Age and fibroplasia as preconditions for atheronecrosis in human coronary arteries.

The first 8 cm of the left circumflex, anterior descending, and right coronary arteries in 173 autopsies of men and women aged 15 to 69 years were examined in hematoxylineosin-stained, paraffin-embedded sections. With increasing age, the intima thickened with fibroproliferative tissue, approaching a threshold of about 150 micron, beyond which atheronecrosis became likely. Compared with the lateral thoracic aorta, the coronaries revealed (1) lower threshold for atheronecrosis, (2) thinner nonnecrotic intima, (3) fewer smooth-muscle cells present at lower densities, (4) less extensive foam cell infiltration in non-atherosclerosis-related cause-of-death cases, and (5) a prominent association of foam cell infiltration with atherosclerosis-related causes of death, which was lacking in the aorta. It is suggested that the lower threshold for atheronecrosis in the coronaries compared with the aorta might be related to the relative deficiency of smooth-muscle cells and foam cells.