Distribution of tissue characteristics of coronary plaques evaluated by integrated backscatter intravascular ultrasound: Differences between the inner and outer vessel curvature

Background: The purpose of the present study was to evaluate the tissue characteristics of plaques with moderate or mild stenosis in the inner and outer curvature of the left anterior descending artery (LAD) using integrated backscatter intravascular ultrasound. Methods: We evaluated 66 plaques with moderate stenosis (plaque burden >50% but <= 75%) and 49 plaques with mild stenosis (plaque burden >30% but <= 50%) in 66 patients undergoing percutaneous intervention to the LAD. All plaques were >10 mm away from any side branch or previously implanted stents. We divided vessel cross-sections into four quadrants (inner curvature, outer curvature, clockwise lateral side, and counterclockwise lateral side) using the septal branch as a landmark for the inner curvature. We averaged relative lipid area, relative fibrous area, and relative calcified area in minimal lumen area (MLA), three cross-sections proximal to the site of MLA, and three cross-sections distal to the site of MLA. Results: In plaques with moderate stenosis, the relative lipid area in the inner curvature was significantly greater than in the outer curvature and lateral sides, whereas there was no significant difference in plaques with mild stenosis. Conclusion: The present study provides new findings that lipid pool is clustered in the inner curvature and fibrous tissue is clustered in the outer curvature of plaques with moderate stenosis in non-branching LAD lesions. (C) 2015 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.