Sudden death and coronary intimal thickening

Among 22 fetuses dying suddenly and unexpectedly after 35 weeks of gestation, in 12 (55%) cases, multifocal structural alterations of all the coronary arteries were reported, and these were more severe along the anterior descending branch of the left coronary artery. In seven (32%) of these fetuses, foci of altered architecture of the media with thinning and fiber fragmentation were observed, even in fields far from the bifurcations. The smooth muscle cells (SMCs) showed loss of polarity, forming columns of myocytes located perpendicular to the axis of the media itself and infiltrating the subendothelial connective tissue. In five (23%) additional fetuses, besides this intense reaction of the SMCs of the media, increased amounts of mucoid ground substance were observed in the subendothelial connective tissue, with formation of intimal lesions of proliferative aspect. Such processes also seem to determine fragmentation and detachment of the internal elastic membrane.