Calcification in atherosclerosis

Coronary calcification has long been known to occur as a part of the atherosclerotic process, although whether it is a marker of plaque stability or instability is still a topic of considerable debate. Coronary calcification is an active process resembling bone formation within the vessel wall and, with the advances in CT technology of the past decade, can be easily quantified and expressed as a coronary artery calcium (CAC) score. The extent of calcium is thought to reflect the total coronary atherosclerotic burden, which has generated interest in using CAC as a marker of risk of cardiovascular events. The current consensus is that large amounts of CAC identify a highly vulnerable patient rather than a vulnerable plaque or vulnerable vessel. Indeed, CAC has incremental prognostic value beyond traditional risk factors in various subsets of the population. Furthermore, whereas the presence of CAC is associated with increased risk, a zero CAC score predicts excellent short-term to mid-term prognosis, even in high-risk patients. The advent of CT angiography has perhaps clouded the importance of CAC as a long-term marker of risk, as opposed to the presence of luminal stenoses that are associated with a more immediate risk of events.