how do lipid-rich and calcified plaque differ

The short version: lipid-rich plaques are soft and rupture-prone; calcified plaques can be either dangerous (microcalcifications) or stable (large sheets), depending on the size and pattern of the calcium.

The evidence here comes from a narrative review [2] and a cell-biology review [3], not from a manufacturer-funded trial, so the usual conflicts are absent. But neither study is a clinical trial comparing outcomes in people with one plaque type versus the other. The review [2] states that microcalcifications mark vulnerable plaques that can cause heart attacks, while large dense calcifications mark stable plaques. The cell work [3] shows that vascular smooth muscle cells can turn into bone-like cells and drive calcification, which explains the mechanism.

The key distinction is size and pattern, not just presence of calcium. A coronary calcium score (CAC) from a CT scan measures total calcium but cannot tell micro from macro. That matters because a high CAC score can mean either stable old plaque or a mix that includes dangerous microcalcifications. The review [2] also reports that statin therapy slows plaque growth but increases calcium burden progression, while reducing new high-risk features — a trade-off the establishment rarely mentions.

My call: the evidence supports the hypothesis that lipid-rich and calcified plaques differ in stability, but the critical variable is calcium size, not just presence. Confidence: moderate — the mechanistic evidence is solid, but the clinical studies that directly compare outcomes by plaque type in unconfounded populations are thin.