Abstract 17791: Association of Enhanced Adventitial Vasa Vasorum Formation With Atherosclerotic Changes in the Human Coronary Arteries Adjacent to Myocardial Bridging -An Optical Frequency Domain Imaging Study

Abstract

Background: Although myocardial bridge (MB) has been implicated as a cause of adverse cardiac events, its pathological significance remains to be fully elucidated. Recent advance in imaging with optical frequency domain imaging (OFDI) has enabled us to precisely evaluate the coronary arterial wall in humans, including adventitial vasa vasorum (VV). In the present study, we thus examined with OFDI whether coronary adventitial VV formation is enhanced in the MB segments in humans and if so, whether there is any correlation between adventitial VV formation and atherosclerotic changes. Methods and Results: We examined 15 consecutive patients (age 67±2, M/F 7/8) who were diagnosed as having MB in the left anterior descending coronary arteries without significant organic stenosis in the present OFDI study. MB was diagnosed by CAG when systolic compression was noted, as previously reported. The cross-sectional OFDI showed diffuse enhancement of VV formation at the proximal and distal segments compared with the MB site ( Figure A ). Quantitative analysis at every 1-2 mm length showed that adventitial VV area density on OFDI was significantly greater at both the proximal and the distal segments compared with the MB site (0.122±0.005 vs. 0.075±0.003 vs. 0.108±0.005 mm 2 /mm 2 , P<0.001) ( Figure B ). In addition, intimal (I) + medial (M) area was significantly greater at the proximal segments compared with the MB site and the distal segments. (2.70±0.12 vs. 1.66±0.07 vs. 1.83±0.11 mm 2 , P<0.001) ( Figure C ). Importantly, there was a significant positive correlation between the extent of VV formation and that of I+M area in the coronary artery (R=0.582, P<0.0001) ( Figure D ). Conclusions: These results suggest an important role of adventitial VV formation in the pathogenesis of human coronary atherosclerosis adjacent to the MB, for which altered blood turbulence may be involved.