, epicardial 275 [158-502] ml/100g/mintransmural 287 [152-456] ml/100g/min.) There was a significant relationship between transmural AMBF and FFR, transmural MPR and FFR values, with r = 0.33 (p = 0.028), r=0.39 (p=0.007). The transmural MPR<2.47 threshold yielded a sensitivity of 0.92 (95% confidence interval: 0.77 to 0.99) and a specificity of 0.71 (0.44-0.90) to detect coronary ischemia with a FFR <0.8, and an area under the ROC curve (AUC) of 0.77 (0.62 to 0.88) for vessel-based analysis. Subendocardial AMBF and MPR gradually decreased with decreasing FFR at ischemic segment, but it was not significant. Conclusions: The quantitative analysis of transmural AMBF and myocardial MPR on perfusion cardiac magnetic resonance may predicts hemodynamically significant CAD as defined by FFR.