Composition of atherosclerotic plaques in the four major epicardial coronary arteries in patients greater than or equal to 90 years of age.

The composition of atherosclerotic plaques in 733 five-mm segments of the 4 major (left main, left anterior descending, left circumflex and right) epicardial coronary arteries of 18 patients greater than or equal to 90 years of age was determined by computerized planimetric analysis. By analysis of all coronary segments of all patients greater than 90, the plaques consisted primarily of fibrous tissue (87 +/- 8%) with calcific deposits (7 +/- 6%), pultaceous debris (5 +/- 4%) and foam cells (1 +/- 1%) occupying a much smaller percentage of plaque area. Analysis of composition according to the 4 degrees of luminal cross-sectional area narrowing revealed marked step-wise increases in pultaceous debris (from 0 +/- 0% at 0 to 25% narrowing to 18 +/- 22% at 76 to 100% narrowing, p = 0.0001) and calcific deposits (from 0 +/- 0 to 10 +/- 15%, p = 0.002), and decreases in fibrous tissue (from 99 +/- 3 to 71 +/- 23%, p = 0.0001) and area occupied by the media (from 35 +/- 8 to 16 +/- 8%, p = 0.0001). When the analysis was restricted to sections narrowed greater than 75%, no significant differences were found in plaque components or medial area between patients with (11 patients) and without (7 patients) myocardial infarcts at necropsy.