Atherosclerotic involvement of the coronary arteries of adolescents and young adults.

Coronary atherosclerotic plaques were revealed by light microscopy in 12% of adolescents and in 28% of young adults. All the plaques of adolescents and one-third of the plaques of young adults escaped recognition on ordinary gross inspection, even after Sudan staining. A centrifugal extention of plaques, from the branching areas to the proximal segment of the main coronary arteries took place, starting from adolscence. During early adulthood this centrifugal extension continued involving the intermediate segments of the anterior descending and right coronary arteries. In undistended vessels, the coronary atherosclerotic plaques narrowed the lumenal diameter up to 55% in adolescents and up to 65% in young adults. Histologically, the mucoid type of plaque, rich in areas of edema, insudate and depolymerized ground substance, prevailed in the coronary arteries of adolescents; in young adults, the prevalent plaque was the lipid-rich variety, containing many clusters of lipid-filled and foam cells. In addition, necrotic plaques or atheromas have been revealed for the first time in young adults. A positive association appeared on our material between cigarette smoking and the presence of mucoid plaques in the proximal segment of the main coronary arteries of adolescents. On the other hand, no relation could be established between risk factors and the accumulation of lipid-filled and foam cells in the atherosclerotic plaques of young adults.