Medial thickenings of coronary artery and the aging risk factor for atherosclerosis.

The objective here is to inquire what kind of coronary artery is it that tends to acquire atheroma: When an atheroma is found somewhere in the specimen (YesA specimen), what do we see in the specimen far away from the atheroma? Previous studies found thicker intima in YesA specimens than in NoA specimens, but with equal numbers of smooth muscle cells (SMC's). Thickness per SMC strongly predicted atheroma, so much so that the risk factor age was fully explained statistically. This study now finds that the medial layer is also thicker in YesA specimens, and with medial SMC numbers equal to those in NoA specimens. Hence, the aging risk factor appears to induce excessive thickness per SMC as a generalized property throughout the whole specimen in the medial as well as intimal layers, with excessive production of collagenous matrix acting as an initial, rate limiting step in plaque formation. In the intima, atheroma tends to occur when average thickness per SMC exceeds the threshold value of 8.6 microm/SMC. The extreme high value found in the most severely affected medial sample was 4.2 microm/SMC, and this failure to approach the threshold could explain the medial resistance to fatty degenerations.