Distribution of fatty and fibrous plaques in young human coronary arteries

We have correlated atheromatous plaque distribution with vessel geometry in coronary arteries from subjects dying of non-cardiovascular causes under 40 years of age. After standardised preparation, the area, and circumferential and longitudinal position of each plaque, were measured in the major coronary arteries. Of 41 sets of vessels, two were free of disease. In the remainder, total plaque area varied from 8 to 586 mm2. Half the cases showed fatty plaques only, and half showed both fatty and fibrous plaques. We analysed the distribution of plaques in those vessels affected only by very early fatty disease. In all vessels, plaques were concentrated proximally, but in the left anterior descending and circumflex branches the wall close to the flow-divider was spared. Circumferential distribution was also not random. In the right coronary artery, lesions were concentrated on the inner wall of the major curvature. In the left anterior descending branch, lesions spiralled anticlockwise from the orifice. We suggest that local mechanical factors may determine these patterns.