Incidence, topography and light-microscopic feature of coronary atherosclerotic plaques in adults 26--35 years old.

Coronary atherosclerotic plaques have been found in 42% of adults 26--30 years old and in 58% of adults 31--35 years old. The incidence in these two age-groups of one, two and three vessel involvement is presented, as well as the age-related topography and prevalent histologic type of coronary atherosclerotic plaques. In 26--35 year-old adults, the coronary atherosclerotic plaques appeared non-complicated by thrombosis and/or hemorrhage and narrowed the lumen of undistended vessels up to 75%. The period of life from 26 to 35 years included the critical time for a massive necrosis of certain areas of the thickened intimas, as well as of preexisting and newly formed plaques; consequently, atheroma became prevalent over other atherosclerotic lesions. Necrosis did not result from a break up of lipid-filled and foam cells, its main pathogenetic mechanism being a complex hydrolysis involving progressively the components of the ground substance, fibers and cells.