Angiotensin converting enzyme inhibitors improve endothelial function in patients with coronary artery disease. These effects are more pronounced than the structural changes seen on angiography. Calcium antagonists have been shown experimentally to improve impaired endothelial function, e.g. in hypercholesterolaemia. Antioxidants such as probucol and vitamin C improve endothelium-dependent vasodilation in patients with hyperlipidaemia or diabetes and in smokers. Plaque fissuring is increasingly regarded as the result of chronic inflammatory changes in the shoulder region of the fibrous cap.
Recent work demonstrates that inflammation leads to decreased stability of the atheromatous plaque.
Inflammatory mediators such as cytokines influence several biological processes in the plaque's fibrous cap lessening its resistance to rupture. For example, interferon-g, produced by activated T cells in the cap, inhibits the production of interstitial collagen by human vascular smooth muscle cells. Regions of the plaque that are prone to rupture contain few smooth muscle cells, the cells that normally elaborate and repair the vascular matrix. Thus, inflammatory mediators regulate several molecular processes that impair the stability of the plaque. 2.8.3.2 Oxidized LDL Lipoproteins undergo minimal oxidation in the circulation but become progressively oxidized within the arterial wall.