Vulnerability of the thin cap fibroatheroma. The vulnerable plaque: Currently the vulnerable plaque has been defined as containing the following: 1. Large lipid core. 2. Thin fibrous cap. 3. Inflammatory changes at the shoulder of the fibrous cap. 4. Decreased smooth muscle cells within the fibrous cap. This "Hot" – vulnerable thin-cap fibrous atheromatous plaque is associated with angiogenesis, inflammation, being lipid laden and acidic, and fibrotic. The endothelium is activated and these plaques are prone to rupture resulting in acute coronary syndromes.