Spatial Relationship Between Coronary Microvascular Dysfunction and Delayed Contrast Enhancement in Patients with Hypertrophic

To clarify the spatial relationship between coronary microvascu-lar dysfunction andmyocardial fibrosis in hypertrophic cardiomy-opathy (HCM), we compared the measurement of hyperemic myocardial blood flow (hMBF) by PET with the extent of delayed contrast enhancement (DCE) detected by MRI. Methods: In 34 patients with HCM, PET was performed using 13N-labeled am-monia during hyperemia induced by intravenous dipyridamole. DCE and systolic thickening were assessed by MRI. Left ventric-ular myocardial segments were classified as with DCE, either transmural (DCE-T) or nontransmural (DCE-NT), and without DCE, either contiguous to DCE segments (NoDCE-C) or remote from them (NoDCE-R). Results: In the group with DCE, hMBF was significantly lower than in the group without DCE (1.81 6 0.94 vs. 2.13 6 1.11 mL/min/g; P, 0.001). DCE-T segments had lower hMBF than did DCE-NT segments (1.43 6 0.52 vs