Variations with age in the topographic distribution of coronary atherosclerotic lesions as assessed by image analysis

The localization of macroscopic coronary atherosclerotic lesions was investigated for 184 cases by image analysis. Atherosclerotic lesions were classified into 2 types: fatty streaks and raised lesions. The overall distribution of fatty streaks in arteries involved only by fatty streaks and the distribution of raised lesions in those arteries having raised lesions were demonstrated at similar sites in 3 coronary vessels. If the localization of lesions was examined within age groups, those sites involved with fatty streaks in one age group were replaced with raised lesions in the next older age group; fatty streaks in this older group were located distally to the raised lesions. Subsequently the areas occupied with fatty streaks were replaced with raised lesions in the next older age group. Furthermore, raised lesions seldom appeared at the site where fatty streaks had not existed in the preceding age group. Similar changes in topographic distribution were present if such changes were analyzed according to extent of atherosclerosis. Data from cases with myocardial bridges show that both fatty streaks and raised lesions are seldom observed in the region distal to myocardial bridge. We conclude, thus, that fatty streaks are the precursors of raised lesions in the coronary artery.